There are many different coordinate systems, all of which are used to determine the position of points on earth's surface. This includes mainly geographical coordinates, flat rectangular and polar coordinates. In general, coordinates are usually called angular and linear quantities that define points on any surface or in space.

Geographical coordinates- these are angular values - latitude and longitude, which determine the position of a point on the globe. Geographic latitude is the angle formed by the equatorial plane and a plumb line at a given point on the earth's surface. This angle value shows how far a particular point on the globe is north or south of the equator.

If a point is located in the Northern Hemisphere, then its geographic latitude will be called northern, and if in the Southern Hemisphere - southern latitude. The latitude of points located on the equator is zero degrees, and at the poles (North and South) - 90 degrees.

Geographic longitude is also an angle, but formed by the plane of the meridian, taken as the initial (zero), and the plane of the meridian passing through a given point. For uniformity of definition, we agreed to consider the prime meridian to be the meridian passing through the astronomical observatory in Greenwich (near London) and call it Greenwich.

All points located to the east of it will have eastern longitude (up to the meridian 180 degrees), and to the west of the initial one will have western longitude. The figure below shows how to determine the position of point A on the earth's surface if its geographic coordinates (latitude and longitude) are known.

Note that the difference in longitude of two points on Earth shows not only their relative position in relation to the prime meridian, but also the difference in these points at the same moment. The fact is that every 15 degrees (24th part of the circle) in longitude is equal to one hour of time. Based on this, it is possible to determine the time difference at these two points using geographic longitude.

For example.

Moscow has a longitude of 37°37′ (east), and Khabarovsk -135°05′, that is, lies east of 97°28′. What time do these cities have at the same moment? Simple calculations show that if it is 13 hours in Moscow, then in Khabarovsk it is 19 hours 30 minutes.

The figure below shows the design of the frame of a sheet of any card. As can be seen from the figure, in the corners of this map the longitude of the meridians and the latitude of the parallels that form the frame of the sheet of this map are written.

On all sides the frame has scales divided into minutes. For both latitude and longitude. Moreover, each minute is divided into 6 equal sections by dots, which correspond to 10 seconds of longitude or latitude.

Thus, in order to determine the latitude of any point M on the map, it is necessary to draw a line through this point, parallel to the lower or upper frame of the map, and read the corresponding degrees, minutes, seconds on the right or left along the latitude scale. In our example, point M has a latitude of 45°31’30”.

Similarly, drawing a vertical line through point M parallel to the lateral (closest to this point) meridian of the border of a given map sheet, we read the longitude (eastern) equal to 43°31’18”.

Drawing a point on a topographic map at specified geographic coordinates.

Drawing a point on a map at specified geographic coordinates is done in the reverse order. First, the indicated geographic coordinates are found on the scales, and then parallel and perpendicular lines are drawn through them. Their intersection will show a point with the given geographic coordinates.

Based on materials from the book “Map and Compass are My Friends.”
Klimenko A.I.

Globes and geographic maps have a coordinate system. With its help, you can plot any object on a globe or map, as well as find it on the earth's surface. What is this system, and how to determine the coordinates of any object on the surface of the Earth with its participation? We will try to talk about this in this article.

Geographic latitude and longitude

Longitude and latitude are geographical concepts that are measured in angular units (degrees). They serve to indicate the position of any point (object) on the earth's surface.

Geographic latitude is the angle between a plumb line at a particular point and the plane of the equator (zero parallel). Latitude in the Southern Hemisphere is called southern, and in the Northern Hemisphere it is called northern. Can vary from 0∗ to 90∗.

Geographic longitude is the angle made by the meridian plane at a certain point to the plane of the prime meridian. If the longitude is counted east from the prime Greenwich meridian, then it will be east longitude, and if it is to the west, then it will be west longitude. Longitude values can range from 0∗ to 180∗. Most often, on globes and maps, meridians (longitude) are indicated when they intersect with the equator.

How to determine your coordinates

When a person finds himself in an emergency situation, he must, first of all, be well oriented in the area. In some cases, it is necessary to have certain skills in determining the geographic coordinates of your location, for example, in order to convey them to rescuers. There are several ways to do this using improvised methods. We present the simplest of them.

Determining longitude by gnomon

If you go traveling, it is best to set your watch to Greenwich time:

It is necessary to determine when it will be noon GMT in a given area.
Stick a stick (gnomon) to determine the shortest solar shadow at noon.
Find the minimum shadow cast by the gnomon. This time will be local noon. In addition, this shadow will point strictly north at this time.
Using this time, calculate the longitude of the place where you are.

