The development of astronomy in ancient Greece. Universe exploration

In antiquity, astronomy was the most developed among all other sciences. One reason for this was that astronomical phenomena are easier to understand than phenomena observed on the surface of the Earth. Although the ancients did not know this, then, as now, the Earth and other planets moved around the Sun in orbits close to circular, at approximately constant speed, under the influence of the only force - gravity, and also rotated around their axes, in general, with constant speeds. All this is true for the motion of the Moon around the Earth. As a result, the Sun, Moon, and planets appear from the Earth to move in an orderly and predictable manner, and their motion can be studied with sufficient accuracy.

Another reason was that in ancient times astronomy was of practical importance, unlike physics. How astronomical knowledge was used, we will see in chapter 6.

In Chapter 7, we will look at what was, despite the inaccuracies, the triumph of science in the Hellenistic era: the successful measurement of the sizes of the Sun, Moon, and Earth, as well as the distances from the Earth to the Sun and Moon. Chapter 8 is devoted to the problems of analysis and prediction visible movement planets - a problem that remained unresolved by astronomers in the Middle Ages and the solution of which ultimately gave rise to modern science.

6. Practical benefits of astronomy

Even in prehistoric times, people must have navigated the sky like a compass, a clock, and a calendar. It is hard not to notice that the sun rises every morning in approximately the same direction of the world; that one can determine how soon night will fall by looking at how high the sun is above the horizon, and that warm weather occurs at the time of the year when the days are longer.

It is known that stars began to be used for such purposes quite early. About III millennium BC. e. The ancient Egyptians knew that the flood of the Nile, a major event for agriculture, coincided with the day of the heliacal rising of the star Sirius. This is the day of the year when Sirius first becomes visible in the rays of dawn before sunrise; on previous days it is not visible at all, and on subsequent days it appears in the sky earlier and earlier, long before dawn. In the VI century. BC e. Homer in his poem compares Achilles with Sirius, who is seen high in the sky at the end of summer:

Like a star that rises with fiery rays in autumn

And, between countless stars, burning in the dusk of the night

(The dog of Orion is called her sons of men),

It shines brighter than all, but it can be a formidable sign;

She inflicts evil flames on unfortunate mortals ...

Later, the poet Hesiod in the poem "Works and Days" advised farmers to harvest grapes during the days of the heliacal rising of Arcturus; it was necessary to plow in the days of the so-called cosmic setting of the Pleiades star cluster. This is the name of the day of the year when this cluster first sets below the horizon in the last minutes before sunrise; before that, the sun has already risen when the Pleiades are still high in the sky, and after that day they set before the sun rises. After Hesiod, calendars called "parapegma", which gave each day the moments of rising and setting of well-marked stars, became widespread in the ancient Greek city-states, which had no other generally accepted way to mark days.

Observing the starry sky on dark nights, not illuminated by the lights of modern cities, the inhabitants of ancient civilizations clearly saw that, with a number of exceptions, which we will discuss later, the stars do not change their relative position. Therefore, the constellations do not change from night to night and from year to year. But at the same time, the entire set of these “fixed” stars rotates every night from east to west around a special point in the sky, pointing exactly to the north, which was called the north pole of the world. In terms of our day, this is the point where the axis of rotation of the Earth is directed, if it is extended from the north pole of the Earth into the sky.

These observations made the stars useful from ancient times for sailors, who used them to determine the location of the cardinal points at night. Homer describes how Odysseus, on his way home to Ithaca, was captured by the nymph Calypso on her island in the western Mediterranean and remained captive until Zeus ordered her to release the traveler. Parting words to Odysseus, Calypso advises him to navigate by the stars:

Turning the rudder, he was awake; sleep did not descend on him

Eyes, and did not take them […] from the Bear, there are still Chariots in people

The name of the bearer and near Orion doing forever

Circle your own, never bathing yourself in the waters of the ocean.

With her, the goddess of goddesses commanded him vigilantly

The path to agree with her, leaving her on the left hand.

Ursa is, of course, the constellation Ursa Major, also known to the ancient Greeks as the Chariot. It is located near the north pole of the world. For this reason, at the latitudes of the Mediterranean, the Big Dipper never sets ("... never bathing itself in the waters of the ocean," as Homer put it) and is always visible at night in a more or less northerly direction. Keeping the Bear on the port side, Odysseus could constantly maintain a course east, to Ithaca.

Some ancient Greek observers realized that among the constellations there are more convenient landmarks. The biography of Alexander the Great by Lucius Flavius ​​Arrian mentions that although most navigators preferred to determine north by Big Dipper, Phoenicians, real sea wolves ancient world, for this purpose they used the constellation Ursa Minor - not as bright as Ursa Major, but closer in the sky to the pole of the world. The poet Callimachus from Cyrene, whose words are quoted by Diogenes Laertes, stated that Thales invented the way to search for the pole of the world along Ursa Minor.

The sun also makes a visible path across the sky from east to west during the day, moving around the north celestial pole. Of course, during the day the stars are usually not visible, but apparently Heraclitus, perhaps his predecessors, understood that their light was lost in the radiance of the sun. Some stars can be seen shortly before dawn or shortly after sunset, when its position on the celestial sphere is obvious. The position of these stars changes during the year, and from this it is clear that the Sun is not at the same point in relation to the stars. More precisely, as was well known in ancient Babylon and India, in addition to the apparent daily rotation from east to west along with all the stars, the Sun also rotates annually in the opposite direction, from west to east, along the path known as the zodiac, which contains the traditional zodiac constellations: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces. As we shall see, the Moon and planets also move through these constellations, although not on the same paths. The path that the Sun makes through them is called ecliptic .

Having understood what the zodiac constellations are, it is easy to determine where the Sun is now among the stars. You just need to see which of the constellations of the zodiac is visible above all in the sky at midnight; The sun will be in the constellation opposite this one. It is claimed that Thales calculated that one complete revolution of the Sun in the zodiac takes 365 days.

An observer from the Earth may believe that the stars are located on a solid sphere surrounding the Earth, the celestial pole of which is located above the north pole of the Earth. But the zodiac does not coincide with the equator of this sphere. Anaximander is credited with the discovery that the zodiac is located at an angle of 23.5 ° with respect to the celestial equator, with the constellations Cancer and Gemini being closest to the north celestial pole, and Capricorn and Sagittarius the farthest from it. We now know that this tilt, which causes the change of seasons, exists because the axis of rotation of the Earth is not perpendicular to the plane of the Earth's orbit around the Sun, which, in turn, coincides quite accurately with the plane in which almost all bodies move. solar system. The deviation of the earth's axis from the perpendicular is an angle of 23.5 °. When it is summer in the Northern Hemisphere, the sun is in the direction where the Earth's north pole is tilted, and when it is winter, it is in the opposite direction.

Astronomy as an exact science began with the use of a device known as the gnomon, which made it possible to measure the apparent movement of the sun across the sky. Bishop Eusebius of Caesarea in the 4th century. wrote that Anaximander invented the gnomon, but Herodotus attributed the merit of its creation to the Babylonians. This is just a rod, vertically mounted on a flat area illuminated by the sun. With the help of the gnomon, you can say exactly when noon comes - at this moment the sun is highest in the sky, so the gnomon casts the shortest shadow. In any place on earth north of the tropics at noon, the sun is located exactly in the south, which means that the shadow from the gnomon points at that moment exactly to the north. Knowing this, it is easy to mark the site according to the shadow of the gnomon, putting directions on it to all cardinal points, and it will serve as a compass. Also, the gnomon can work as a calendar. In spring and summer, the sun rises slightly north of the east point on the horizon, and in autumn and winter - south of it. When the shadow of the gnomon at dawn points exactly to the west, the sun rises exactly in the east, which means that today is the day of one of the two equinoxes: either spring, when winter gives way to spring, or autumn, when summer ends and autumn comes. On the day of the summer solstice, the shadow of the gnomon at noon is the shortest, on the day of the winter, respectively, the longest. A sundial is similar to a gnomon, but arranged differently - their rod is parallel to the Earth's axis, and not a vertical line, and the shadow from the rod every day, at the same time, points in the same direction. Therefore, a sundial is, in fact, a clock, but it cannot be used as a calendar.

The gnomon is a perfect example of the important connection between science and technology: a technical contraption invented with practical purpose, which makes it possible to scientific discoveries. With the help of the gnomon, an accurate calculation of the days in each of the seasons became available - the period of time from one equinox to the solstice and then to the next equinox. Thus, Euctemon, a contemporary of Socrates who lived in Athens, discovered that the lengths of the seasons do not coincide exactly. This turned out to be unexpected if we consider that the Sun moves around the Earth (or the Earth around the Sun) in a regular circle with the Earth (or the Sun) in the center at a constant speed. Based on this assumption, all seasons must be exactly the same length. For centuries, astronomers tried to understand the reason for their actual inequality, but the correct explanation of this and other anomalies did not appear until the 17th century, when Johannes Kepler realized that the Earth revolves around the Sun in an orbit that is not a circle, but an ellipse, and the Sun is not located in its center, but shifted to a point called the focus. In this case, the movement of the Earth either accelerates or slows down as it approaches or moves away from the Sun.

For an earthly observer, the moon also rotates together with the starry sky every night from east to west around the north pole of the world and, just like the Sun, slowly moves along the zodiac circle from west to east, but its complete revolution in relation to the stars, “against the background” which it occurs, takes a little more than 27 days, not a year. Since for the observer the Sun moves along the zodiac in the same direction as the Moon, but more slowly, about 29.5 days pass between the moments when the Moon is in the same position with respect to the Sun (actually 29 days 12 hours 44 minutes and 3 seconds). Since the phases of the moon depend on the relative position of the sun and moon, it is this interval of 29.5 days that is the lunar month, that is, the time passing from one new moon to another. It has long been observed that lunar eclipses occur in the phase of the full moon and their cycle repeats every 18 years, when the apparent path of the Moon against the background of the stars intersects with the path of the Sun.

In some respects, the Moon is more calendar-friendly than the Sun. By observing the phase of the moon on any night, you can roughly tell how many days have passed since the last new moon, and this is a much more accurate way than trying to determine the time of year just by looking at the sun. Therefore, lunar calendars were very common in the ancient world and are still used today - for example, such is the Islamic religious calendar. But, of course, in order to make plans in agriculture, navigation or military affairs, one must be able to predict the change of seasons, and it occurs under the influence of the Sun. Unfortunately, there is not an integer number of lunar months in a year - a year is about 11 days longer than 12 full lunar months, and for this reason the date of any solstice or equinox cannot remain the same in a calendar based on the changing phases of the moon.

Another well-known difficulty is that the year itself does not take an integer number of days. In the time of Julius Caesar, it was customary to consider every fourth year a leap year. But this did not completely solve the problem, since the year does not last exactly 365 days and a quarter, but 11 minutes longer.

History remembers countless attempts to create a calendar that would take into account all these difficulties - there were so many of them that it makes no sense to talk about all of them here. A fundamental contribution to the solution of this issue was made in 432 BC. e. the Athenian Meton, who may have been a colleague of Euctaemon. Using probably the Babylonian astronomical chronicles, Meton determined that 19 years correspond exactly to 235 lunar months. The error is only 2 hours. Therefore, it is possible to create a calendar, but not for one year, but for 19 years, in which both the season and the phase of the moon will be exactly defined for each day. The days of the calendar will repeat every 19 years. But since 19 years is almost exactly equal to 235 lunar months, this interval is one third of a day shorter than exactly 6940 days, and for this reason Meton prescribed every few 19-year cycles to drop one day from the calendar.

The efforts of astronomers to harmonize the solar and lunar calendars are well illustrated by the definition of the day of Easter. The Council of Nicaea in 325 declared that Easter should be celebrated every year on the Sunday after the first full moon following the spring equinox. During the reign of Emperor Theodosius I the Great, it was established by law that the celebration of Easter on the wrong day was strictly punished. Unfortunately, the exact date of the vernal equinox is not always the same in different parts of the earth. To avoid the dire consequences of someone somewhere celebrating Easter on the wrong day, it became necessary to designate one of the days as the exact day of the vernal equinox, as well as agree on exactly when the next full moon occurs. The Roman Catholic Church in the late antique period began to use the Metonic cycle for this, while the monastic orders of Ireland adopted the earlier Jewish 84-year cycle as a basis. flared up in the 17th century. the struggle between the missionaries of Rome and the monks of Ireland for control of the English church was mainly provoked by a dispute over the exact date of Easter.

Before the advent of the New Age, the creation of calendars was one of the main activities of astronomers. As a result, in 1582, the calendar generally accepted today was created and, under the patronage of Pope Gregory XIII, was put into use. To determine the day of Easter, it is now considered that the vernal equinox always occurs on March 21, but only on March 21 according to the Gregorian calendar in the Western world and the same day, but according to the Julian calendar, in countries professing Orthodoxy. As a result, different parts of the world celebrate Easter on different days.

Although astronomy was already a useful science in the Classical era of Hellas, Plato was not impressed by this. In the dialogue "The State" there is a place illustrating his point of view in a conversation between Socrates and his opponent Glaucon. Socrates argues that astronomy should be a compulsory subject to be taught to future philosopher kings. Glavkon easily agrees with him: “In my opinion, yes, because careful observations of the change of seasons, months and years are suitable not only for agriculture and navigation, but no less for directing military operations.” However, Socrates declares this view naive. For him, the meaning of astronomy lies in the fact that “... in these sciences, a certain instrument of the soul of every person is cleansed and revived again, which other occupations destroy and make blind, but meanwhile keeping it intact is more valuable than having a thousand eyes, because only with with his help one can see the truth.” Such intellectual arrogance was less characteristic of the Alexandrian school than of the Athenian, but even in the works of, for example, the philosopher Philo of Alexandria in the 1st century. it is noted that "perceived by the mind is always higher than all that is perceived and seen by the senses." Fortunately, even if under the pressure of practical necessity, astronomers gradually weaned themselves from relying on their own intelligence alone.

Astronomy of Ancient Greece- astronomical knowledge and the views of those people who wrote in ancient Greek, regardless of the geographical region: Hellas itself, the Hellenized monarchies of the East, Rome or early Byzantium. Ancient Greek astronomy is one of the most important stages in the development of not only astronomy as such, but also science in general. In the works of ancient Greek scientists are the origins of many ideas that underlie the science of modern times. There is a relationship of continuity between modern and ancient Greek astronomy, while the science of other ancient civilizations influenced modern only through the mediation of the Greeks.

Scientific Method of Ancient Greek Astronomy

The main achievement of the astronomy of the ancient Greeks should be considered the geometrization of the Universe, which includes not only the systematic use of geometric structures to represent celestial phenomena, but also a rigorous logical proof of statements along the lines of Euclidean geometry.

The dominant methodology in ancient astronomy was the ideology of "saving phenomena": it is necessary to find such a combination of uniform circular motions, with the help of which any unevenness of the visible movement of the luminaries can be modeled. The "rescue of phenomena" was conceived by the Greeks as a purely mathematical problem, and it was not assumed that the combination of uniform circular motions found had any relation to physical reality. The task of physics was considered to be the search for an answer to the question "Why?", that is, the establishment of the true nature of celestial objects and the causes of their movements based on the consideration of their substance and the forces acting in the Universe; the use of mathematics was not considered necessary.

periodization

The history of ancient Greek astronomy can be divided into four periods associated with various stages in the development of ancient society:

• Pre-scientific period (until the 6th century BC): the formation of the polis structure in Hellas;
• Classical period (VI-IV centuries BC): dawn of the ancient Greek policy;
• Hellenistic period (III-II century BC): the rise of large monarchical powers that arose on the ruins of the empire of Alexander the Great; from the point of view of science, Ptolemaic Egypt, with its capital in Alexandria, plays a special role;
• The period of decline (I century BC - I century AD), associated with the gradual extinction of the Hellenistic powers and the strengthening of the influence of Rome;
• Imperial period (2nd-5th centuries CE): the unification of the entire Mediterranean, including Greece and Egypt, under the rule of the Roman Empire.

This periodization is rather schematic. In some cases, it is difficult to establish the affiliation of a particular achievement to a particular period. So, although the general character of astronomy and science in general in the classical and Hellenistic periods looks quite different, on the whole, development in the 6th-2nd centuries BC. e. appears to be more or less continuous. On the other hand, a number of scientific achievements of the last, imperial period (especially in the field of astronomical instrumentation and, possibly, theory) are nothing more than a repetition of the successes achieved by astronomers of the Hellenistic era.

Pre-scientific period (until the 6th century BC)

The poems of Homer and Hesiod give an idea of ​​the astronomical knowledge of the Greeks of this period: a number of stars and constellations are mentioned there, practical advice is given on the use of celestial bodies for navigation and for determining the seasons of the year. The cosmological ideas of this period were entirely borrowed from myths: the Earth is considered flat, and the sky is a solid bowl resting on the Earth.

At the same time, according to the opinion of some historians of science, the members of one of the Hellenic religious and philosophical unions of that time (the Orphics) also knew some special astronomical concepts (for example, ideas about some celestial circles). However, most researchers do not agree with this opinion.

Classical period (from VI - to IV century BC)

Main actors of this period are philosophers who intuitively grope for what will later be called the scientific method of cognition. At the same time, the first specialized astronomical observations are being made, the theory and practice of the calendar is being developed; for the first time, geometry is taken as the basis of astronomy, a number of abstract concepts of mathematical astronomy are introduced; attempts are being made to find physical patterns in the movement of the luminaries. Received scientific explanation row astronomical phenomena, proved the sphericity of the Earth. At the same time, the connection between astronomical observations and theory is still not strong enough; there is too much speculation based on purely aesthetic considerations.

Sources

Only two specialized astronomical works of this period have come down to us, treatises About the rotating sphere And About the rising and setting of the stars Autolycus of Pitana - textbooks on spherical astronomy, written at the very end of this period, around 310 BC. e. They are also accompanied by a poem phenomena Arata from Sol (written, however, in the first half of the 3rd century BC), which contains a description of the ancient Greek constellations (a poetic transcription of the works of Eudoxus of Cnidus (4th century BC) that have not come down to us).

Questions of an astronomical nature are often touched upon in the writings of ancient Greek philosophers: some of Plato's dialogues (especially Timaeus, as well as State, Phaedo, Laws, Afterlaw), treatises of Aristotle (especially About Heaven, as well as meteorology, Physics, Metaphysics). The works of philosophers of an earlier time (pre-Socratics) have come down to us only in a very fragmentary form through second, and even third hands.

Philosophical Foundation of Astronomy

During this period, two fundamentally different philosophical approaches were developed in science in general and astronomy in particular. The first of them originated in Ionia and therefore can be called Ionian. It is characterized by attempts to find the material fundamental principle of being, by changing which philosophers hoped to explain all the diversity of nature. In move celestial bodies these philosophers tried to see manifestations of the same forces that operate on Earth. Initially, the Ionian direction was represented by the philosophers of the city of Miletus Thales, Anaximander and Anaximenes. This approach found its supporters in other parts of Hellas. Among the Ionians is Anaxagoras of Klazomen, who spent a significant part of his life in Athens, to a large extent a native of Sicily, Empedocles of Acragas. The Ionian approach reached its peak in the writings of the ancient atomists: Leucippus (probably also from Miletus) and Democritus from Abdera, who were the forerunners of mechanistic philosophy.

The desire to give a causal explanation of natural phenomena was the strength of the Ionians. In the present state of the world, they saw the result of evolution under the influence of physical strength without involvement mythical gods and monsters. They were the first to be called physicists. However, the shortcoming of the teachings of the Ionian natural philosophers was an attempt to create physics without mathematics. The Ionians did not see the geometric basis of the Cosmos.

The second direction of early Greek philosophy can be called Italian, since it received its initial development in the Greek colonies of the Italian peninsula. Its founder Pythagoras founded the famous religious and philosophical union, whose representatives, unlike the Ionians, saw the basis of the world in mathematical harmony, more precisely, in the harmony of numbers, while striving for the unity of science and religion. They considered the heavenly bodies to be gods. This was justified as follows: the gods are a perfect mind, they are characterized by the most perfect type of movement; this is the circumferential motion, because it is eternal, has no beginning and no end, and always passes into itself. As astronomical observations show, celestial bodies move in circles, therefore, they are gods. The heir of the Pythagoreans was the great Athenian philosopher Plato, who believed that the entire Cosmos was created by an ideal deity in his own image and likeness. Although the Pythagoreans and Plato believed in the divinity of the heavenly bodies, they were not characterized by faith in astrology: an extremely skeptical review of it by Eudoxus, a student of Plato and a follower of the philosophy of the Pythagoreans, is known.

The desire to search for mathematical patterns in nature was the strength of the Italians. The Italian passion for ideal geometric shapes allowed them to be the first to suggest that the Earth and celestial bodies are spherical and open the way to the application of mathematical methods to the knowledge of nature. However, believing the celestial bodies to be deities, they almost completely expelled physical forces from heaven.

File:Stagirit world colour.gif

The structure of the universe according to Aristotle. The spheres are marked by numbers: earth (1), water (2), air (3), fire (4), ether (5), prime mover (6). The scale is not respected

The strengths of these two research programs, Ionian and Pythagorean, complemented each other. An attempt to synthesize them was made by Aristotle from Stagira. The most important principle of the school he founded, the Lyceum, was the observation of nature. To a large extent, we owe to Aristotle the most important requirement for a scientific theory: the theory must be logical, consistent with itself, and at the same time it must correspond to observational data. However, the Aristotelian synthesis of Ionian and Italic was largely unsuccessful. Aristotle, as it were, cut the universe vertically. Top part, the supralunar world, as a whole corresponded to the Pythagorean-Platonic ideal of perfect harmony. Although Aristotle did not call the heavenly bodies gods, he considered them to be of a divine nature, being composed of perfect matter - ether, which is characterized by the most perfect type of movement - eternal unchanging movement in a circle. The theory of the sublunar world, on the contrary, resembles the constructions of the Ionian philosophers (of the pre-atomistic period) with their refusal to apply mathematics to the search for natural patterns. The sublunar world was characterized by movement along vertical straight lines; such a movement must have a beginning and an end, which corresponds to the frailty of everything earthly.

Practical astronomy

Only fragmentary information about the methods and results of observations by astronomers of the classical period has come down to us. Based on the available sources, it can be assumed that one of the main objects of their attention was the rising of the stars, since the results of such observations could be used to determine the time at night. A treatise with data from such observations was compiled by Eudoxus of Cnidus (second half of the 4th century BC); the poet Arat clothed the treatise of Eudoxus in a poetic form.

To calculate the time during the day, apparently, a sundial was often used. First, spherical sundials were invented, as the simplest ones. Improvements in sundial design have also been attributed to Eudoxus. It was probably the invention of one of the varieties of flat sundials.

Ionian philosophers believed that the movement of heavenly bodies was controlled by forces similar to those that operate on an earthly scale. So, Empedocles, Anaxagoras, Democritus believed that celestial bodies do not fall to Earth, since they are held by centrifugal force. The Italians (Pythagoreans and Plato) believed that the luminaries, being gods, move by themselves, like living beings. Aristotle believed that celestial bodies are carried in their motion by solid celestial spheres to which they are attached.

There has been considerable disagreement among philosophers about what is outside the Cosmos. Some philosophers believed that there is an infinite empty space; according to Aristotle, there is nothing outside the Cosmos, not even space; atomists Leucippus, Democritus and their supporters believed that behind our world (limited by the sphere of fixed stars) there are other worlds. The closest to modern were the views of Heraclid Pontus, according to which the fixed stars are other worlds located in infinite space.

Explanation of astronomical phenomena and the nature of celestial bodies

The classical period is characterized by widespread speculation about the nature of celestial bodies. Anaxagoras of Klazomen (5th century BC) was the first to suggest that the Moon shines by the reflected light of the Sun, and on this basis, for the first time in history, he gave a correct explanation of the nature of the lunar phases and solar and lunar eclipses. Anaxagoras considered the sun to be a giant stone (the size of the Peloponnese), red-hot due to friction against the air (for which the philosopher almost suffered death penalty, since this hypothesis was considered contrary to the state religion). Empedocles considered the Sun not an independent object, but a reflection in the firmament of the Earth, consecrated by heavenly fire. The Pythagorean Philolaus believed that the Sun is a transparent spherical body, luminous because it refracts the light of heavenly fire; what we see as daylight is the image produced in the Earth's atmosphere. Some philosophers (Parmenides, Empedocles) believed that the brightness of the daytime sky is due to the fact that the firmament consists of two hemispheres, light and dark, the period of revolution of which around the Earth is a day, like the period of revolution of the Sun.

Comets attracted great attention of Greek scientists. The Pythagoreans considered them to be a kind of planets. These opinions were rejected by Aristotle, who considered comets (like meteors) to be the ignition of the air in the upper part of the sublunar world. The reason for these ignitions lies in the heterogeneity of the air surrounding the Earth, the presence of easily flammable inclusions in it, which flare up due to the transfer of heat from the ether rotating above the sublunar world. According to Aristotle, the Milky Way has the same nature; the only difference is that in the case of comets and meteors, the glow arises from the heating of the air by one particular star, while the Milky Way arises from the heating of the air by the entire supralunar region. Some Pythagoreans, along with Oenopides of Chios, considered the Milky Way to be a scorched trajectory along which the Sun once circulated. Anaxagoras believed the Milky Way to be an apparent cluster of stars, located in the place where the earth's shadow falls on the sky. An absolutely correct point of view was expressed by Democritus, who believed that the Milky Way is a joint glow of many nearby stars.

Mathematical astronomy

The main achievement of mathematical astronomy of the period under review is the concept of the celestial sphere. Probably, initially it was a purely speculative idea based on considerations of aesthetics. However, later it was realized that the phenomena of sunrise and sunset of the luminaries, their climaxes really occur in such a way as if the stars were rigidly fastened to a spherical firmament, rotating around an axis inclined to the earth's surface. Thus, the main features of the movements of stars were naturally explained: each star always rises at the same point on the horizon, different stars pass different arcs across the sky at the same time, and the closer the star to the celestial pole, the smaller the arc it passes in one and the same time. A necessary stage in the work on the creation of this theory should have been the realization that the size of the Earth is immeasurably small compared to the size of the celestial sphere, which made it possible to neglect the daily parallaxes of stars. The names of the people who made this most important intellectual revolution have not come down to us; most likely they belonged to the Pythagorean school. The earliest handbook on spherical astronomy that has come down to us belongs to Autolycus of Pitana (about 310 BC). It was proved there, in particular, that points of a rotating sphere that do not lie on its axis, during uniform rotation, describe parallel circles perpendicular to the axis, and in equal time all points of the surface describe similar arcs.

Another major achievement of the mathematical astronomy of classical Greece is the introduction of the concept of the ecliptic - a large circle inclined with respect to the celestial equator, along which the Sun moves among the stars. This idea was probably introduced by the famous geometer Oenopides of Chios, who also made the first attempt to measure the inclination of the ecliptic to the equator (24°).

The ancient Greek astronomers put the following principle at the basis of the geometric theories of the motion of celestial bodies: the motion of each planet, the Sun and the Moon is a combination of uniform circular motions. This principle, proposed by Plato or even the Pythagoreans, comes from the concept of celestial bodies as deities, which can only have the most perfect type of movement - uniform movement in a circle. It is believed that the first theory of the motion of celestial bodies based on this principle was proposed by Eudoxus of Cnidus. It was the theory of homocentric spheres - a kind of geocentric system of the world, in which celestial bodies are considered rigidly attached to a combination of rigid spheres fastened together with a common center. The improvement of this theory was carried out by Callippus of Cyzicus, and Aristotle put it at the basis of his cosmological system. The theory of homocentric spheres was subsequently abandoned, as it assumes the invariability of the distances from the luminaries to the Earth (each of the luminaries moves along a sphere whose center coincides with the center of the Earth). However, by the end of the classical period, a significant amount of evidence had already been accumulated that the distances of celestial bodies from the Earth actually change: significant changes in the brightness of some planets, the variability of the angular diameter of the Moon, the presence along with total and annular solar eclipses.

File:Eudoxus planets3.PNG

A system of four concentric spheres used to model the motion of the planets in the Eudoxian theory. The numbers indicate the spheres responsible for the daily rotation of the sky (1), for the movement along the ecliptic (2), for the backward movements of the planet (3 and 4). T - Earth, the dotted line represents the ecliptic (the equator of the second sphere).

Hellenistic period (III-II centuries BC)

The most important organizing role in the science of this period is played by the Library of Alexandria and Museion. Although at the beginning of the Hellenistic period, two new philosophical schools, the Stoics and the Epicureans, arose, scientific astronomy had already reached a level that allowed it to develop practically without being influenced by certain philosophical doctrines (it is possible, however, that religious prejudices associated with the philosophy of Stoicism , had a negative impact on the propagation of the heliocentric system: see Cleanf's example below).

Astronomy becomes an exact science. The most important tasks of astronomers are: (1) establishing the scale of the world based on the theorems of geometry and astronomical observations, as well as (2) building predictive geometric theories of the motion of celestial bodies. The technique of astronomical observations reaches a high level. The unification of the ancient world by Alexander the Great makes possible the enrichment of Greek astronomy due to the achievements of the Babylonian astronomers. At the same time, the gap between astronomy and physics, which was not so obvious in the previous period, deepens, and by its end, astrology, which came from Babylon, is widely spread in the Hellenistic world.

Sources

Six works of astronomers of this period have come down to us:

The achievements of this period formed the basis of two elementary astronomy textbooks Gemina (1st century BC) and Cleomedes (lifetime unknown, most likely between the 1st century BC and the 2nd century AD), known as Introduction to Phenomena. Claudius Ptolemy tells about the works of Hipparchus in his fundamental work - Almagest (2nd half of the 2nd century AD). In addition, various aspects of astronomy and cosmology of the Hellenistic period are covered in a number of commentary works of later periods.

Practical astronomy

ancient greek sundial

In order to improve the calendar, scientists of the Hellenistic era made observations of the solstices and equinoxes: the length of the tropical year is equal to the time interval between two solstices or equinoxes, divided by the total number of years. They understood that the accuracy of the calculation is higher, the greater the interval between the events used. Such observations were made, in particular, by Aristarchus of Samos, Archimedes of Syracuse, Hipparchus of Nicaea and a number of other astronomers whose names are unknown.

Work on determining star coordinates continued in the second half of the II century BC. e. Hipparchus, who compiled the first star catalog in Europe, which included the exact coordinates of about a thousand stars. This catalog has not come down to us, but it is possible that the catalog from the Ptolemaic Almagest is almost entirely the catalog of Hipparchus with coordinates recalculated due to precession. When compiling his catalog, Hipparchus first introduced the concept of stellar magnitudes.

In the second half of the III century BC. e. Alexandrian astronomers also made observations of the positions of the planets. Among them were Timocharis and astronomers whose names we do not know (all we know about them is that they used Dionysius' zodiac calendar to date their observations). The motives behind the Alexandrian observations are not entirely clear.

In order to determine the geographical latitude in various cities, observations were made of the height of the Sun during the solstices. In this case, an accuracy of the order of several arc minutes was achieved, the maximum achievable naked eye.To determine the longitude, observations of lunar eclipses were used (the difference in longitude between two points is equal to the difference in local time when the eclipse occurred).

equatorial ring.

What tools were used in the course of these works is not known with certainty. Probably, a diopter was used to observe the night luminaries, and a midday circle was used to observe the Sun; the use of an astrolabe and an armillary sphere is also highly likely. According to Ptolemy, Hipparchus used the equatorial ring to determine the moments of the equinoxes.

Most historians of science believe that the heliocentric hypothesis did not receive any significant support from Aristarchus' contemporaries and later astronomers. Some researchers, however, provide a number of indirect evidence of the widespread support for heliocentrism by ancient astronomers. However, the name of only one supporter of the heliocentric system is known: the Babylonian Seleucus, 1st half of the 2nd century BC. e.

There is reason to believe that other astronomers also made estimates of the distances to celestial bodies based on the unobservability of their daily parallaxes; one should also recall the conclusion of Aristarchus about the enormous remoteness of the stars, made on the basis of the heliocentric system and the unobservability of the annual parallaxes of stars.

Apollonius of Perga and Archimedes were also involved in determining the distances to heavenly bodies, but nothing is known about the methods they used. One recent attempt at reconstructing Archimedes' work concluded that his distance to the Moon was about 62 Earth radii and fairly accurately measured the relative distances from the Sun to the planets Mercury, Venus, and Mars (based on a model in which these planets revolve around Sun and with it - around the Earth).