Calculations are made based on the following:

since the Earth makes a complete revolution in 24 hours, therefore, it will travel 15 ∗ (degrees) in 1 hour;
4 minutes of time will be equal to 1 geographical degree;
1 second of longitude will be equal to 4 seconds of time;
if noon occurs before 12 o'clock GMT, this means that you are in the Eastern Hemisphere;
If you spot the shortest shadow after 12 o'clock GMT, then you are in the Western Hemisphere.

An example of the simplest calculation of longitude: the shortest shadow was cast by the gnomon at 11 hours 36 minutes, that is, noon came 24 minutes earlier than at Greenwich. Based on the fact that 4 minutes of time are equal to 1 ∗ longitude, we calculate - 24 minutes / 4 minutes = 6 ∗. This means that you are in the Eastern Hemisphere at 6 ∗ longitude.

How to determine geographic latitude

The determination is made using a protractor and a plumb line. To do this, a protractor is made from 2 rectangular strips and fastened in the form of a compass so that the angle between them can be changed.

A thread with a load is fixed in the central part of the protractor and plays the role of a plumb line.
With its base, the protractor is aimed at the North Star.
90 ∗ is subtracted from the angle between the plumb line of the protractor and its base. The result is the angle between the horizon and the North Star. Since this star is only 1 ∗ deviated from the axis of the world pole, the resulting angle will be equal to the latitude of the place where you are given time you are.

How to determine geographic coordinates

The simplest way to determine geographic coordinates, which does not require any calculations, is this:

Google maps opens.
Find the exact place there;
- the map is moved with the mouse, moved away and zoomed in using its wheel
- find locality by name using search.
Right-click on the desired location. Select the required item from the menu that opens. In this case, “What is here?” Geographic coordinates will appear in the search line at the top of the window. For example: Sochi - 43.596306, 39.7229. They mean geographic latitude and the longitude of the center of this city. This way you can determine the coordinates of your street or house.

Using the same coordinates you can see the place on the map. You just can’t swap these numbers. If you put longitude first and latitude second, you risk ending up in a different place. For example, instead of Moscow you will end up in Turkmenistan.

How to determine coordinates on a map

To determine the geographic latitude of an object, you need to find the closest parallel to it from the equator. For example, Moscow is located between the 50th and 60th parallels. The closest parallel from the equator is the 50th. To this figure is added the number of degrees of the meridian arc, which is calculated from the 50th parallel to the desired object. This number is 6. Therefore, 50 + 6 = 56. Moscow lies on the 56th parallel.

For determining geographic longitude the object is found on the meridian where it is located. For example, St. Petersburg lies east of Greenwich. Meridian, this one is 30 ∗ away from the prime meridian. This means that the city of St. Petersburg is located in the Eastern Hemisphere at a longitude of 30 ∗.

How to determine the coordinates of the geographic longitude of the desired object if it is located between two meridians? At the very beginning, the longitude of the meridian that is located closer to Greenwich is determined. Then to this value you need to add the number of degrees that is on the parallel arc the distance between the object and the meridian closest to Greenwich.

Example, Moscow is located east of the 30 ∗ meridian. Between it and Moscow the arc of parallel is 8 ∗. This means that Moscow has an eastern longitude and it is equal to 38 ∗ (E).

How to determine your coordinates on topographic maps? Geodetic and astronomical coordinates of the same objects differ on average by 70 m. Parallels and meridians on topographic maps are the inner frames of the sheets. Their latitude and longitude are written in the corner of each sheet. Western Hemisphere map sheets are marked "West of Greenwich" in the northwest corner of the frame. Maps of the Eastern Hemisphere will accordingly be marked “East of Greenwich.”

Coordinates are called angular and linear quantities (numbers) that determine the position of a point on any surface or in space.

In topography, coordinate systems are used that make it possible to most simply and unambiguously determine the position of points on the earth's surface, both from the results of direct measurements on the ground and using maps. Such systems include geographic, flat rectangular, polar and bipolar coordinates.

Geographical coordinates(Fig. 1) – angular values: latitude (j) and longitude (L), which determine the position of an object on the earth’s surface relative to the origin of coordinates – the point of intersection of the prime (Greenwich) meridian with the equator. On a map, the geographic grid is indicated by a scale on all sides of the map frame. Western and east side the frames are meridians, and the north and south are parallels. In the corners of the map sheet, the geographical coordinates of the intersection points of the sides of the frame are written.

Rice. 1. System of geographical coordinates on the earth's surface

In the geographic coordinate system, the position of any point on the earth's surface relative to the origin of coordinates is determined in angular measure. In our country and in most other countries, the point of intersection of the prime (Greenwich) meridian with the equator is taken as the beginning. Being thus uniform for our entire planet, the system of geographic coordinates is convenient for solving problems of determining the relative position of objects located at significant distances from each other. Therefore, in military affairs, this system is used mainly for conducting calculations related to the use of long-range combat weapons, for example, ballistic missiles, aviation, etc.

Plane rectangular coordinates(Fig. 2) - linear quantities that determine the position of an object on a plane relative to the accepted origin of coordinates - the intersection of two mutually perpendicular lines (coordinate axes X and Y).

In topography, each 6-degree zone has its own system of rectangular coordinates. The X axis is the axial meridian of the zone, the Y axis is the equator, and the point of intersection of the axial meridian with the equator is the origin of coordinates.

Rice. 2. System of flat rectangular coordinates on maps

The plane rectangular coordinate system is zonal; it is established for each six-degree zone into which the Earth’s surface is divided when depicting it on maps in the Gaussian projection, and is intended to indicate the position of images of points of the earth’s surface on a plane (map) in this projection.

The origin of coordinates in a zone is the point of intersection of the axial meridian with the equator, relative to which the position of all other points in the zone is determined in a linear measure. The origin of the zone and its coordinate axes occupy a strictly defined position on the earth's surface. Therefore, the system of flat rectangular coordinates of each zone is connected both with the coordinate systems of all other zones, and with the system of geographical coordinates.

The use of linear quantities to determine the position of points makes the system of flat rectangular coordinates very convenient for carrying out calculations both when working on the ground and on a map. Therefore, this system is most widely used among the troops. Rectangular coordinates indicate the position of terrain points, their battle formations and targets, and with their help determine the relative position of objects within one coordinate zone or in adjacent areas of two zones.

Polar and bipolar coordinate systems are local systems. In military practice, they are used to determine the position of some points relative to others in relatively small areas of the terrain, for example, when designating targets, marking landmarks and targets, drawing up terrain diagrams, etc. These systems can be associated with systems of rectangular and geographic coordinates.

2. Determining geographic coordinates and plotting objects on a map using known coordinates

The geographic coordinates of a point located on the map are determined from the nearest parallel and meridian, the latitude and longitude of which are known.

The topographic map frame is divided into minutes, which are separated by dots into divisions of 10 seconds each. Latitudes are indicated on the sides of the frame, and longitudes are indicated on the northern and southern sides.

Rice. 3. Determining the geographic coordinates of a point on the map (point A) and plotting the point on the map according to geographic coordinates (point B)

Using the minute frame of the map you can:

1 . Determine the geographic coordinates of any point on the map.

For example, the coordinates of point A (Fig. 3). To do this, you need to use a measuring compass to measure the shortest distance from point A to the southern frame of the map, then attach the meter to the western frame and determine the number of minutes and seconds in the measured segment, add the resulting (measured) value of minutes and seconds (0"27") with the latitude of the southwest corner of the frame - 54°30".

Latitude points on the map will be equal to: 54°30"+0"27" = 54°30"27".

Longitude is defined similarly.

Using a measuring compass, measure the shortest distance from point A to western frame cards, apply a compass to the southern frame, determine the number of minutes and seconds in the measured segment (2"35"), add the resulting (measured) value to the longitude of the southwestern corner of the frame - 45°00".

Longitude points on the map will be equal to: 45°00"+2"35" = 45°02"35"

2. Plot any point on the map according to the given geographic coordinates.

For example, point B latitude: 54°31 "08", longitude 45°01 "41".

To plot a point in longitude on a map, it is necessary to draw the true meridian through this point, for which you connect the same number of minutes along the northern and southern frames; To plot a point in latitude on a map, it is necessary to draw a parallel through this point, for which you connect the same number of minutes along the western and eastern frames. The intersection of two lines will determine the location of point B.

3. Rectangular coordinate grid on topographic maps and its digitization. Additional grid at the junction of coordinate zones

The coordinate grid on the map is a grid of squares formed by lines parallel to the coordinate axes of the zone. Grid lines are drawn through an integer number of kilometers. Therefore, the coordinate grid is also called the kilometer grid, and its lines are kilometer.