To this must be added the determination of the radius of the Earth by Eratosthenes. To this end, he measured the zenithal distance of the Sun at noon on the day of the summer solstice in Alexandria, obtaining a result of 1/50 of a full circle. Further, Eratosthenes knew that in the city of Siena on this day the Sun is exactly at its zenith, that is, Siena is on the tropic. Assuming these cities to lie exactly on the same meridian and taking the distance between them equal to 5000 stadia, and also considering the rays of the Sun to be parallel, Eratosthenes received the circumference of the earth equal to 250,000 stadia. Subsequently, Eratosthenes increased this value to a value of 252,000 stadia, more convenient for practical calculations. The accuracy of Eratosthenes' result is difficult to assess, since the magnitude of the stad he used is unknown. Most contemporary works stages of Eratosthenes is taken equal to 157.5 meters or 185 meters. Then its result for the circumference of the earth, in terms of our units of measurement, will be equal to, respectively, 39690 km (only 0.7% less than the true value), or 46620 km (17% more than the true value).

Theories of motion of celestial bodies

File:Deferent.gif

Epicycle and deferent

During the period under review, new geometric theories of the motion of the Sun, Moon and planets were created, which were based on the principle that the motion of all celestial bodies is a combination of uniform circular motions. However, this principle acted not in the form of the theory of homocentric spheres, as in the science of the previous period, but in the form of the theory of epicycles, according to which the luminary itself makes a uniform movement in a small circle (epicycle), the center of which moves uniformly around the Earth in a large circle (deferent). The foundations of this theory are believed to have been laid by Apollonius of Perga, who lived at the end of the 3rd - beginning of the 2nd century BC. e.

File:Hipparchus excentre.gif

The motion of the Sun in the theory of Hipparchus. O - center of the Sun's orbit, T - Earth

A number of theories of the motion of the Sun and Moon were built by Hipparchus. According to his theory of the Sun, the periods of movement along the epicycle and the deferent are the same and equal to one year, their directions are opposite, as a result of which the Sun uniformly describes a circle (eccenter) in space, the center of which does not coincide with the center of the Earth. This made it possible to explain the non-uniformity of the apparent motion of the Sun along the ecliptic. The parameters of the theory (the ratio of the distances between the centers of the Earth and the eccentric, the direction of the line of apsides) were determined from observations. A similar theory was created for the Moon, however, on the assumption that the velocities of the Moon along the deferent and the epicycle do not match. These theories enabled eclipse predictions to be made with an accuracy not available to earlier astronomers.

Other astronomers were engaged in the creation of theories of the motion of the planets. The difficulty was that there were two types of unevenness in the motion of the planets:

• inequality relative to the Sun: for the outer planets - the presence of backward movements, when the planet is observed near opposition to the Sun; for the inner planets - backward movements and "attachment" of these planets to the Sun;
• zodiacal inequality: the dependence of the size of the arcs of backward movements and the distances between the arcs on the sign of the zodiac.

To explain these inequalities, Hellenistic astronomers used a combination of movements in eccentric circles and epicycles. These attempts were criticized by Hipparchus, who, however, did not offer any alternative, limiting himself to systematizing the observational data available at his time.

Period of decline (1st century BC - 1st century AD)

During this period, activity in the field of astronomical science is close to zero, but astrology is in full bloom. As evidenced by the numerous papyri of Hellenistic Egypt of that period, horoscopes were drawn up not on the basis of the geometric theories developed by the Greek astronomers of the previous period, but on the basis of the much more primitive arithmetic schemes of the Babylonian astronomers. Philosophers are mainly engaged in developing the foundation of astrology from the standpoint of mysticism.

Nevertheless, some elementary level of astronomical knowledge is preserved, as evidenced by the good astronomy textbook that has come down to us. Introduction to Phenomena Gemina (I century BC). The technology associated with astronomy was also preserved, a clear evidence of which is the mechanism from Antikythera - a calculator of astronomical phenomena, created in the 1st century BC. e.

A noteworthy scholar of this period is the mystical philosopher Posidonius, who was more of an eclecticist and imitator of earlier scholars than an original researcher.

Imperial period (II-V centuries AD)

Astronomy is gradually reviving, but with a noticeable admixture of astrology. During this period, a number of generalizing astronomical works were created. However, the new dawn is rapidly replaced by stagnation and then a new crisis, this time even deeper, associated with the general decline of culture during the collapse of the Roman Empire, as well as with a radical revision of values. ancient civilization produced by early Christianity.

Sources

Astronomy issues are also considered in a number of commentary works written during this period (authors: Theon of Smyrna, II century AD, Simplicius, V century AD, Proclus, V century AD, Censorinus, III century AD e., etc.). Fragmentary information on the history of ancient astronomy is also contained in the works of the encyclopedist Pliny the Elder, the philosophers Cicero, Seneca, Lucretius, Proclus, the architect Vitruvius, the geographer Strabo, and the astrologer Manilius. Some astronomical issues are considered in the works of the mechanic Heron of Alexandria (2nd century AD)

Practical astronomy

The task of planetary observations of the period under consideration is to provide numerical material for the theories of the motion of the planets, the Sun and the Moon. For this purpose, Menelaus, Claudius Ptolemy and other astronomers made their observations (there is a tense discussion on the authenticity of Ptolemy's observations). In the case of the Sun, the main efforts of astronomers were still aimed at accurately fixing the moments of the equinoxes and solstices. In the case of the Moon, eclipses were observed (the exact moment of the largest phase and the position of the Moon among the stars were recorded), as well as quadrature moments. For the inner planets (Mercury and Venus), the greatest elongations were of primary interest when these planets are at the greatest angular distance from the Sun. With the outer planets, special emphasis was placed on fixing the moments of opposition with the Sun and their observation at intermediate times, as well as on studying their backward movements. Astronomers also paid much attention to such rare phenomena as the conjunctions of planets with the Moon, stars, and with each other.

Observations of the coordinates of stars were also made. Ptolemy cites a star catalog in the Almagest, where, according to him, he observed each star independently. It is possible, however, that this catalog is almost entirely the catalog of Hipparchus with the coordinates of stars recalculated due to precession.

Another ancient Roman author, Manilius (1st century AD), cites the opinion that the Sun periodically attracts comets to itself and then makes them move away, like the planets Mercury and Venus. Manilius also testifies that at the beginning of our era, the view was still alive that the Milky Way is a joint glow of many stars located close to each other.

Theories of motion of celestial bodies

Although the theory of the motion of the Sun, Moon and planets has been developed since the Hellenistic period, the first theory that has come down to us is presented in Ptolemy's Almagest. The movement of all celestial bodies is presented as a combination of several movements in large and small circles (epicycles, deferents, eccentres). Ptolemy's solar theory completely coincides with Hipparchus' theory, which we know about only from Almagest. Significant innovations are contained in the lunar theory of Ptolemy, where for the first time a new type of unevenness in the movement of a natural satellite, evection, was taken into account and modeled. The disadvantage of this theory is the exaggeration of the interval of change in the distance from the Earth to the Moon - almost twice, which should be reflected in the change in the angular diameter of the Moon, which is not observed in reality.

The theory of bisection of eccentricity. The points on the circle show the positions of the planet at regular intervals. O - deferent center, T - Earth, E - equant point, A - deferent apogee, P - deferent perigee, S - planet, C - middle planet (center of epicycle)

The most interesting is the planetary theory of Ptolemy (the theory of bisection of eccentricity): each of the planets (except Mercury) moves uniformly in a small circle (epicycle), the center of which moves in a large circle (deferent), and the Earth is displaced relative to the center of the deferent; most importantly, both the angular and linear velocity of the center of the epicycle changes when moving along the deferent, and this movement would look uniform when viewed from a certain point (equant), so that the segment connecting the Earth and the equant is divided by the center of the deferent in half. This theory made it possible to simulate with great accuracy the zodiacal inequality in the motion of the planets.

Whether Ptolemy himself was the author of the theory of the bisection of eccentricity is not known. According to Van der Waerden, which is supported by a number of recent studies, its origins should be sought in the works of scientists of an earlier time that have not come down to us.

The parameters of planetary motion along epicycles and deferents were determined from observations (although it is still unclear whether these observations were falsified). The accuracy of the Ptolemaic model of the motion of Saturn is about 1/2°, Jupiter - about 10" and Mars - more than 1°. In the case of Venus and especially Mercury, the errors can reach several degrees.

Despite the undoubted success of the equant theory in terms of predicting the positions of the planets, most astronomers of a later time (Middle Ages,

The value of ancient Greek astronomy for the development of science

The main merits of ancient Greek astronomy include the following:

• geometrization of the Universe: behind the phenomena observed in the sky, the Greeks saw processes occurring in three-dimensional space;
• consistently logical methodology;
• development of the most important goniometric astronomical instruments;
• introduction of the basic concepts of spherical astronomy and development of spherical trigonometry;
• discovery of the sphericity of the Earth;
• explanation of the nature of a number of important astronomical phenomena;
• discovery of previously unknown phenomena (for example, precession, evection);
• calculation of the distance from the Earth to the Moon;
• the establishment of the smallness of the Earth (and even, among heliocentrists, the smallness of the distance from the Earth to the Sun) in comparison with the distance to the stars;
• Aristarchus of Samos, "On the Sizes and Mutual Distances of the Sun and Moon" Online. The Russian translation is included in the article by I. N. Veselovsky "Aristarchus of Samos - Copernicus of the Ancient World", Historical and Astronomical Research, Vol. VII, 1961 (see pp. 20-46).
• Hesiod, "Works and Days" (contains the oldest references in Greek literature to some constellations). From the collection: Hesiod, Complete collection of texts, M., Labyrinth, 2001. Online
• Gigin, "Astronomy", St. Petersburg, Publishing House Aletheya, 1997. Online
• “The sky, science, poetry. Ancient authors about celestial bodies, about their names, sunrises, sunsets and signs of the weather”, M., Moscow State University, 1997. Online
• S. V. Zhitomirsky, “Antique Astronomy and Orphism”, M., Janus-K, 2001.
• N. I. Idelson, “Etudes on the history of celestial mechanics”, M., Nauka, 1975. Online
• I. A. Klimishin, "Astronomy yesterday and today", Kyiv, Naukova Dumka, 1977.
• G. P. Matvievskaya, "Spherics and spherical trigonometry in antiquity and in the medieval East", Development of methods for astronomical research, Issue 8, Moscow-Leningrad, 1979. Online
• O. Neugebauer, "Exact sciences in antiquity", M., Nauka, 1968. Online
• R. Newton, "The Crime of Claudius Ptolemy", M., Science, 1985. Online
• A. Pannekoek, History of Astronomy, M., Nauka, 1966.
• I. D. Rozhansky, “The development of natural science in the era of antiquity. Early Greek science of nature”, M., Nauka, 1979.
• I. D. Rozhansky, "History of natural science in the era of Hellenism and the Roman Empire", M., Nauka, 1988.
• S. I. Seleshnikov, "History of the calendar and chronology", M., Nauka, 1977.
• P. Tannery, "The first steps of ancient Greek science", St. Petersburg, 1902.
• Yu. V. Tchaikovsky, "Pre-Platonic Astronomy and Copernicus", Historical and Astronomical Research, vol. XXX, M., Nauka, 2005, p. 159-200.
• A. Aaboe, Scientific Astronomy in Antiquity, Phil. Trans. R. Soc. Lond. A, V. 276, pp. 21-42, 1974.
• E.J. Aiton, "Celestial spheres and circles," History of Science, Vol. 19, pp. 76-114, 1981. Online
• J. Christianidis, D. Dialetis and K. Gavroglu, "Having a Knack for the Non-intuitive: Aristarchus's Heliocentrism through Archimedes's Geocentrism", History of Science, V. 40, Part 2, No. 128, June 2002, 147-168.
• D.R. Dicks, "Early greek astronomy to Aristotle", Cornell Univ. Press: Ithaca, New York.
• J.L.E. Dreyer, "History of the planetary systems from Thales to Kepler", Cambridge University Press, 1906. PDF
• D. Duke, "The Equant in India: The Mathematical Basis of Ancient Indian Planetary Models", Arch. Hist. Exact Sci., V.59, pp. 563-576, 2005.
• J. Dutka, "Eratosthenes" measurement of the Earth reconsidered", Arch. Hist. Exact Sci., 46, pp. 55-66, 1993. Online
• D. Engels, "The length of Eratosthenes" stade", American J. of Philology, V. 106, pp. 298-311, 1985.
• J. Evans, "The history and practice of ancient astronomy", New York: Oxford University Press, 1998.
• J. Evans, "The material culture of Greek astronomy", Journal of the History of Astronomy, V. 30, pp. 238-307, 1999. Online
• A. Gregory, "Plato and Aristotle on eclipses," Journal of the History of Astronomy, V. 31, pp. 245-259, 2000. Online
• T.L. Heath, "Aristarchus of Samos, the ancient Copernicus: a history of Greek astronomy to Aristarchus", Oxford, Clarendon, 1913; reprinted New York, Dover, 1981. PDF
• B.R. Goldstein and A.C. Bowen, "A new view of early Greek astronomy", Isis, V.74(273), pp. 330-340, 1983.
• B.R. Goldstein and A.C. Bowen, "The introduction of dated observations and precise measurement in Greek astronomy", Arch. Hist. Exact Sci., V.43(2), pp. 93-132, 1991.
• A. Jones, "The adaptation of Babylonian methods in Greek numerical astronomy", Isis, V.82(313), pp. 441-453, 1991.
• A. Jones, "Ptolemy's Ancient Planetary Observations", Annals of science, Vol. 63, no. 3, July 2006, 255-290.
• W.R. Knorr, "Plato and Eudoxus on planetary motions", Journal of the History of Astronomy, V.21, pp. 314-329, 1990. Online
• Y. Maeyama, "Ancient stellar observations: Timocharis, Aristyllus, Hipparchus, Ptolemy - the dates and accuracies", Centaurus, V.27(3-4), pp. 280-310, 1984.
• O. Neugebauer, "The History of Ancient Astronomy: Problems and Methods", Journal of Near Eastern Studies, V.4, No.1, pp. 1-38, 1945. Part 1 Part 2
• O. Neugebauer, "Mathematical methods in ancient astronomy", Bull. amer. Math. soc. Volume 54, Number 11, Part 1 (1948), 1013-1041. PDF
• D. Pingree, "On the Greek Origin of the Indian Planetary Model Employing a Double Epicycle", Journal for the History of Astronomy, Vol. 2, pp. 80-85, 1971. Online
• D. Rawlins, "Ancient geodesy: achievements and corruption", Vistas in astronomy, Vol. 28, pp. 255-268, 1985.
• D. Rawlins, "Ancient Heliocentrists, Ptolemy, and the equant", American Journal of Physics, V.55, pp. 235-239, 1987. Online
• D. Rawlins, "Hipparchos" ultimate solar orbit", DIO, V. 1.1, pp. 49-66, 1991. Journal website
• D. Rawlins, "Continued-Fraction Decipherment: Ancestry of Ancient Yearlengths and pre-Hipparchan Precession", DIO, V. 9.1, 1999. Journal website
• D. Rawlins, "Aristarchos and the "Babylonian" System B Month", DIO, V. 11.1, 2002. Journal website
• D. Rawlins, Aristarchos Unbound: Ancient Vision, DIO, V.14, 2008.
• L. Russo, "The astronomy of Hipparchus and his time: A study based on pre-ptolemaic sources", Vistas in astronomy, V. 38, Pt 2, pp. 207-248, 1994.
• L. Russo, "The forgotten revolution: how science was born in 300 BC and why it had to be reborn", Berlin: Springer 2004.
• N.M. Swerdlow, "Hipparchus on the distance of the sun," Centaurus, v. 14, pp. 287-305, 1969.
• H. Thurston, "Greek mathematical astronomy reconsidered", Isis, V.93, pp. 58-69, 2002.
• H. Thurston, "Early astronomy", New York, Springer-Verlag: 1994.
• G.J. Toomer, "Hipparchus on the distances of the Sun and Moon", Arch. Hist. Exact Sci., 14, pp. 126-142, 1974. Online
• B.L. van der Waerden, The Earliest Form of the Epicycle Theory, Journal of the History of Astronomy, Vol. 5, p.175-185, 1974. Online
• B.L. van der Waerden, "On the motion of the planets according to Heraclides of Pontus", Arch. Internat. Hist. Sci., v. 28(103), pp. 167-182, 1978. Russian translation
• B.L. van der Waerden, "The Motion of Venus, Mercury and the Sun in Early Greek Astronomy", Archive for History of Exact Sciences, Volume 26(2), pp. 99-113, 1982. Online
• B.L. van der Waerden, Greek astronomical calendars. III. The calendar of Dionysios, Arch. Hist. Exact Sci., V.29(2), pp. 125-130, 1984. Online
• B.L. van der Waerden, "The heliocentric system in Greek, Persian and Hindu astronomy", in "From deferent to equant: A Volume of Studies in the History of Science in the Ancient and Medieval Near East in Honor of E.S. Kennedy, Annals of the New York Academy of Sciences, Volume 500, June 1987, 525-545.

4. MATHEMATICS, ASTRONOMY, GEOGRAPHY AND ACTIVITIES OF ALEXANDRIAN SCIENTISTS

The level of knowledge about nature absorbed the results of the previous development of natural philosophy in the classical and Hellenistic periods. Despite the development of new areas of theoretical and applied knowledge during the period of the Empire, in terms of method, concepts, choice of problems, astronomy, mathematics and geography proceeded from the scientific tradition accumulated by previous generations. In turn, interest in mathematics and astronomy was also due to the fact that the knowledge acquired in these areas of science contributed to the practical development of navigation (outside the Mediterranean basin), as well as all kinds of land surveying.

Greek mathematicians of the 5th-4th centuries. BC e. already used elements of higher mathematics. Eudoxus laid the foundation for an axiomatic direction, different from the methods of South Italian and Ionian mathematical schools. Together with the creation of "geometric algebra", the axiomatic style contributed to the further development of Greek mathematical theory. Euclid's "Elements" summed up the previous development of Greek mathematics. 13 books of his work included planimetry, number theory, the doctrine of incommensurable quantities and stereometry. Euclid's geometry, which used theorems, axioms, definitions, postulates, until recently met the requirements of a school manual.

The greatest mechanic, mathematician and astronomer was Archimedes (287-212), who lived in the South Italian Greek colony of Syracuse in Sicily at the court of his relative the tyrant Hieron. The mathematical and mechanical studies of Archimedes amazed his contemporaries, and many historical and legendary testimonies have been preserved about him, one of which is reported by Vitruvius, a mechanic and architect of the time of Augustus: “When Hieron, who reached royal power in Syracuse, after the successful completion of his enterprises, he decided, on a vow to the immortal gods, to place a golden crown in one of the temples, he ordered it to be made for a fee and weighed the right amount of gold to the contractor. At the time appointed by the contract, he delivered to the tsar a finely executed work, apparently exactly corresponding to the weight of the gold allotted for it. After the denunciation was made that part of the gold was concealed and the same amount of silver was mixed into it during the manufacture of the crown, Hiero, indignant at the insult inflicted on him and not finding a way to prove this loss, turned to Archimedes with a request to take over resolution of this issue. It so happened that while Archimedes was pondering this, he went to the bathhouse, and as he sat down in the bath he noticed that the deeper he immersed himself in it with his body, the more water flowed over the edge. And as soon as this showed him the way to resolve this issue, he jumped out of the bath without hesitation, overjoyed and rushed naked to his house, shouting loudly that he had found what he was looking for; for as he ran, he continually exclaimed in Greek: "Eureka, eureka!" (IX, praef., 9-10). It was as if the second law of hydrodynamics had been discovered, on the basis of which Archimedes was able to prove the unscrupulousness of the contractor by doing an experiment that showed an admixture of silver in the golden crown. Archimedes was the first to determine the ratio of circumference to diameter, and also determined that the surface of a sphere with radius r is equal to 4r2n. He defined the value of l as 3 10/70 > n > 3 10/71.

The greatest mathematician, astronomer and geographer was Eratosthenes of Cyrene (270-194 BC), head of the Library of Alexandria. We have received his letter to Ptolemy III Euergetes about doubling the cube. In the next century, there lived the greatest astronomer and mathematician, the founder of trigonometry, Hipparchus of Tarentum (190–120 BC), who proposed a spherical coordinate system that greatly influenced the geocentric theory of Claudius Ptolemy. By the time of the Roman Empire, there was a tendency in mathematical theories towards algebraic and arithmetic forms, which is manifested, in particular, in the absence of a strictly axiomatic structure in the geometry of Heron of Alexandria and the arithmetic-algebraic direction of Diophantus of Alexandria. In 13 books of "Arithmetic" of the "father of algebra", of which only six have come down to us, solutions of equations of the second degree, cubic and biquadratic, equations are given (the famous "Diophantine Equations").

In the III century. BC e. Aristarchus of Samos made an attempt to determine the relative sizes of the Earth, Moon and Sun, as well as the distances between them, and put forward the heliocentric concept of planetary motion. Big influence subsequent generations of astronomers and geographers were influenced by the observations of Eratosthenes and Seleucus (II century BC) on the dependence of oceanic tides on the annual rotation of the Earth around its axis and on the position of the Moon. Seleucus suggested the infinity of the universe. Archimedes was also involved in calculating the apparent diameter of the Sun and even built a model that reproduced the movement of the Moon, the Sun and the five planets, in fact, the first known planetarium that Cicero saw in Rome.

The main astronomical and meteorological ideas of the Early Empire were outlined by the Roman author of the time of Augustus Manilius in the didactic poem "Astronomics". Lucretius, Vitruvius, Pliny the Elder, Seneca also touched upon astronomical problems in their encyclopedias. In the science of the period of the Empire, the generally accepted point of view was that the universe revolves around the motionless Earth, which occupies a central position in the universe. The earth is spherical and rotates around its axis passing through the center of the universe. Claudius Ptolemy also adhered to the traditional view of the motionless Earth at the center of the Universe, substantiating this position by the consistent application of trigonometry and all previous mathematics. He also rejected the hypothesis of the rotation of the Earth around its axis: numerous, carefully selected and analyzed empirical data in his constructions were much easier to explain by a geocentric epicycle than by a heliocentric planetary system.

In close connection with the astronomical theories of that time was astrology, which was very widespread by the 2nd century BC. n. e. Not only private individuals resorted to astrological predictions, from the slave to the emperor. Philosophy and medicine experienced the impact of astrology. Mineralogy, botany and other natural sciences. If the New Academy "read the foundations of this science as untenable, then the Stoics were very supportive of it, not making much difference between the concepts of" astrology "and" astronomy ". Hellenistic personal astrology, which probably arose in the 3rd century BC. BC e. in the school of Berossus on the island of Kos, was not a direct borrowing or an improved form of Babylonian astrology. Hellenistic astrological theories are based on the idea that it is possible to predict future events for a certain person by calculating the position space bodies and signs of the zodiac at the time of birth. They did not see anything supernatural in such logic, if we take into account that in a philosophically comprehended picture of the world, the cosmos is a single closed system, all parts of which are interconnected and interdependent. Seneca, for example, represented the universe as a structure-like whole of events that have already taken place and are still hidden in the future (NQ, II, 3, 1). Among the eight books of Sextus Empiricus against scientists, on equal grounds, there is also a book against astrologers. Astrologers often found themselves in the same status as philosophers when they were repeatedly expelled from Rome by official decrees. The fact that many Roman emperors kept astrologers with them in their official positions is explained by the natural desire for a politician to correctly assess the future alignment of forces, so that the astrologer's predictions in this case are a kind of futurology at the level of knowledge of that time. The mass consciousness often confused astrologers with street fortune-tellers, charlatans and magicians, which was a consequence of the extreme spread of religious and mystical beliefs among the lower population of the empire.

Theoretical astronomy and astrology Claudius Ptolemy combined with mathematics, which gives a more reliable explanation of natural phenomena due to the fact that it is based not on direct experience, but on experience interpreted with the help of mathematical constructions, and operates with methods of arithmetic and logical proofs (Ptol. Almagest, I , one). According to Ptolemy, there are two ways of predicting through astronomy: the first is based on the position of the interdependent relationship of the Sun, Moon and other planets with each other and all of them with the Earth (Tetrab., I, prooem.). Detailed description of this method and its application Ptolemy sets out in 13 books of the Mathematical Collection, better known in Arabic as the Almagest. The second method traces the degree and nature of the influences exerted by the planets mutually located in accordance with the natural law on the phenomena of nature dependent on them. Ptolemy's "Tetrabiblos" ("Four-armed") is devoted to a detailed consideration of this topic.

The first two books of the Almagest are devoted to the scientific (mathematical) substantiation of the above topic and the presentation of the doctrine of the celestial sphere. Book III sets out the theory of the motion of the Sun, and here Ptolemy actually follows the conclusions of Hipparchus, made three centuries earlier. The geocentric theory of Ptolemy, which attracted the attention of scientists at a later time, did not occupy the dominant position in the general system of Ptolemy's views, which began to be given to it in modern times. Books IV and V deal with the motion of the Moon, and VI with the application of the theories outlined to predict eclipses. Books VII and VIII contain a detailed list of the stars, and the last five books are devoted to the consideration of the motion of the planets.

The Tetrabiblos is a systematic exposition of astrological science. Academics, since Carneades, have criticized the foundations of astrology, and Ptolemy, building on Posidonius, who defended the science of divinations, devotes the first and second chapters of book I to the justification of astrology as a science that is as close to finding the truth as philosophy, books I and II consider "universal" astrology, the subject of which is to identify the nature of the influences of the heavenly bodies - the Sun, the Moon, etc. - on humanity, the continents and the nature of phenomena in general. We are talking about the causes and patterns of such phenomena due to the influence of the planets as annual alternations of climates, changes in wind directions, the speed of rivers, the magnitude of waves, the ebbs and flows of the seas, the rhythms of the vital activity of animals and plants, etc. These phenomena, writes Ptolemy, are well known to all those who, by occupation, are connected with agriculture or navigation and have thus developed natural observation, noting, for example, by a certain arrangement of the moon and stars in the sky, signs of an impending storm or a change in the wind. However, only natural observation cannot guarantee the infallibility of the conclusions; only the mastery of the scientific methods of astrology provides accurate knowledge of things that are naturally changeable and random. The erroneous results of applying the methods of astrology do not yet prove its imperfection as a science, but are the result of the incorrect use of astrology.

The subject of consideration of the III and IV books of the Tetrabiblos is “genetlialogical”, i.e., taking into account the innate properties of a person, astrology, the purpose of which was to clarify the dependence of the fate of an individual specific person on the relative position of the heavenly bodies at the time of his birth and after. Ptolemy notes, in particular, that in order to compile a horoscope, it is extremely important to know the exact time of a person’s birth (up to a minute), but in practice, he complains, we are forced to resort to the readings of a sun or water clock, which, unfortunately, do not have sufficient accuracy. indications (Tetrab., III, 2).

In addition to astronomy and astrology. Ptolemy also studied music theory, optics, chronography and geography. In the Almagest, he described the location of the land known in his time on the surface of the globe, and also gave information about seven "climates", or parallels, determined by the shadow on the sundial at the solstices and equinoxes. He transferred these questions to the "Guide to Geography", or, as Thomson defined it (for lack of descriptive and historical material), "Guide to Map Making". Indeed, Ptolemy has almost no physical and geographical data, which form the basis of 17 books on geography of his predecessor Strabo (1st century AD). Ptolemy's main concern in the Manual of Geography was mapping, based on astronomical location of a given point. This was a very useful undertaking, because in the practice of this time, most settlements was determined very approximately, based on the evidence of itineraries (guides) and traveler reports, very unreliable due to the lack of a compass. To describe the methods of mapping, with the help of which he indicated about 8 thousand settlements, Ptolemy attached 27 maps that have come down to us in badly damaged medieval copies.

Along with mathematics and astronomy, by the time of Ptolemy, Hellenistic geography had a great tradition.

The name of the science of the nature of the surface of the globe belongs to Eratosthenes (276-194 BC). To generalize the vast factual material accumulated by previous generations of navigators, merchants and travelers, providing these data with theoretical justifications from physics, astronomy and meteorology, a separate area of ​​\u200b\u200bknowledge - geography, or land description, has become. Eratosthenes wrote "Geographical Notes", the content of which is known mainly from the work of Strabo. Eratosthenes was the author of the first map of the Earth, taking into account its spherical shape, he also made the first attempt to accurately determine the extent of the inhabited world from north to south and from west to east, building a grid of parallel and perpendicular lines. Eratosthenes also owns the definition of the circumference of the Earth, which is very close to the true one, using a special type of sundial, “skafis” or “skiaferon”. He described this procedure in the work “On the Measurement of the Earth”, which has not survived to our time. Referring to Eratosthenes, ancient authors give the figure of 252,000 stadia for the circumference of the Earth, i.e., about 39,690 km (the actual length of the meridian is 40,000 km). The famous Stoic Posidonius (c. 135-51 BC) made another attempt to measure the circumference of the earth, receiving a figure of 180 thousand stadia.

During the period of the Roman Empire, the information of Eratosthenes, Hipparchus and Posidonius was summarized by Strabo (63 BC - 19 AD), a native of the Greek colony of Amasia on the southern coast of Pontus, in 17 books of his Geography. Strabo traveled a lot, collected a huge amount of material and gave a description of all the then known ecumene. Strabo also took into account the new data obtained by the Romans as a result of the conquest of the previously little-known territories of Gaul, Germany and Britain. At the same time, he tried to systematize the geographical information of his predecessors, comparing them with the facts known in his time. Strabo wrote his "Geography", focusing, as they say now, "on a wide range of readers", but at the same time, not for the ignorant. He emphasized that "geography, no less than any other science, is included in the scope of the philosopher's activities" (1, 1). Strabo was also the author of a 43-volume work on history, almost completely lost to modern scholars.

Of the Roman authors who wrote in Latin for the Roman reader, Strabo's contemporaries were the author of a geographical work in three books "Description of the Localities" by Pomponius Mela; geographical information is also given by Vitruvius, Lucretius, Pliny, Seneca, the author of the historical poem "Pharsalia" Lucan, Manilius in "Astronomics" and other Roman authors.

In the Roman Empire, mathematics, astronomy, or geography were not scientific activity in the modern sense, since the ancient "scientist" was least of all a "narrow specialist" in a particular field of knowledge. The sciences of nature developed within the framework of the cognition of natural regularity by the methods inherent in ancient science, the ideological nature of which was expressed in the fact that nature was known through philosophy, precisely in that part of it associated with the whole system, which was called physics, or natural philosophy. The naturalist in the understanding of Seneca is the one who develops this particular part of philosophy the most (NQ, VI, 13, 2). Ptolemy, following Aristotle, divided theory (the speculative philosophical concept of the universe) into theology (knowledge of the deity), physics, which studies the phenomena of the sublunar world, and mathematics, including theoretical astronomy (Almagest., I, 1). Scientific knowledge was closely connected with philosophy, so the theoretical scientist was in a hurry to announce the involvement of any field of knowledge in philosophy, be it mathematics, geography, medicine or the theory of agriculture, because knowledge, divorced from the general system of philosophy, was not a science and belonged either to craft, or to a collection of information about natural anomalies, as happened, for example, with the scientific tradition of paradoxography by the time of the Empire.

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MATHEMATICS, ASTRONOMY, MEDICINE. History of culture of ancient Greece and Rome

MATHEMATICS, ASTRONOMY, MEDICINE

Both the Platonic Academy and the Lyceum had an undeniable influence on natural Sciences that time. Plato himself considered mathematics one of the most important areas of knowledge, and it is not surprising that Theudius of Magnesia, the author of a mathematics textbook, came out of his Academy. The outstanding astronomer and geographer Eudoxus from the island of Cnidus, who had previously received education from worshipers of numbers - the Pythagoreans, also studied at the Academy; the merits of Eudoxus include the development of a new method mathematical analysis, a new definition of proportionality, as well as the recognition of the sphericity of the Earth and attempts, albeit unsuccessful, to calculate the length of its circumference. Among many other well-known mathematicians of that time, let us mention another student of the Pythagoreans, Archytas, whom the ancients themselves considered the creator of scientific mechanics.

The success of medicine is evidenced by a fragment of the work of the largest physician of the 4th century. BC e. Diocles of Carist. It contains instructions on how to properly build your day in order to maintain health, in relation to a particular season. There are also prescriptions concerning body hygiene, diet, preferred leisure activities. This writing differs markedly in its rationalistic spirit from contemporary inscriptions found in the temple of Asclepius in Epidaurus, where recovered people describe the course of the disease and their healing thanks to some miracle. So, one woman tells how she was pregnant for five years, after which she gave birth to a boy, and he immediately bathed in the source and ran after his mother. And there are many similar stories to be found there, in which the contemporaries of mathematicians and rationalist doctors continued to firmly believe.

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Ancient Greece and Ancient Rome

Main article: Astronomy of ancient Greece

In ancient Greece of the pre-Hellenistic and early Hellenistic periods, the names of the planets were not related to deities: Saturn was called Fainon, ʼʼbrightʼʼ, Jupiter - Phaethon, Mars - Piroeis, ʼʼfieryʼʼ; Venus was known as Phosphoros, ʼʼHerald of Lightʼʼ (during morning visibility) and Hesperos (during evening visibility), and the most rapidly disappearing Mercury as Stilbon.