On a 1:25000 map, the lines forming the coordinate grid are drawn through 4 cm, that is, through 1 km on the ground, and on maps 1:50000-1:200000 through 2 cm (1.2 and 4 km on the ground, respectively). On a 1:500000 map, only the outputs of the coordinate grid lines are plotted on the inner frame of each sheet every 2 cm (10 km on the ground). If necessary, coordinate lines can be drawn on the map along these outputs.

On topographic maps, the values of the abscissa and ordinate of coordinate lines (Fig. 2) are signed at the exits of the lines outside the inner frame of the sheet and in nine places on each sheet of the map. The full values of the abscissa and ordinate in kilometers are written near the coordinate lines closest to the corners of the map frame and near the intersection of the coordinate lines closest to the northwestern corner. The remaining coordinate lines are abbreviated with two numbers (tens and units of kilometers). The labels near the horizontal grid lines correspond to the distances from the ordinate axis in kilometers.

Labels near the vertical lines indicate the zone number (one or two first digits) and the distance in kilometers (always three digits) from the origin, conventionally moved west of the zone’s axial meridian by 500 km. For example, the signature 6740 means: 6 - zone number, 740 - distance from the conventional origin in kilometers.

On the outer frame there are outputs of coordinate lines ( additional mesh) coordinate system of the adjacent zone.

4. Determination of rectangular coordinates of points. Drawing points on a map by their coordinates

Using a coordinate grid using a compass (ruler), you can:

1. Determine the rectangular coordinates of a point on the map.

For example, points B (Fig. 2).

To do this you need:

write down X - digitization of the bottom kilometer line of the square in which point B is located, i.e. 6657 km;
measure the perpendicular distance from the bottom kilometer line of the square to point B and, using the linear scale of the map, determine the size of this segment in meters;
add the measured value of 575 m with the digitization value of the lower kilometer line of the square: X=6657000+575=6657575 m.

The Y ordinate is determined in the same way:

write down the Y value - digitization of the left vertical line of the square, i.e. 7363;
measure the perpendicular distance from this line to point B, i.e. 335 m;
add the measured distance to the Y digitization value of the left vertical line of the square: Y=7363000+335=7363335 m.

2. Place the target on the map at the given coordinates.

For example, point G at coordinates: X=6658725 Y=7362360.

To do this you need:

find the square in which point G is located according to the value of whole kilometers, i.e. 5862;
set aside from the lower left corner of the square a segment on the map scale equal to the difference between the abscissa of the target and the bottom side of the square - 725 m;
From the obtained point, along the perpendicular to the right, plot a segment equal to the difference between the ordinates of the target and the left side of the square, i.e. 360 m.

Rice. 2. Determining the rectangular coordinates of a point on the map (point B) and plotting the point on the map using rectangular coordinates (point D)

5. Accuracy of determining coordinates on maps of various scales

The accuracy of determining geographic coordinates using 1:25000-1:200000 maps is about 2 and 10"" respectively.

The accuracy of determining the rectangular coordinates of points from a map is limited not only by its scale, but also by the magnitude of errors allowed when shooting or drawing up a map and plotting various points and terrain objects on it

Most accurately (with an error not exceeding 0.2 mm) geodetic points and are plotted on the map. objects that stand out most sharply in the area and are visible from a distance, having the significance of landmarks (individual bell towers, factory chimneys, tower-type buildings). Therefore, the coordinates of such points can be determined with approximately the same accuracy with which they are plotted on the map, i.e. for a map of scale 1:25000 - with an accuracy of 5-7 m, for a map of scale 1:50000 - with an accuracy of 10- 15 m, for a map of scale 1:100000 - with an accuracy of 20-30 m.

The remaining landmarks and contour points are plotted on the map, and, therefore, determined from it with an error of up to 0.5 mm, and points related to contours that are not clearly defined on the ground (for example, the contour of a swamp), with an error of up to 1 mm.

6. Determining the position of objects (points) in polar and bipolar coordinate systems, plotting objects on a map by direction and distance, by two angles or by two distances

System flat polar coordinates(Fig. 3, a) consists of point O - the origin, or poles, and the initial direction of the OR, called polar axis.

Rice. 3. a – polar coordinates; b – bipolar coordinates

The position of point M on the ground or on the map in this system is determined by two coordinates: the position angle θ, which is measured clockwise from the polar axis to the direction to the determined point M (from 0 to 360°), and the distance OM=D.