But later, apparently, the Greeks adopted the ʼʼdivineʼʼ names of the planets from the Babylonians, but remade them to suit their pantheon. Enough correspondence has been found between the Greek and Babylonian naming traditions to suggest that they did not originate separately from each other. The translation was not always accurate. For example, the Babylonian Nergal is the god of war, thus the Greeks associated him with Ares. But unlike Ares, Nergal was also the god of pestilence, pestilence, and the underworld. Later, the ancient Romans, along with culture and ideas about the world around them, copied the names of the planets from the ancient Greeks. This is how Jupiter, Saturn, Mercury, Venus and Mars familiar to us appeared.

Many Romans followed the belief, probably originating in Mesopotamia but reaching its final form in Hellenistic Egypt, that the seven gods after whom the planets were named took care of the earth's hourly changes. The order began Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon (from the most distant to the closest). Therefore, the first day began with Saturn (1st hour), the second day with the Sun (25th hour), followed by the Moon (49th hour), then Mars, Mercury, Jupiter and Venus. Since each day was named after the god with which it began, this order was preserved in the Roman calendar after the abolition of the ʼʼMarket cycleʼʼ - and is still preserved in many modern languages.

The term ʼʼplanetʼʼ comes from the ancient Greek πλανήτης, which meant ʼʼwandererʼʼ, the so-called object that changed its position relative to the stars. Since, unlike the Babylonians, the ancient Greeks did not attach importance to predictions, the planets were initially not particularly interested. Pythagoreans, in the VI and V centuries BC. e. developed their own independent planetary theory, according to which the Earth, Sun, Moon and planets revolve around the "Central Fire", which was taken as the theoretical center of the Universe. Pythagoras or Parmenides were the first to identify the ʼʼeveningʼʼ and ʼʼmorningʼʼ (Venus) as the same object.

In the III century BC. e, Aristarchus of Samos proposed a heliocentric system, according to which the Earth and other planets revolved around the Sun. At the same time, geocentrism remained dominant until the Scientific Revolution. It is possible that the Antikythera mechanism was an analog computer designed to calculate the approximate positions of the sun, moon, and planets on a given date.

By the 1st century BC. e, during the Hellenistic period, the Greeks began to create their own mathematical schemes for predicting the position of the planets. The ancient Babylonians used arithmetic [source not specified 259 days], while the scheme of the ancient Greeks was based on geometric solutions [source not specified 259 days]. This approach made it possible to advance far in explaining the nature of the movement of celestial bodies visible to the naked eye from the Earth. These theories are most fully reflected in the Almagest, written by Ptolemy in the 2nd century AD. e. The dominance of the Ptolemaic model was so complete that it eclipsed all previous work on astronomy and remained the most authoritative astronomical work in the Western world for 13 centuries. The complex of Ptolemy's laws well described the characteristics of the orbits of the 7 planets, which, according to the Greeks and Romans, revolved around the Earth. In order of increasing distance from the Earth, according to the scientific community of that time, they were located as follows: the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn.

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Astronomy of ancient Greece - page 2

But this was only the first success of the remarkable astronomer Aristarchus of Samos. It fell to him to observe a total solar eclipse when the disk of the Moon covered the disk of the Sun, i.e., the apparent sizes of both bodies in the sky were the same. Aristarchus rummaged through the old archives, where he found a lot of additional information about eclipses. It turned out that in some cases solar eclipses were annular, that is, a small luminous rim from the Sun remained around the disk of the Moon (the presence of total and annular eclipses is due to the fact that the Moon's orbit around the Earth is an ellipse). But if the visible disks of the Sun and the Moon in the sky are almost the same, Aristarchus reasoned, and the Sun is 19 times farther from the Earth than the Moon, then its diameter should be 19 times larger. What is the relationship between the diameters of the Sun and the Earth? According to many data on lunar eclipses, Aristarchus established that the lunar diameter is approximately one third of the earth's and, therefore, the latter should be 6.5 times less than the solar one. At the same time, the volume of the Sun should be 300 times the volume of the Earth. All these arguments distinguish Aristarchus of Samos as an outstanding scientist of his time. He went further in his constructions, starting from the results obtained. Then it was generally accepted that the Moon, planets, the Sun and stars revolve around the motionless Earth (the center of the world) under the influence of Aristotle's "first mover". But can the huge Sun revolve around the small Earth? Or an even larger universe? And Aristotle said no, he can't. The sun is the center of the universe, the earth and planets revolve around it, and only the moon revolves around the earth. Why does day turn into night on Earth? And Aristarchus gave the correct answer to this question - the Earth not only revolves around the Sun, but also rotates around its axis. And he answered one more question perfectly. Let us give an example with a moving train, when external objects close to the passenger run past the window faster than distant ones. The earth moves around the sun, but why does the star pattern stay the same? Aristotle replied: "Because the stars are unimaginably far from the small Earth." The volume of the sphere of fixed stars is so many times greater than the volume of a sphere with a radius of the Earth - the Sun, how many times the volume of the latter is greater than the volume of the globe. This new theory was called heliocentric, and its essence was that the motionless Sun was placed in the center of the Universe and the sphere of stars was also considered motionless. Archimedes in his book “Psamit”, an excerpt from which is given as an epigraph to this essay, accurately conveyed everything that Aristarchus proposed, but he himself preferred to “return” the Earth to its old place again. Other scholars have completely rejected the theory of Aristarchus as implausible, and the idealist philosopher Cleanthes simply accused him of blasphemy. The ideas of the great astronomer did not find a basis for further development at that time, they determined the development of science for about one and a half thousand years and then revived only in the works of the Polish scientist Nicolaus Copernicus. The ancient Greeks believed that poetry, music, painting and science were patronized by nine muses, who were the daughters of Mnemosyne and Zeus. So, the muse Urania patronized astronomy and was depicted with a crown of stars and a scroll in her hands. Clio was considered the muse of history, Terpsichore was the muse of dances, Melpomene was the muse of tragedies, etc. The Muses were the companions of the god Apollo, and their temple was called the museumon - the house of the Muses. Such temples were built both in the metropolis and in the colonies, but the Alexandrian Museum became an outstanding academy of sciences and arts of the ancient world. Ptolemy Lag, being a persistent man and wanting to leave a memory of himself in history, not only strengthened the state, but also turned the capital into a trading center for the entire Mediterranean, and the Museum into a scientific center of the Hellenistic era. The huge building housed a library, a higher school, an astronomical observatory, a medical anatomical school and a number of other scientific departments. The museum was government agency, and its expenses were provided by the corresponding budget item. Ptolemy, like Ashurbanipal in Babylon in his time, sent scribes throughout the country to collect cultural treasures. In addition, each ship entering the port of Alexandria was obliged to transfer to the library the information on board. literary works. Scientists from other countries considered it an honor to work in scientific institutions Museumon and leave your work here. For four centuries, the astronomers Aristarchus of Samos and Hipparchus, the physicist and engineer Heron, the mathematicians Euclid and Archimedes, the doctor Herophilus, the astronomer and geographer Claudius Ptolemy and Eratosthenes worked in Alexandria, who was equally successful in mathematics, geography, astronomy, and philosophy. But the latter was rather an exception, since an important feature of the Hellenic era was the "differentiation" of scientific activity. Here it is curious to note that such a separation of individual sciences, and in astronomy and specialization in certain areas, occurred in ancient China much earlier. Another feature of Hellenic science was that it again turned to nature, i.e. she began to "extract" the facts herself. The Encyclopedists of Ancient Hellas relied on information obtained by the Egyptians and Babylonians, and therefore were engaged only in the search for the causes that cause certain phenomena. The science of Democritus, Anaxagoras, Plato and Aristotle was even more speculative, although their theories can be regarded as the first serious attempts of mankind to understand the structure of nature and the entire Universe. The Alexandrian astronomers closely followed the movements of the Moon, the planets, the Sun, and the stars. The complexity of planetary movements and the richness of the stellar world forced them to look for starting points from which systematic research could begin. "Phaenomena" Euclid and the main elements of the celestial sphere As mentioned above, the Alexandrian astronomers tried to determine the "starting" points for further systematic research. In this regard, special merit belongs to the mathematician Euclid (III century BC), who in his book "Phaenomena" first introduced concepts into astronomy that had not been used in it until then. So, he gave definitions of the horizon - a great circle, which is the intersection of a plane perpendicular to the plumb line at the point of observation, with the celestial sphere, as well as the celestial equator - a circle obtained by intersecting the plane of the earth's equator with this sphere. In addition, he determined the zenith - the point of the celestial sphere above the observer's head ("zenith" is an Arabic word) - and the point opposite to the zenith point - the nadir. And Euclid spoke about one more circle. This is the celestial meridian - a large circle passing through the Pole of the World and the zenith. It is formed at the intersection with the celestial sphere of a plane passing through the axis of the world (axis of rotation) and a plumb line (ie, a plane perpendicular to the plane of the earth's equator). Regarding the meaning of the meridian, Euclid said that when the Sun crosses the meridian, noon comes in this place and the shadows of objects are the shortest. To the east of this place, noon on the globe has already passed, and to the west it has not yet arrived. As we remember, the principle of measuring the shadow of a gnomon on Earth for many centuries underlay the design of sundials. The brightest "star" of the Alexandrian sky Earlier we already got acquainted with the results of the activities of many astronomers, both famous and those whose names have sunk into oblivion. Even thirty centuries before the new era, Heliopolis astronomers in Egypt established the length of the year with amazing accuracy. Curly-bearded priests - astronomers, who observed the sky from the tops of the Babylonian ziggurats, were able to draw the path of the Sun among the constellations - the ecliptic, as well as the celestial paths of the Moon and stars. In distant and mysterious China, the inclination of the ecliptic to the celestial equator was measured with high accuracy. Ancient Greek philosophers sowed seeds of doubt about the divine origin of the world. Under Aristarchus, Euclid and Eratosthenes, astronomy, which until then had given away most of the astrology, began to systematize its research, standing on the firm ground of true knowledge. And yet, what Hipparchus did about the field of astronomy far exceeds the achievements of both his predecessors and scientists of a later time. With good reason, Hipparchus is called the father of scientific astronomy. He was extremely punctual in his research, repeatedly checking the conclusions with new observations and striving to discover the essence of the phenomena occurring in the Universe. The history of science does not know where and when Hipparchus was born; it is only known that the most fruitful period of his life falls on the time between 160 and 125 years. BC e. He spent most of his research at the Alexandria Observatory, as well as at his own observatory built on the island of Samos. Even before the Hipparchatheory of the celestial spheres, Eudoxus and Aristotle were rethought, in particular, by the great Alexandrian mathematician Apollonius of Perga (3rd century BC), but the Earth still remained at the center of the orbits of all celestial bodies. Hipparchus continued the development of the theory of circular orbits begun by Apollonius, but made significant additions to it, based on long-term observations. Earlier, Calippus, a student of Eudoxus, discovered that the seasons were not of the same length. Hipparchus checked this statement and clarified that astronomical spring lasts 94 and 1/2 days, summer - 94 and 1/2 days, autumn - 88 days and, finally, winter lasts 90 days. Thus, the time interval between the spring and autumn equinoxes (including summer) is 187 days, and the interval from the autumn equinox to the spring equinox (including winter) is 88 + 90 = 178 days. Consequently, the Sun moves unevenly along the ecliptic - slower in summer and faster in winter. Another explanation of the reason for the difference is also possible, if we assume that the orbit is not a circle, but an “elongated” closed curve (Appolonius of Perga called it an ellipse). However, to accept the non-uniformity of the Sun's motion and the difference of the orbit from a circular one meant to turn upside down all ideas that had been established since the time of Plato. Therefore, Hipparchus introduced a system of eccentric circles, assuming that the Sun revolves around the Earth in a circular orbit, but the Earth itself is not at its center. The unevenness in this case is only apparent, because if the Sun is closer, then the impression of its faster movement arises, and vice versa. However, for Hipparchus, the direct and backward movements of the planets remained a mystery, i.e. the origin of the loops that the planets described in the sky. Changes in the apparent brightness of the planets (especially for Mars and Venus) testified that they also move along eccentric orbits, now approaching the Earth, now moving away from it and changing brightness accordingly. But what is the reason for forward and backward movements? Hipparchus came to the conclusion that placing the Earth away from the center of the planets' orbits was not enough to explain this mystery. Three centuries later, the last of the great Alexandrians, Claudius Ptolemy, noted that Hipparchus abandoned the search for this direction and limited himself to systematizing his own observations and those of his predecessors. It is curious that at the time of Hipparchus, the concept of an epicycle already existed in astronomy, the introduction of which is attributed to Apollonius of Perga. But, one way or another, Hipparchus did not engage in the theory of planetary motion. But he successfully modified the method of Aristarchus, which makes it possible to determine the distance to the Moon and the Sun. The spatial arrangement of the Sun, Earth and Moon during a lunar eclipse when observations were made. Hipparchus also became famous for his work in the field of stellar research. He, like his predecessors, believed that the sphere of fixed stars really exists, i.e. objects located on it are at the same distance from the Earth. But why then are some of them brighter than others? Because, Hipparchus believed, that their true sizes are not the same - than more star, the brighter it is. He divided the brightness range into six values, from the first to the most bright stars up to the sixth - for the weakest, still visible to the naked eye (naturally, there were no telescopes then). In the modern scale of stellar magnitudes, a difference of one magnitude corresponds to a difference in radiation intensity of 2.5 times. In 134 BC. e. a new star shone in the constellation Scorpio (now it has been established that new stars are binary systems in which an explosion of matter occurs on the surface of one of the components, accompanied by a rapid increase in the brightness of the object, followed by decay). Previously, there was nothing at this place, and therefore Hipparchus came to the conclusion that it was necessary to create an accurate star catalog. With extraordinary care, the great astronomer measured the ecliptic coordinates of about 1000 stars, and also estimated their magnitudes on his scale. While doing this work, he decided to test the opinion that the stars are fixed. More precisely, the descendants should have done it. Hipparchus compiled a list of stars in a straight line, in the hope that future generations of astronomers would test to see if the line remained straight. While compiling the catalog, Hipparchus made a remarkable discovery. He compared his results with the coordinates of a number of stars measured before him by Aristylus and Timocharis (contemporaries of Aristarchus of Samos), and found that the ecliptic longitudes of objects increased by about 2º over 150 years. At the same time, the ecliptic latitudes did not change. It became clear that the reason was not in the proper motions of the stars, otherwise both coordinates would have changed, but in the movement of the vernal equinox point, from which the ecliptic longitude is measured, and in the direction opposite to the movement of the Sun along the ecliptic. As you know, the vernal equinox is the intersection of the ecliptic with the celestial equator. Since the ecliptic latitude does not change with time, Hipparchus concluded that the reason for the shift of this point is the movement of the equator. Thus, we have the right to be surprised at the extraordinary consistency and rigor in the scientific research of Hipparchus, as well as their high accuracy. The French scientist Delambre, a well-known researcher of ancient astronomy, described his activities as follows: “When you take a look at all the discoveries and improvements of Hipparchus, reflect on the number of his works and the many calculations given there, you willy-nilly classify him among the most prominent people of antiquity and, moreover, call the greatest among them. Everything he achieved belongs to the field of science, where geometric knowledge is required, combined with an understanding of the essence of phenomena that can be observed only if tools are carefully made ... ”Calendar and stars In ancient Greece, as in the countries of the East, the lunar was used as a religious and civil - solar calendar. In it, the beginning of each calendar month was to be located as close as possible to the new moon, and average duration calendar year - if possible, correspond to the time interval between the spring equinoxes (“tropical year”, as it is now called). At the same time, months of 30 and 29 days alternated. But 12 lunar months are about a third of a month shorter than a year. Therefore, in order to fulfill the second requirement, from time to time it was necessary to resort to intercalations - to add an additional, thirteenth, month in some years. Insertions were made irregularly by the government of each policy - the city-state. For this, special persons were appointed who monitored the magnitude of the lag of the calendar year from the solar year. In Greece divided into small states, calendars had a local meaning - there were about 400 names of months in the Greek world. The mathematician and musicologist Aristoxenus (354-300 BC) wrote about the calendar disorder: “The tenth day of the month among the Corinthians is the fifth day by the Athenians and the eighth by someone else” Athenian astronomer Meton. This cycle included the insertion of seven additional months in 19 years; his error did not exceed two hours per cycle. Farmers associated with seasonal work, since ancient times, also used the stellar calendar, which did not depend on the complex movements of the Sun and Moon. Hesiod in the poem “Works and Days”, indicating to his brother Persian the time of agricultural work, marks them not according to the lunisolar calendar, but according to the stars: Only in the east the Pleiades Atlantis will begin to rise, Harvest quickly, but they will begin to Set - start sowing ... Here, high in the sky, Sirius has risen with Orion, The pink-fingered dawn is already beginning to See Arthur, Cut, O Persian, and take home Grape bunches ... Thus, a good knowledge of the starry sky, which in modern world few people can boast, the ancient Greeks were necessary and, obviously, widespread. Apparently, this science was taught to children in families with early age. The lunisolar calendar was also used in Rome. But even more “calendar arbitrariness” reigned here. The length and beginning of the year depended on the pontiffs (from the Latin Pontifices), Roman priests, who often used their right for selfish purposes. Such a situation could not satisfy the huge empire into which the Roman state was rapidly turning. In 46 BC Julius Caesar (100-44 BC), who acted not only as the head of state, but also as the high priest, carried out a calendar reform. The new calendar, on his behalf, was developed by the Alexandrian mathematician and astronomer Sosigen, a Greek by origin. He took the Egyptian, purely solar, calendar as a basis. The refusal to take into account the lunar phases made it possible to make the calendar quite simple and accurate. This calendar, called the Julian, was used in the Christian world until the introduction of the updated Gregorian calendar in the Catholic countries in the 16th century. The Julian calendar began in 45 BC. The beginning of the year was moved to January 1 (earlier the first month was March). In gratitude for the introduction of the calendar, the Senate decided to rename the month quintilis (fifth), in which Caesar was born, into Julius - our July. In 8 BC the honor of the next emperor, Octivian Augustus, the month sextilis (sixth), was renamed August. When Tiberius, the third princeps (emperor), was asked by the senators to name the month of Septembre (seventh) after him, he allegedly refused, answering: “What will the thirteenth princeps do?” The new calendar turned out to be purely civil, religious holidays, by virtue of tradition, were still celebrated in accordance with the phases of the moon. And at present, the Easter holiday is coordinated with the lunar calendar, and the cycle proposed by Meton is used to calculate its date.