Depending on the problem being solved, the pole is taken to be an observation post, a firing position, starting point movements, etc., and behind the polar axis - the geographic (true) meridian, the magnetic meridian (the direction of the magnetic compass needle) or the direction to some landmark.

These coordinates can be either two position angles that determine the directions from points A and B to the desired point M, or the distances D1=AM and D2=BM to it. The position angles in this case, as shown in Fig. 1, b, are measured at points A and B or from the direction of the basis (i.e. angle A = BAM and angle B = ABM) or from any other directions passing through points A and B and taken as the initial ones. For example, in the second case, the location of point M is determined by the position angles θ1 and θ2, measured from the direction of the magnetic meridians. System flat bipolar (two-pole) coordinates(Fig. 3, b) consists of two poles A and B and a common axis AB, called the basis or base of the notch. The position of any point M relative to two data on the map (terrain) of points A and B is determined by the coordinates that are measured on the map or on the terrain.

Drawing a detected object on a map

This is one of the most important points in detecting an object. The accuracy of determining its coordinates depends on how accurately the object (target) is plotted on the map.

Having discovered an object (target), you must first accurately determine by various signs what has been detected. Then, without stopping observing the object and without detecting yourself, put the object on the map. There are several ways to plot an object on a map.

Visually: A feature is plotted on the map if it is near a known landmark.

By direction and distance: to do this, you need to orient the map, find the point of your standing on it, indicate on the map the direction to the detected object and draw a line to the object from the point of your standing, then determine the distance to the object by measuring this distance on the map and comparing it with the scale of the map.

Rice. 4. Drawing the target on the map with a straight line from two points.

If it is graphically impossible to solve the problem in this way (the enemy is in the way, poor visibility, etc.), then you need to accurately measure the azimuth to the object, then translate it into a directional angle and draw on the map from the standing point the direction at which to plot the distance to the object.

To obtain a directional angle, you need to add the magnetic declination of a given map to the magnetic azimuth (direction correction).

Straight serif. In this way, an object is placed on a map of 2-3 points from which it can be observed. To do this, from each selected point, the direction to the object is drawn on an oriented map, then the intersection of straight lines determines the location of the object.

7. Methods of target designation on the map: in graphic coordinates, flat rectangular coordinates (full and abbreviated), by kilometer grid squares (up to a whole square, up to 1/4, up to 1/9 square), from a landmark, from a conventional line, in azimuth and target range, in the bipolar coordinate system

The ability to quickly and correctly indicate targets, landmarks and other objects on the ground is important for controlling units and fire in battle or for organizing battle.

Targeting in geographical coordinates used very rarely and only in cases where targets are distant from given point on the map at a considerable distance, expressed in tens or hundreds of kilometers. In this case, geographic coordinates are determined from the map, as described in question No. 2 of this lesson.

The location of the target (object) is indicated by latitude and longitude, for example, height 245.2 (40° 8" 40" N, 65° 31" 00" E). On the eastern (western), northern (southern) sides of the topographic frame, marks of the target position in latitude and longitude are applied with a compass. From these marks, perpendiculars are lowered into the depth of the topographic map sheet until they intersect (commander’s rulers and standard sheets of paper are applied). The point of intersection of the perpendiculars is the position of the target on the map.

For approximate target designation by rectangular coordinates It is enough to indicate on the map the grid square in which the object is located. The square is always indicated by the numbers of the kilometer lines, the intersection of which forms the southwest (lower left) corner. When indicating the square of the map, the following rule is followed: first they call two numbers signed at the horizontal line (on the western side), that is, the “X” coordinate, and then two numbers at the vertical line (the southern side of the sheet), that is, the “Y” coordinate. In this case, “X” and “Y” are not said. For example, enemy tanks were spotted. When transmitting a report by radiotelephone, the square number is pronounced: "eighty eight zero two."

If the position of a point (object) needs to be determined more accurately, then full or abbreviated coordinates are used.

Work with full coordinates. For example, you need to determine the coordinates of a road sign in square 8803 on a map at a scale of 1:50000. First, determine the distance from the bottom horizontal side of the square to the road sign (for example, 600 m on the ground). In the same way, measure the distance from the left vertical side of the square (for example, 500 m). Now, by digitizing kilometer lines, we determine the full coordinates of the object. The horizontal line has the signature 5988 (X), adding the distance from this line to the road sign, we get: X = 5988600. We define the vertical line in the same way and get 2403500. The full coordinates of the road sign are as follows: X=5988600 m, Y=2403500 m.