Conclusion In the distant Middle Ages, Bernard of Chartres spoke golden words to his students: “We are like dwarfs sitting on the shoulders of giants; we see more and further than they, not because we have better eyesight and not because we are superior to them, but because they raised us up and increased our stature with their greatness. Astronomers of any era have always leaned on the shoulders of previous giants. Ancient astronomy occupies a special place in the history of science. It was in ancient Greece that the foundations of modern scientific thinking were laid. For seven and a half centuries, from Thales and Anaximander, who took the first steps in comprehending the Universe, to Claudius Ptolemy, who created the mathematical theory of the movement of the stars, ancient scientists have come a long way, on which they had no predecessors. Astronomers of antiquity used data obtained long before them in Babylon. However, to process them, they created completely new mathematical methods, which were adopted by medieval Arab and later European astronomers. In 1922, the International Astronomical Congress approved 88 international names for the constellations, thereby perpetuating the memory of ancient Greek myths, after which the constellations were named: Perseus, Andromeda, Hercules, etc. (about 50 constellations). The meaning of ancient Greek science is emphasized by the words: planet, comet, galaxy and the very word Astronomy.

List of used literature 1. "Encyclopedia for children". Astronomy. (M. Aksenova, V. Tsvetkov, A. Zasov, 1997) 2. “Stargazers of antiquity”. (N. Nikolov, V. Kharalampiev, 1991) 3. “Discovery of the Universe – past, present, future”. (A. Potupa, 1991) 4. “Oikumene horizons”. (Yu. Gladky, Al. Grigoriev, V. Yagya, 1990) 5. Astronomy, grade 11. (E. Levitan, 1994)

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Ancient astronomy | Archimedes and the measurement of the sky | Eratosthenes and measuring the Earth

HISTORICAL ARTICLES Ancient astronomy (part 5): Archimedes - Measuring the sky, Eratosthenes - Measuring the Earth, the Age of Rome ARCHIMEDES. SKY MEASUREMENT Archimedes of Syracuse (c. 287-212 B.C.) is not usually considered an astronomer. An outstanding mathematician, founder of statics and hydrostatics, optician, engineer and inventor, he already won great fame in ancient times. By the way, the words of the scientist that he made a mechanical discovery that would allow him to move the Earth do not refer to the law of the lever (by the time of Archimedes it was already known), but to the principle of constructing mechanical gearboxes. It was with the help of the gearbox that Archimedes "by the power of one person" moved the ship pulled ashore. In his youth, Archimedes studied in Alexandria with the mathematician Conon. It is likely that there he met the already middle-aged Aristarchus. Returning to Syracuse, the scientist became, as they would now say, the "chief military engineer" of the city. Its defense system and war machines, including "burning mirrors" and "iron paws" (manipulators that sank Roman landing craft), made the city impregnable. In his old age, he had to participate in the defense of Syracuse, which during the 2nd Punic War was besieged by the Roman commander Marcus Marcellus. The city held out for more than a year and was captured only as a result of betrayal. During the sack of Syracuse, Archimedes was killed by a Roman soldier. The general views of the scientist on the world can be judged by his essay "On Floating Bodies". Archimedes, on the one hand, recognized the existence of atoms, on the other hand, he followed Aristotle's idea of ​​gravitation. In one of his works, Archimedes described the measurement of the angular diameter of the Sun. For this, the scientist used a horizontal ruler with a cylinder placed on it. The ruler was aimed at the luminary at its rising, "when you can look at the Sun." Looking along the ruler, Archimedes moved the cylinder along it and noted its positions when it almost covered the solar disk and when it completely covered it. Thus, a "fork" was obtained, within which the measured value lay. The result of Archimedes - 27" and 32.5" - covered the actual value of the angular diameter of the Sun - 32". The Roman historian Titus of Livy, speaking of the siege of Syracuse, calls Archimedes "the only observer of the sky and stars of his kind." Perhaps this characteristic is associated with the famous technical creation of the scientist - a mechanical celestial globe, brought to Rome as a trophy. Unlike the usual Archimedean globe, it showed not only the rotation of the sky, but also the movements of other luminaries. Apparently, along the belt of the zodiac constellations there were a number of windows behind which models of luminaries moved, set in motion by gears and air turbines. Archimedes even wrote the book "On the Structure of the Celestial Globe", which, alas, has not come down to us. This book is associated with a list of cosmic distances calculated by the scientist between the Earth, the Sun, and the planets. Distances are given in stages (one stage is 150-190 m). The numbers do not converge with each other (distances are not obtained from the sum of the intervals) and look mysterious. But recently it has been found that they make sense if some of them are attributed to the heliocentric system. The scientist correctly determined the relative distance to the Moon and the size of the orbits of Mercury, Venus and Mars, if we consider them heliocentric. The Roman architect Vitruvius, for example, mentions the mixed system of the world (geocentric, but with the circulation of Mercury and Venus around the Sun) as well-known. Probably Archimedes was its author. The first correct determination of the distances to the planets made by the scientist turned out to be in antiquity and the last. The geocentric system did not provide such opportunities. ERATOSPHENES. EARTH MEASUREMENT Archimedes corresponded with the scientists of Alexandria. After the death of his teacher Conon, he sent mathematical writings to Eratosthenes, who at that time headed the Mouseion, a scientific center in Alexandria. Eratosthenes of Cyrene (circa 276-194 BC) was a versatile scientist - mathematician, philologist, geographer. to his most important scientific achievements refers to the measurement of the circumference of the globe. Living in Egypt, the scientist knew that Siena (now Aswan) lies on the Northern Tropic. Such a conclusion followed from the fact that at noon on the day of the summer solstice the light there illuminates the bottom of deep wells, that is, it stands at its zenith. With the help of a special device, which he called "ska-fis", the scientist found that at the same time in Alexandria the Sun is 1/50 of a circle away from the vertical. Siena is on the same meridian as Alexandria; the distance between the cities was then known - about 5 thousand Egyptian stages (the distances were then measured in steps by specialists-surveyors - harpedanapts). Knowing the length of the arc and the angle it subtends, Eratosthenes multiplied the distance to Syene by 50 and obtained the circumference of the earth at 252,000 stadia. By our standards, this is 39,690 km. Given the roughness of the measuring instruments of that era and the unreliability of the initial data, the excellent agreement between the results of Eratosthenes and the real ones (40 thousand kilometers) can be considered a great success. THE ERA OF ROME In 2b4 BC. e. the Romans took possession of southern Italy with the Greek cities of Tarentum, Croton and others located there, which once constituted the region that was called Magna Graecia. Half a century later, the Greek colonies of Sicily, including the famous Syracuse, submitted to Rome, and in 146 BC. e. and Greece itself became the Roman province of Achaia. 100 years later, Julius Caesar annexed Egypt to the Roman Empire with Alexandria, the then capital of Hellenic science. Having mastered the Hellenic world, the Romans did not suppress its culture, but largely adopted it. Knowledge Greek was compulsory for educated Romans. Often they studied in Greece. Many prominent figures of Rome were educated here, for example, Tiberius Gracchus, Pompeii, Cicero, Caesar. Over time, a peculiar Greco-Roman culture developed, in line with which brilliant Latin literature developed. Rome gave the world great poets, historians, playwrights, but mathematics and astronomy were not included in its scale of values. Classes in theoretical science, unlike literary ones, were not considered prestigious. They were equated with a craft and considered unworthy of a free citizen. Many Roman politicians, such as Cicero and Caesar, were prominent men of letters. Pliny the Elder wrote an extensive work "Natural History", in which he collected a lot of natural science information, without affecting, however, the mathematical side of astronomy. This is not to say that the Romans were not at all interested in astronomy. For example, the commander Caesar Germanicus translated Arata's astronomical poem "Phenomena" from Greek into Latin. Vitruvius in his treatise "On Architecture" paid much attention to listing the types of sundials and, in connection with this, touched on the movements of the luminaries. One by one, he described two systems of the world: first he mentioned the circulation of Mercury and Venus around the Sun, then he drew a purely geocentric system, where they revolve around the Earth. Even more mysterious seems to be his mention of the "circular orbit of the Earth" dropped immediately and little connected with the text, which can serve as a hint of the author's acquaintance with the hypothesis of Aristarchus. Obviously, this knowledgeable and well-read person nevertheless does not want to understand the intricacies of astronomical theories. Remarkable astronomers worked in the Roman Empire, but the Romans themselves neglected this science. When Julius Caesar needed to reform the calendar, he invited the Greek astronomer Sosigenes from Alexandria.

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"Astronomy of Ancient Greece"

Plan

I. Introduction

II. Astronomy of the ancient Greeks

1. On the way to truth, through knowledge

2. Aristotle and the geocentric system of the world

3. The same Pythagoras

4. The first heliocentrist

5. Works of the Alexandrian astronomers

6. Aristarchus: a perfect method (his true works and successes; the reasoning of an outstanding scientist; a great theory is a failure as a consequence);

7. "Phaenomena" Euclid and the basic elements of the celestial sphere

9. Calendar and stars of ancient Greece

III. Conclusion: the role of astronomers in ancient Greece

Introduction

Assessing the path made by mankind in search of truth about the Earth, we voluntarily or involuntarily turn to the ancient Greeks. Much originated with them, but through them a lot has come down to us from other peoples. This is how history decreed: the scientific ideas and territorial discoveries of the Egyptians, Sumerians and other ancient Eastern peoples were often preserved only in the memory of the Greeks, and from them they became known to subsequent generations. A striking example of this is the detailed news about the Phoenicians, who inhabited a narrow strip of the eastern coast of the Mediterranean Sea and in the 2nd-1st millennium BC. e. who discovered Europe and the coastal regions of Northwest Africa. Strabo, a Roman scholar and Greek by birth, in his seventeen-volume Geography wrote: "Until now, the Hellenes borrow a lot from the Egyptian priests and Chaldeans." But Strabo was skeptical of his predecessors, including the Egyptians.

The heyday of Greek civilization falls on the period between the VI century BC. and the middle of the 2nd century BC. e. Chronologically, it almost coincides with the time of the existence of classical Greece and Hellenism. This time, taking into account several centuries, when the Roman Empire rose, prospered and perished, is called antique. Its initial boundary is considered to be the 7th-2nd centuries BC, when the policies-Greek city-states were rapidly developing. This form state structure became a hallmark of the Greek world.

The development of knowledge among the Greeks has no analogues in the history of that time. The scale of the comprehension of sciences can be imagined at least by the fact that in less than three centuries (!) Greek mathematics has gone its way - from Pythagoras to Euclid, Greek astronomy - from Thales to Euclid, Greek natural science - from Anaximander to Aristotle and Theophrastus, Greek geography - from Hekkatheus of Miletus to Eratosthenes and Hipparchus, etc.

The discovery of new lands, land or sea voyages, military campaigns, overpopulation in fertile areas - all this was often mythologized. In the poems, with the artistic skill inherent in the Greeks, the mythical side by side with the real. They set out scientific knowledge, information about the nature of things, as well as geographical data. However, the latter are sometimes difficult to identify with today's ideas. And, nevertheless, they are an indicator of the broad views of the Greeks on the ecumene.

The Greeks paid great attention to the concrete geographical knowledge of the Earth. Even during military campaigns, they did not leave the desire to write down everything that they saw in the conquered countries. In the troops of Alexander the Great, even special pedometers were allocated, which counted the distances traveled, compiled a description of the routes of movement and put them on the map. Based on the data they received, Dikearchus, a student of the famous Aristotle, compiled detailed map the ecumene of that time, according to him.

The simplest cartographic drawings were known even in primitive society, long before the advent of writing. This can be judged by rock paintings. The first cards appeared in ancient Egypt. On clay tablets, the contours of individual territories were drawn with the designation of some objects. Not later than 1700 BC. e. The Egyptians made a map of the developed two thousand-kilometer part of the Nile.

The Babylonians, Assyrians and other peoples of the Ancient East were also engaged in mapping the terrain ...

What did the Earth look like? What place did they assign to themselves on it? What were their ideas about the ecumene?

Astronomy of the ancient Greeks

In Greek science, the opinion was firmly established (with various variations, of course) that the Earth is like a flat or convex disk surrounded by an ocean. Many Greek thinkers did not abandon this point of view even when, in the era of Plato and Aristotle, the ideas about the sphericity of the Earth seemed to prevail. Alas, even in those distant times, the progressive idea made its way with great difficulty, demanded sacrifices from its supporters, but, fortunately, then “talent did not seem like heresy”, and “boots did not go in arguments”.

The idea of ​​a disk (drum, or even a cylinder) was very handy in confirming the widely held belief that Hellas was in the middle. It was also quite acceptable for depicting land floating in the ocean.

Within the disk-shaped (and later spherical) Earth, the ecumene stood out. Which in ancient Greek means the whole inhabited earth, the universe. The designation in one word of two seemingly different concepts (for the Greeks then they seemed to be of the same ordinal) is deeply symptomatic.

Little reliable information has been preserved about Pythagoras (VI century BC). It is known that he was born on the island of Samos; probably visited Miletus in his youth, where he studied with Anaximander; may have traveled further afield. Already in adulthood, the philosopher moved to the city of Croton and founded there something like a religious dress - the Pythagorean brotherhood, which extended its influence to many Greek cities in southern Italy. The life of the brotherhood was surrounded by mystery. There were legends about its founder Pythagoras, which, apparently, had some basis: the great scientist was no less a great politician and seer.

The basis of the teachings of Pythagoras was the belief in the transmigration of souls and the harmonious arrangement of the world. He believed that music and mental labor purifies the soul, so the Pythagoreans considered it necessary to improve in the “four arts” - arithmetic, music, geometry and astronomy. Pythagoras himself is the founder of number theory, and the theorem he proved is known today to every schoolchild. And if Anaxagoras and Democritus in their views of the world developed Anaximander's idea of ​​the physical causes of natural phenomena, then Pythagoras shared his conviction in the mathematical harmony of the cosmos.

The Pythagoreans ruled in the Greek cities of Italy for several decades, then they were defeated and moved away from politics. However, much of what Pythagoras breathed into them remained alive and had a huge impact on science. Now it is very difficult to separate the contribution of Pythagoras himself from the achievements of his followers. This applies in particular to astronomy, in which several fundamentally new ideas have been put forward. They can be judged by the meager information that has come down to us about the ideas of the late Pythagoreans and the teachings of philosophers who were influenced by the ideas of Pythagoras.

Aristotle and the first scientific picture of the world

Aristotle was born in the Macedonian city of Stagira in the family of a court physician. At the age of seventeen, he ends up in Athens, where he becomes a student of the Academy founded by the philosopher Plato.

At first, Aristotle was fascinated by Plato's system, but gradually he came to the conclusion that the views of the teacher lead away from the truth. And then Aristotle left the Academy, throwing the famous phrase: "Plato is my friend, but the truth is dearer." Emperor Philip of Macedon invites Aristotle to become the tutor of the heir to the throne. The philosopher agrees and for three years he has been constantly near the future founder great empire Alexander the Great. At the age of sixteen, his disciple led his father's army and, having defeated the Thebans in his first battle of Chaeronea, went on campaigns.

Again, Aristotle moves to Athens, and in one of the districts, called Lyceum, he opens a school. He writes a lot. His writings are so varied that it is difficult to imagine Aristotle as a solitary thinker. Most likely, during these years he acted as the head of a large school, where students worked under his leadership, just as today graduate students develop topics that are offered to them by leaders.

The Greek philosopher paid much attention to questions of the structure of the world. Aristotle was convinced that at the center of the universe, of course, is the Earth.

Aristotle tried to explain everything with reasons that are close to the common sense of the observer. So, observing the Moon, he noticed that in various phases it exactly corresponds to the form that a ball would take, on one side illuminated by the Sun. Equally rigorous and logical was his proof of the sphericity of the Earth. Having discussed everything possible reasons lunar eclipse, Aristotle comes to the conclusion that the shadow on its surface can only belong to the Earth. And since the shadow is round, then the body that casts it must have the same shape. But Aristotle is not limited to them. “Why,” he asks, “when we move north or south, do the constellations change their positions relative to the horizon?” And then he answers: “Because the Earth has a curvature”. Indeed, if the Earth were flat, wherever the observer was, the same constellations would shine over his head. It is quite another thing - on a round Earth. Here, each observer has his own horizon, his own horizon, his own sky... However, recognizing the sphericity of the Earth, Aristotle spoke out categorically against the possibility of its circulation around the Sun. “Be it so,” he reasoned, “it would seem to us that the stars are not motionless on the celestial sphere, but describe circles ...” This was a serious objection, perhaps the most serious, which was eliminated only many, many centuries later, in the 19th century.

Much has been written about Aristotle. The authority of this philosopher is incredibly high. And it is well deserved. Because, despite the rather numerous errors and misconceptions, in his writings Aristotle collected everything that the mind had achieved during the period of ancient civilization. His writings are a real encyclopedia of contemporary science.

Exam abstract

"Astronomy

Ancient Greece"

Performed

11th grade student

Perestoronina Margarita

Teacher

Zhbannikova Tatyana Vladimirovna

Plan
I Introduction.

II Astronomy of the ancient Greeks.

1. On the way to truth, through knowledge.

2. Aristotle and the geocentric system of the world.

3. The same Pythagoras.

4. The first heliocentrist.

5. Works of the Alexandrian astronomers

6. Aristarchus: a perfect method (his true works and successes; the reasoning of an outstanding scientist; a great theory is a failure as a consequence);

7. "Phaenomena" Euclid and the basic elements of the celestial sphere.

9. Calendar and stars of ancient Greece.

III Conclusion: the role of astronomers in ancient Greece.

Introduction

... Aristarchus of Samos in his "Proposals" -

admitted that the stars, the sun do not change

its position in space that the earth

moves in a circle around the sun,

located in the center of her path, and that

center of the sphere of fixed stars

coincides with the center of the sun.

Archimedes. Psamit.

Assessing the path made by mankind in search of truth about the Earth, we voluntarily or involuntarily turn to the ancient Greeks. Much originated with them, but through them a lot has come down to us from other peoples. This is how history decreed: the scientific ideas and territorial discoveries of the Egyptians, Sumerians and other ancient Eastern peoples were often preserved only in the memory of the Greeks, and from them they became known to subsequent generations. A striking example of this is the detailed news about the Phoenicians, who inhabited a narrow strip of the eastern coast of the Mediterranean Sea and in the 2nd-1st millennium BC. e. who discovered Europe and the coastal regions of Northwest Africa. Strabo, a Roman scholar and Greek by birth, in his seventeen-volume Geography wrote: "Until now, the Hellenes borrow a lot from the Egyptian priests and Chaldeans." But Strabo was skeptical of his predecessors, including the Egyptians.

The heyday of Greek civilization falls on the period between the VI century BC. and the middle of the 2nd century BC. e. Chronologically, it almost coincides with the time of the existence of classical Greece and Hellenism. This time, taking into account several centuries, when the Roman Empire rose, prospered and perished, is called antique. Its initial boundary is considered to be the 7th-2nd centuries BC, when the policies-Greek city-states were rapidly developing. This form of government became a hallmark of the Greek world.

The development of knowledge among the Greeks has no analogues in the history of that time. The scale of the comprehension of sciences can be imagined at least by the fact that in less than three centuries (!) Greek mathematics has gone its way - from Pythagoras to Euclid, Greek astronomy - from Thales to Euclid, Greek natural science - from Anaximander to Aristotle and Theophrastus, Greek geography - from Hekkatheus of Miletus to Eratosthenes and Hipparchus, etc.

The discovery of new lands, land or sea voyages, military campaigns, overpopulation in fertile areas - all this was often mythologized. In the poems, with the artistic skill inherent in the Greeks, the mythical side by side with the real. They set out scientific knowledge, information about the nature of things, as well as geographical data. However, the latter are sometimes difficult to identify with today's ideas. And, nevertheless, they are an indicator of the broad views of the Greeks on the ecumene.

The Greeks paid great attention specifically to the geographical knowledge of the Earth. Even during military campaigns, they did not leave the desire to write down everything that they saw in the conquered countries. In the troops of Alexander the Great, even special pedometers were allocated, which counted the distances traveled, compiled a description of the routes of movement and put them on the map. Based on the data they received, Dikearchus, a student of the famous Aristotle, compiled a detailed map of the ecumene of that time, according to him.

... The simplest cartographic drawings were known even in primitive society, long before the advent of writing. This can be judged by rock paintings. The first cards appeared in ancient Egypt. On clay tablets, the contours of individual territories were drawn with the designation of some objects. Not later than 1700 BC. e. The Egyptians made a map of the developed two thousand-kilometer part of the Nile.

The Babylonians, Assyrians and other peoples of the Ancient East were also engaged in mapping the terrain ...

What did the Earth look like? What place did they assign to themselves on it? What were their ideas about the ecumene?

Astronomy of the ancient Greeks

In Greek science, the opinion was firmly established (with various variations, of course) that the Earth is like a flat or convex disk surrounded by an ocean. Many Greek thinkers did not abandon this point of view even when, in the era of Plato and Aristotle, the ideas about the sphericity of the Earth seemed to prevail. Alas, even in those distant times, the progressive idea made its way with great difficulty, demanded sacrifices from its supporters, but, fortunately, then “talent did not seem like heresy”, and “boots did not go in arguments”.

The idea of ​​a disk (drum, or even a cylinder) was very handy in confirming the widely held belief that Hellas was in the middle. It was also quite acceptable for depicting land floating in the ocean.

Within the disk-shaped (and later spherical) Earth, the ecumene stood out. Which in ancient Greek means the whole inhabited earth, the universe. The designation in one word of two seemingly different concepts (for the Greeks then they seemed to be of the same ordinal) is deeply symptomatic.

Little reliable information has been preserved about Pythagoras (VI century BC). It is known that he was born on the island of Samos; probably visited Miletus in his youth, where he studied with Anaximander; may have traveled further afield. Already in adulthood, the philosopher moved to the city of Croton and founded there something like a religious dress - the Pythagorean brotherhood, which extended its influence to many Greek cities in southern Italy. The life of the brotherhood was surrounded by mystery. There were legends about its founder Pythagoras, which, apparently, had some basis: the great scientist was no less a great politician and seer.

The basis of the teachings of Pythagoras was the belief in the transmigration of souls and the harmonious arrangement of the world. He believed that music and mental labor purifies the soul, so the Pythagoreans considered it necessary to improve in the “four arts” - arithmetic, music, geometry and astronomy. Pythagoras himself is the founder of number theory, and the theorem he proved is known today to every schoolchild. And if Anaxagoras and Democritus in their views of the world developed Anaximander's idea of ​​the physical causes of natural phenomena, then Pythagoras shared his conviction in the mathematical harmony of the cosmos.

The Pythagoreans ruled in the Greek cities of Italy for several decades, then they were defeated and moved away from politics. However, much of what Pythagoras breathed into them remained alive and had a huge impact on science. Now it is very difficult to separate the contribution of Pythagoras himself from the achievements of his followers. This applies in particular to astronomy, in which several fundamentally new ideas have been put forward. They can be judged by the meager information that has come down to us about the ideas of the late Pythagoreans and the teachings of philosophers who were influenced by the ideas of Pythagoras.

Aristotle and the first scientific picture of the world

Aristotle was born in the Macedonian city of Stagira in the family of a court physician. At the age of seventeen, he ends up in Athens, where he becomes a student of the Academy founded by the philosopher Plato.

At first, Aristotle was fascinated by Plato's system, but gradually he came to the conclusion that the views of the teacher lead away from the truth. And then Aristotle left the Academy, throwing the famous phrase: "Plato is my friend, but the truth is dearer." Emperor Philip of Macedon invites Aristotle to become the tutor of the heir to the throne. The philosopher agrees and for three years he has been near the future founder of the great empire, Alexander the Great. At the age of sixteen, his disciple led his father's army and, having defeated the Thebans in his first battle of Chaeronea, went on campaigns.

Again, Aristotle moves to Athens, and in one of the districts, called Lyceum, he opens a school. He writes a lot. His writings are so varied that it is difficult to imagine Aristotle as a solitary thinker. Most likely, during these years he acted as the head of a large school, where students worked under his leadership, just as today graduate students develop topics that are offered to them by leaders.

The Greek philosopher paid much attention to questions of the structure of the world. Aristotle was convinced that at the center of the universe, of course, is the Earth.

Aristotle tried to explain everything with reasons that are close to the common sense of the observer. So, observing the Moon, he noticed that in various phases it exactly corresponds to the form that a ball would take, on one side illuminated by the Sun. Equally rigorous and logical was his proof of the sphericity of the Earth. After discussing all the possible reasons for the eclipse of the Moon, Aristotle comes to the conclusion that the shadow on its surface can only belong to the Earth. And since the shadow is round, then the body that casts it must have the same shape. But Aristotle is not limited to them. “Why,” he asks, “when we move north or south, do the constellations change their positions relative to the horizon?” And then he answers: “Because the Earth has a curvature”. Indeed, if the Earth were flat, wherever the observer was, the same constellations would shine above his head. It is quite another thing - on a round Earth. Here, each observer has his own horizon, his own horizon, his own sky... However, recognizing the sphericity of the Earth, Aristotle spoke out categorically against the possibility of its circulation around the Sun. “Be it so,” he reasoned, “it would seem to us that the stars are not motionless on the celestial sphere, but describe circles ...” This was a serious objection, perhaps the most serious, which was eliminated only many, many centuries later, in the 19th century.

Much has been written about Aristotle. The authority of this philosopher is incredibly high. And it is well deserved. Because, despite the rather numerous errors and misconceptions, in his writings Aristotle collected everything that the mind had achieved during the period of ancient civilization. His writings are a real encyclopedia of contemporary science.

According to contemporaries, the great philosopher was distinguished by an unimportant character. The portrait that has come down to us presents us with a small, lean man with an eternally caustic grin on his lips.

He spoke curtly.

In dealing with people, he was cold and arrogant.

But few dared to enter into an argument with him. The witty, angry and mocking speech of Aristotle struck on the spot. He smashed the arguments raised against him deftly, logically and cruelly, which, of course, did not add to his supporters among the vanquished.

After the death of Alexander the Great, the offended finally felt real opportunity get even with the philosopher and accused him of godlessness. Aristotle's fate was sealed. Without waiting for the verdict, Aristotle flees from Athens. “To rid the Athenians of a new crime against philosophy,” he says, alluding to the similar fate of Socrates, who received a cup of poisonous hemlock juice by sentence.

After leaving Athens for Asia Minor, Aristotle soon dies, poisoned during a meal. So says the legend.

According to legend, Aristotle bequeathed his manuscripts to one of his students named Theophrastus.

Upon the death of a philosopher, a real hunt begins for his works. In those days, books were treasures in their own right. The books of Aristotle were valued more than gold. They passed from hand to hand. They were hidden in the cellars. Walled up in cellars to save from the greed of the Pergamon kings. Dampness spoiled their pages. Already under Roman rule, the writings of Aristotle as war booty come to Rome. Here they are sold to amateurs - the rich. Some people try to restore the damaged parts of the manuscripts, to supply them with their own additions, which, of course, does not make the text better.

Why were the works of Aristotle so highly valued? After all, in the books of other Greek philosophers there were more original thoughts. This question is answered by the English philosopher and physicist John Bernal. Here is what he writes: “No one could understand them (the ancient Greek thinkers), except for very well prepared and sophisticated readers. And the works of Aristotle, for all their cumbersomeness, did not require (or did not seem to require) for their understanding anything but common sense ... To verify his observations, there was no need for experiments or instruments, difficult mathematical calculations or mystical intuition were not needed either. to understand any inner meaning ... Aristotle explained that the world is the way everyone knows it, exactly the way they know it.

Time will pass, and the authority of Aristotle will become unconditional. If in a dispute one philosopher, confirming his arguments, refers to his works, this will mean that the arguments are certainly correct. And then the second disputant must find another quote in the writings of the same Aristotle, with the help of which it is possible to refute the first one. ... Only Aristotle against Aristotle. Other arguments against quotations were powerless. Such a method of dispute is called dogmatic, and, of course, there is not an ounce of benefit or truth in it ... But many centuries had to pass before people understood this and rose to fight dead scholasticism and dogmatism. This struggle revived the sciences, revived the art and gave the name of the era - the Renaissance.

First heliocentrist

In ancient times, the question of whether the Earth moves around the Sun was simply blasphemous. Both famous scientists and ordinary people, for whom the picture of the sky did not cause much thought, were sincerely convinced that the Earth is motionless and represents the center of the Universe. However, modern historians can name at least one ancient scientist who challenged the conventional wisdom and tried to develop a theory that the earth moves around the sun.

The life of Aristarchus of Samos (310 - 250 BC) was closely associated with the Library of Alexandria. Information about him is very scarce, and from creative heritage only the book "On the sizes of the Sun and the Moon and the distances to them", written in 265 BC, remained. Only mentions of him by other scientists of the Alexandrian school, and later by the Romans, shed some light on his "blasphemous" scientific research.

Aristarchus wondered how far from the Earth to the celestial bodies, and what are their sizes. Before him, the Pythagoreans tried to answer this question, but they proceeded from arbitrary sentences. So, Philolaus believed that the distances between the planets and the Earth are growing exponentially and each next planet is three times farther from the Earth than the previous one.

Aristarchus went his own way, completely correct from the point of view of modern science. He closely followed the moon and the change of its phases. At the moment of the onset of the first quarter phase, he measured the angle between the Moon, the Earth and the Sun (the LZS angle in Fig.). If this is done accurately enough, then only calculations will remain in the problem. At this moment, the Earth, Moon and Sun form a right triangle, and, as is known from geometry, the sum of the angles in it is 180 degrees. In this case, the second acute angle of the Earth - the Sun - the Moon (the angle of the ESL) is equal to

90˚ - Ð LZS = Ð ZSL

Determination of the distance from the Earth to the Moon and the Sun by the method of Aristarchus.

Aristarchus obtained from his measurements and calculations that this angle is 3º (actually its value is 10') and that the Sun is 19 times farther from the Earth than the Moon (actually 400 times). Here we must forgive the scientist for a significant mistake, because the method was absolutely correct, but the inaccuracies in measuring the angle turned out to be great. It was difficult to accurately capture the moment of the first quarter, and the ancient measuring instruments themselves were far from perfect.