Abbreviated coordinates respectively will be equal: X=88600 m, Y=03500 m.

If it is necessary to clarify the position of a target in a square, then target designation is used in an alphabetic or digital way inside the square of a kilometer grid.

During target designation literal way inside the square of the kilometer grid, the square is conditionally divided into 4 parts, each part is assigned capital letter Russian alphabet.

Second way - digital way target designation inside the square kilometer grid (target designation by snail ). This method got its name from the arrangement of conventional digital squares inside the square of the kilometer grid. They are arranged as if in a spiral, with the square divided into 9 parts.

When designating targets in these cases, they name the square in which the target is located, and add a letter or number that specifies the position of the target inside the square. For example, height 51.8 (5863-A) or high-voltage support (5762-2) (see Fig. 2).

Target designation from a landmark is the simplest and most common method of target designation. With this method of target designation, the landmark closest to the target is first named, then the angle between the direction to the landmark and the direction to the target in protractor divisions (measured with binoculars) and the distance to the target in meters. For example: “Landmark two, forty to the right, further two hundred, near a separate bush there is a machine gun.”

Target designation from the conditional line usually used in motion on combat vehicles. With this method, two points are selected on the map in the direction of action and connected by a straight line, relative to which target designation will be carried out. This line is denoted by letters, divided into centimeter divisions and numbered starting from zero. This construction is done on the maps of both transmitting and receiving target designation.

Target designation from a conventional line is usually used in movement on combat vehicles. With this method, two points are selected on the map in the direction of action and connected by a straight line (Fig. 5), relative to which target designation will be carried out. This line is denoted by letters, divided into centimeter divisions and numbered starting from zero.

Rice. 5. Target designation from the conditional line

This construction is done on the maps of both transmitting and receiving target designation.

The position of the target relative to the conditional line is determined by two coordinates: a segment from the starting point to the base of the perpendicular lowered from the target location point to the conditional line, and a perpendicular segment from the conditional line to the target.

When designating targets, the conventional name of the line is called, then the number of centimeters and millimeters contained in the first segment, and, finally, the direction (left or right) and the length of the second segment. For example: “Straight AC, five, seven; to the right zero, six - NP.”

Target designation from a conventional line can be given by indicating the direction to the target at an angle from the conventional line and the distance to the target, for example: “Straight AC, right 3-40, one thousand two hundred – machine gun.”

Target designation in azimuth and range to the target. The azimuth of the direction to the target is determined using a compass in degrees, and the distance to it is determined using an observation device or by eye in meters. For example: “Azimuth thirty-five, range six hundred—a tank in a trench.” This method is most often used in areas where there are few landmarks.

8. Problem solving

Determining the coordinates of terrain points (objects) and target designation on the map is practically practiced educational maps at previously prepared points (marked objects).

Each student determines geographic and rectangular coordinates (maps objects according to known coordinates).

Methods of target designation on the map are worked out: in flat rectangular coordinates (full and abbreviated), by squares of a kilometer grid (up to a whole square, up to 1/4, up to 1/9 of a square), from a landmark, along the azimuth and range of the target.

Every place on earth can be identified by a global coordinate system of latitude and longitude. Knowing these parameters, it is easy to find any location on the planet. A coordinate system has been helping people with this for several centuries in a row.

Historical background for the emergence of geographic coordinates

When people began to travel long distances across deserts and seas, they needed a way to fix their position and know in which direction to move so as not to get lost. Before latitude and longitude appeared on maps, the Phoenicians (600 BC) and Polynesians (400 AD) used the starry sky to calculate latitude.

Over the centuries, quite complex devices were developed, such as the quadrant, astrolabe, gnomon and Arabic kamal. All of them were used to measure the height of the sun and stars above the horizon and thereby measure latitude. And if a gnomon is just a vertical stick that casts a shadow from the sun, then the kamal is a very unique device.

It consisted of a rectangular wooden plank measuring 5.1 by 2.5 cm, to which a rope with several equally spaced knots was attached through a hole in the middle.

These instruments were used to determine latitude even after their invention until they invented reliable method determining latitude and longitude on a map.

Navigators for hundreds of years did not have an accurate idea of location due to the lack of a concept of longitude. There was no precise time device in the world, such as a chronometer, so calculating longitude was simply impossible. Not surprisingly, early navigation was problematic and often resulted in shipwrecks.