But this was only the first success of the remarkable astronomer Aristarchus of Samos. It fell to him to observe a total solar eclipse when the disk of the Moon covered the disk of the Sun, i.e., the apparent sizes of both bodies in the sky were the same. Aristarchus rummaged through the old archives, where he found a lot of additional information about eclipses. It turned out that in some cases solar eclipses were annular, that is, a small luminous rim from the Sun remained around the disk of the Moon (the presence of total and annular eclipses is due to the fact that the Moon's orbit around the Earth is an ellipse). But if the visible disks of the Sun and the Moon in the sky are almost the same, Aristarchus reasoned, and the Sun is 19 times farther from the Earth than the Moon, then its diameter should be 19 times larger. What is the relationship between the diameters of the Sun and the Earth? According to many data on lunar eclipses, Aristarchus established that the lunar diameter is approximately one third of the earth's and, therefore, the latter should be 6.5 times less than the solar one. At the same time, the volume of the Sun should be 300 times the volume of the Earth. All these arguments distinguish Aristarchus of Samos as an outstanding scientist of his time.

body" of Aristotle. But can the huge Sun revolve around the small Earth? Or even more huge All -

lazy? And Aristotle said no, he can't. The sun is the center of the universe, the earth and planets revolve around it, and only the moon revolves around the earth.

Why does day turn into night on Earth? And Aristarchus gave the correct answer to this question - the Earth not only revolves around the Sun, but also rotates around its axis.

And he answered one more question perfectly. Let us give an example with a moving train, when external objects close to the passenger run past the window faster than distant ones. The earth moves around the sun, but why does the star pattern stay the same? Aristotle replied: "Because the stars are unimaginably far from the small Earth." The volume of the sphere of fixed stars is so many times greater than the volume of a sphere with a radius of the Earth - the Sun, how many times the volume of the latter is greater than the volume of the globe.

This new theory was called heliocentric, and its essence was that the motionless Sun was placed at the center of the universe and the sphere of stars was also considered motionless. Archimedes in his book “Psamit”, an excerpt from which is given as an epigraph to this essay, accurately conveyed everything that Aristarchus proposed, but he himself preferred to “return” the Earth to its old place again. Other scholars have completely rejected the theory of Aristarchus as implausible, and the idealist philosopher Cleanthes simply accused him of blasphemy. The ideas of the great astronomer did not find a basis for further development at that time, they determined the development of science for about one and a half thousand years and then revived only in the works of the Polish scientist Nicolaus Copernicus.

The ancient Greeks believed that poetry, music, painting and science were patronized by nine muses, who were the daughters of Mnemosyne and Zeus. So, the muse Urania patronized astronomy and was depicted with a crown of stars and a scroll in her hands. Clio was considered the muse of history, Terpsichore was the muse of dances, Melpomene was the muse of tragedies, etc. The Muses were the companions of the god Apollo, and their temple was called the museumon - the house of the Muses. Such temples were built both in the metropolis and in the colonies, but the Alexandrian Museum became an outstanding academy of sciences and arts of the ancient world.

Ptolemy Lag, being a persistent man and wanting to leave a memory of himself in history, not only strengthened the state, but also turned the capital into a trading center for the entire Mediterranean, and the Museum into a scientific center of the Hellenistic era. The huge building housed a library, a higher school, an astronomical observatory, a medical-anatomical school and a number of scientific departments. The museum was a public institution, and its expenses provided -

fell under the corresponding budget item. Ptolemy, like Ashurbanipal in Babylon in his time, sent scribes throughout the country to collect cultural treasures. In addition, each ship entering the port of Alexandria was obliged to transfer literary works on board to the library. Scientists from other countries considered it an honor to work in the scientific institutions of the Museum and leave their work here. For four centuries, the astronomers Aristarchus of Samos and Hipparchus, the physicist and engineer Heron, the mathematicians Euclid and Archimedes, the doctor Herophilus, the astronomer and geographer Claudius Ptolemy and Eratosthenes worked in Alexandria, who was equally successful in mathematics, geography, astronomy, and philosophy.

But the latter was rather an exception, since an important feature of the Hellenic era was the "differentiation" of scientific activity. Here it is curious to note that such a separation of individual sciences, and in astronomy and specialization in certain areas, occurred in ancient China much earlier.

Another feature of Hellenic science was that it again turned to nature, i.e. she began to "extract" the facts herself. The Encyclopedists of Ancient Hellas relied on information obtained by the Egyptians and Babylonians, and therefore were engaged only in the search for the causes that cause certain phenomena. The science of Democritus, Anaxagoras, Plato and Aristotle was even more speculative, although their theories can be regarded as the first serious attempts of mankind to understand the structure of nature and the entire Universe. The Alexandrian astronomers closely followed the movements of the Moon, the planets, the Sun, and the stars. The complexity of planetary movements and the richness of the stellar world forced them to look for starting points from which systematic research could begin.

"Phaenomena" Euclid and the basic elements of the celestial sphere

As mentioned above, the Alexandrian astronomers tried to determine the "starting" points for further systematic research. In this regard, special merit belongs to the mathematician Euclid (III century BC), who in his book "Phaenomena" first introduced concepts into astronomy that had not been used in it until then. So, he gave definitions of the horizon - a great circle, which is the intersection of a plane perpendicular to the plumb line at the point of observation, with the celestial sphere, as well as the celestial equator - a circle obtained by intersecting the plane of the earth's equator with this sphere.

In addition, he determined the zenith - the point of the celestial sphere above the observer's head ("zenith" is an Arabic word) - and the point opposite to the zenith point - the nadir.

And Euclid spoke about one more circle. This is heaven -

ny meridian - a large circle passing through the Pole of the world and the zenith. It is formed at the intersection with the celestial sphere of a plane passing through the axis of the world (axis of rotation) and a plumb line (ie, a plane perpendicular to the plane of the earth's equator). Relate -

Regarding the value of the meridian, Euclid said that when the Sun crosses the meridian, noon comes in this place and the shadows of objects are the shortest. To the east of this place, noon on the globe has already passed, and to the west it has not yet arrived. As we remember, the principle of measuring the shadow of a gnomon on Earth for many centuries underlay the design of sundials.

The brightest "star" of the Alexandrian sky.

Earlier we have already got acquainted with the results of the activities of many astronomers, both famous and those

whose names have sunk into oblivion. Even thirty centuries before the new era, Heliopolis astronomers in Egypt established the length of the year with amazing accuracy. Curly-bearded priests - astronomers, who observed the sky from the tops of the Babylonian ziggurats, were able to draw the path of the Sun among the constellations - the ecliptic, as well as the celestial paths of the Moon and stars. In distant and mysterious China, the inclination of the ecliptic to the celestial equator was measured with high accuracy.

Ancient Greek philosophers sowed seeds of doubt about the divine origin of the world. Under Aristarchus, Euclid and Eratosthenes, astronomy, which until then had given away most of the astrology, began to systematize its research, standing on the firm ground of true knowledge.

And yet what Hipparchus did about the field of astronomy far exceeds the achievements of both his predecessors and scientists of a later time. With good reason, Hipparchus is called the father of scientific astronomy. He was extremely punctual in his research, repeatedly checking the conclusions with new observations and striving to discover the essence of the phenomena occurring in the Universe.

The history of science does not know where and when Hipparchus was born; it is only known that the most fruitful period of his life falls on the time between 160 and 125 years. BC e.

He spent most of his research at the Alexandria Observatory, as well as at his own observatory built on the island of Samos.

Even before the Hipparchatheory of the celestial spheres, Eudoxus and Aristotle were rethought, in particular, by the great Alexandrian mathematician Apollonius of Perga (3rd century BC), but the Earth still remained at the center of the orbits of all celestial bodies.

Hipparchus continued the development of the theory of circular orbits begun by Apollonius, but made significant additions to it, based on long-term observations. Earlier, Calippus, a student of Eudoxus, discovered that the seasons were not of the same length. Hipparchus checked this statement and clarified that astronomical spring lasts 94 and ½ days, summer - 94 and ½ days, autumn - 88 days and, finally, winter lasts 90 days. Thus, the time interval between the spring and autumn equinoxes (including summer) is 187 days, and the interval from the autumn equinox to the spring equinox (including winter) is 88 + 90 = 178 days. Consequently, the Sun moves unevenly along the ecliptic - slower in summer and faster in winter. Another explanation of the reason for the difference is also possible, if we assume that the orbit is not a circle, but an “elongated” closed curve (Appolonius of Perga called it an ellipse). However, to accept the non-uniformity of the Sun's motion and the difference of the orbit from a circular one meant to turn upside down all ideas that had been established since the time of Plato. Therefore, Hipparchus introduced a system of eccentric circles, assuming that the Sun revolves around the Earth in a circular orbit, but the Earth itself is not at its center. The unevenness in this case is only apparent, because if the Sun is closer, then the impression of its faster movement arises, and vice versa.

However, for Hipparchus, the direct and backward movements of the planets remained a mystery, i.e. the origin of the loops that the planets described in the sky. Changes in the apparent brightness of the planets (especially for Mars and Venus) testified that they also move along eccentric orbits, now approaching the Earth, now moving away from it and changing brightness accordingly. But what is the reason for the forward and backward movements? Hipparchus came to the conclusion that the placement of the Earth away from the center of the orbits of the planets is not enough to explain this riddle. Three centuries later, the last of the great Alexandrians, Claudius Ptolemy, noted that Hipparchus abandoned the search for this direction and limited himself to systematizing his own observations and those of his predecessors. It is curious that at the time of Hipparchus, the concept of an epicycle already existed in astronomy, the introduction of which is attributed to Apollonius of Perga. But one way or another, Hipparchus did not engage in the theory of planetary motion.

But he successfully modified the method of Aristarchus, which makes it possible to determine the distance to the Moon and the Sun. The spatial arrangement of the Sun, Earth and Moon during a lunar eclipse when observations were made.

Hipparchus also became famous for his work in the field of stellar research. He, like his predecessors, believed that the sphere of fixed stars really exists, i.e. objects located on it are at the same distance from the Earth. But why then are some of them brighter than others? Therefore, Hipparchus believed that their true sizes are not the same - the larger the star, the brighter it is. He divided the brightness range into six magnitudes, from the first - for the brightest stars to the sixth - for the faintest, still visible to the naked eye (naturally, there were no telescopes then). In the modern scale of stellar magnitudes, a difference of one magnitude corresponds to a difference in radiation intensity of 2.5 times.

In 134 BC, a new star shone in the constellation Scorpio (now it is established that new stars are binary systems in which an explosion of matter occurs on the surface of one of the components, accompanied by a rapid increase in the object's blackness, followed by attenuation). Earlier on there was nothing in this place, and therefore Hipparchus came to the conclusion that it was necessary to create an accurate star catalog. With extraordinary care, the great astronomer measured the ecliptic coordinates of about 1000 stars, and also estimated their magnitudes on his scale.

While doing this work, he decided to test the opinion that the stars are fixed. More precisely, descendants should have done it. Hipparchus compiled a list of stars located in one straight line, in the hope that future generations of astronomers would check whether this line remained straight.

While compiling the catalog, Hipparchus made a remarkable discovery. He compared his results with the coordinates of a number of stars measured before him by Aristylus and Timocharis (contemporaries of Aristarchus of Samos), and found that the ecliptic longitudes of objects increased by about 2º over 150 years. At the same time, the ecliptic latitudes did not change. It became clear that the reason was not in the proper motions of the stars, otherwise both coordinates would have changed, but in the movement of the vernal equinox point, from which the ecliptic longitude is measured, and in the direction opposite to the movement of the Sun along the ecliptic. As you know, the vernal equinox is the intersection of the ecliptic with the celestial equator. Since the ecliptic latitude does not change with time, Hipparchus concluded that the reason for the shift of this point is the movement of the equator.

Thus, we have the right to be surprised at the extraordinary consistency and rigor in the scientific research of Hipparchus, as well as their high accuracy. The French scientist Delambre, a well-known researcher of ancient astronomy, described his activities as follows: “When you take a look at all the discoveries and improvements of Hipparchus, reflect on the number of his works and the many calculations given there, willy-nilly you will attribute him to the most prominent people of antiquity and, moreover, call the greatest among them. Everything he has achieved belongs to the field of science, where geometric knowledge is required, combined with an understanding of the essence of phenomena that can be observed only if tools are carefully made ... ”

Calendar and stars

In ancient Greece, as in the countries of the East, the lunar-solar calendar was used as a religious and civil one. In it, the beginning of each calendar month was to be located as close as possible to the new moon, and the average duration of the calendar year should, if possible, correspond to the time interval between the spring equinoxes (“tropical year”, as it is now called). At the same time, months of 30 and 29 days alternated. But 12 lunar months are about a third of a month shorter than a year. Therefore, in order to fulfill the second requirement, from time to time it was necessary to resort to intercalations - to add an additional, thirteenth, month in some years.

Insertions were made irregularly by the government of each policy - the city-state. For this, special persons were appointed to monitor the magnitude of the lag of the calendar year from the solar year. In Greece, divided into small states, calendars had a local meaning - there were about 400 names of months in the Greek world. The mathematician and musicologist Aristoxenus (354-300 BC) wrote about the calendar disorder: “The tenth day of the month among the Corinthians is the fifth day the Athenian has the eighth for someone else”

Simple and precise, the 19-year cycle, used as far back as Babylon, was proposed in 433 BC. Athenian astronomer Meton. This cycle included the insertion of seven additional months in 19 years; its error did not exceed two hours in one cycle.

Farmers associated with seasonal work, since ancient times, also used the stellar calendar, which did not depend on the complex movements of the Sun and Moon. Hesiod in the poem “Works and Days”, indicating to his brother Persian the time of agricultural work, marks them not according to the lunisolar calendar, but according to the stars:

Only in the east will they begin to rise

Atlantis Pleiades,

Hurry up, and they will begin

Come in, accept the sowing ...

Sirius is high in the sky

Got up with Orion

Dawn pink-fingered is already beginning

see Arthur,

Cut, O Persian, and take home

Grape bunches…

Thus, a good knowledge of the starry sky, which few people in the modern world can boast of, was necessary for the ancient Greeks and, obviously, widespread. Apparently, this science was taught to children in families from an early age. The lunisolar calendar was also used in Rome. But even more “calendar arbitrariness” reigned here. The length and beginning of the year depended on the pontiffs (from the Latin Pontifices), Roman priests, who often used their right for selfish purposes. Such a situation could not satisfy the huge empire into which the Roman state was rapidly turning. In 46 BC Julius Caesar (100-44 BC), who acted not only as the head of state, but also as the high priest, carried out a calendar reform. The new calendar, on his behalf, was developed by the Alexandrian mathematician and astronomer Sosigen, a Greek by origin. He took the Egyptian, purely solar, calendar as a basis. The refusal to take into account the lunar phases made it possible to make the calendar quite simple and accurate. This calendar, called the Julian, was used in the Christian world until the introduction of the updated Gregorian calendar in the Catholic countries in the 16th century.

The Julian calendar began in 45 BC. The beginning of the year was moved to January 1 (earlier the first month was March). In gratitude for the introduction of the calendar, the Senate decided to rename the month quintilis (fifth), in which Caesar was born, into Julius - our July. In 8 BC the honor of the next emperor, Octivian Augustus, the month sextilis (sixth), was renamed August. princeps?”

The new calendar turned out to be purely civil, religious holidays, by virtue of tradition, were still celebrated in accordance with the phases of the moon. And at present, the Easter holiday is coordinated with the lunar calendar, and the cycle proposed by Meton is used to calculate its date.

Conclusion

In the distant Middle Ages, Bernard of Chartres spoke golden words to his students: “We are like dwarfs sitting on the shoulders of giants; we see more and farther than they, not because we have better eyesight, and not because we are higher than them, but because they raised us and increased our stature with their greatness. Astronomers of any era have always leaned on the shoulders of previous giants.

Ancient astronomy occupies a special place in the history of science. It was in ancient Greece that the foundations of modern scientific thinking were laid. For seven and a half centuries, from Thales and Anaximander, who took the first steps in comprehending the Universe, to Claudius Ptolemy, who created the mathematical theory of the movement of the stars, ancient scientists have come a long way, on which they had no predecessors. Astronomers of antiquity used data obtained long before them in Babylon. However, for their processing, they created completely new mathematical methods, which were adopted by medieval Arab and later European astronomers.

In 1922, the International Astronomical Congress approved 88 international names for the constellations, thereby perpetuating the memory of the ancient Greek myths, after which the constellations were named: Perseus, Andromeda, Hercules, etc. (about 50 constellations). The meaning of ancient Greek science is emphasized by the words: planet, comet, galaxy and the very word Astronomy.

List of used literature

1. "Encyclopedia for children." Astronomy. (M. Aksenova, V. Tsvetkov, A. Zasov, 1997)

2. "Stargazers of antiquity." (N. Nikolov, V. Kharalampiev, 1991)

3. "Discovery of the Universe - past, present, future." (A. Potupa, 1991)

4. "Horizons of the Ecumene". (Yu. Gladky, Al. Grigoriev, V. Yagya, 1990)

5. Astronomy, grade 11. (E. Levitan, 1994)

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