Without a doubt, the pioneer of revolutionary navigation was Captain James Cook, who traveled the vast Pacific Ocean thanks to the technical genius Henry Thomas Harrison. In 1759, Harrison developed the first navigational clock. By maintaining accurate Greenwich Mean Time, Harrison's clock allowed sailors to determine what time it was at a point and location, after which it became possible to determine longitude from east to west.

Geographic coordinate system

A geographic coordinate system defines two-dimensional coordinates based on the Earth's surface. It has an angular unit, a prime meridian and an equator with zero latitude. The globe is conventionally divided into 180 degrees of latitude and 360 degrees of longitude. Latitude lines are placed parallel to the equator and are horizontal on the map. Lines of longitude connect the North and South Poles and are vertical on the map. As a result of the overlay, geographic coordinates are formed on the map - latitude and longitude, with which you can determine the position on the surface of the Earth.

This geographic grid gives a unique latitude and longitude for every position on Earth. To increase the accuracy of measurements, they are further subdivided into 60 minutes, and each minute into 60 seconds.

The equator is located at right angles to the Earth's axis, approximately midway between the North and South Poles. At an angle of 0 degrees, it is used in the geographic coordinate system as the starting point for calculating latitude and longitude on a map.

Latitude is defined as the angle between the equatorial line of the Earth's center and the location of its center. The North and South Pole have a width angle of 90. To distinguish locations in the Northern Hemisphere from the Southern Hemisphere, the width is additionally provided in the traditional spelling with N for north or S for south.

The Earth is tilted at about 23.4 degrees, so to find the latitude at the summer solstice, you need to add 23.4 degrees to the angle you are measuring.

How to determine latitude and longitude on a map during the winter solstice? To do this, you need to subtract 23.4 degrees from the angle that is being measured. And at any other time, you need to determine the angle, knowing that it changes by 23.4 degrees every six months and, therefore, about 0.13 degrees per day.

In the northern hemisphere, you can calculate the Earth's tilt and therefore latitude by looking at the angle of the North Star. At the North Pole it will be 90 degrees from the horizon, and at the equator it will be directly ahead of the observer, 0 degrees from the horizon.

Important latitudes:

Northern and Southern polar circles, each is located at 66 degrees 34 minutes north and, respectively, south latitude. These latitudes limit the areas around the poles where the sun does not set at the summer solstice, so the midnight sun predominates there. On the winter solstice, the sun does not rise here, and the polar night sets in.
Tropics are located at 23 degrees 26 minutes in northern and southern latitudes. These latitudinal circles mark the solar zenith at the summer solstice of the northern and southern hemispheres.
Equator lies at latitude 0 degrees. The equatorial plane lies approximately in the middle of the Earth's axis between the north and south poles. The equator is the only circle of latitude corresponding to the circumference of the Earth.

Latitude and longitude on a map are important geographic coordinates. Longitude is much more difficult to calculate than latitude. The Earth rotates 360 degrees per day, or 15 degrees per hour, so there is a direct relationship between longitude and the time the sun rises and falls. The Greenwich meridian is designated by 0 degrees longitude. The sun sets an hour earlier every 15 degrees east of this and an hour later every 15 degrees west. If you know the difference between the sunset time of a location and another famous place, you can understand how far east or west it is from it.

Lines of longitude run from north to south. They converge at the poles. And the longitude coordinates are between -180 and +180 degrees. The Greenwich meridian is the datum line of longitude, which measures the east-west direction in a system of geographic coordinates (such as latitude and longitude on a map). In fact, the zero line passes through the Royal Observatory in Greenwich (England). The Greenwich meridian, as the prime meridian, is the starting point for calculating longitude. Longitude is given as the angle between the center of the prime meridian of the Earth's center and the center of the Earth's center. The Greenwich meridian has an angle of 0, and the opposite longitude, along which the date line runs, has an angle of 180 degrees.

How to find latitude and longitude on a map?

Definition of exact geographical location on the map depends on its scale. To do this, it is enough to have a map with a scale of 1/100000, or better - 1/25000.

First, longitude D is determined using the formula:

D =G1 + (G2 - G1) * L2 / L1,

where G1, G2 - the value of the right and left nearest meridians in degrees;

L1 is the distance between these two meridians;

Longitude calculation, for example, for Moscow:

G1 = 36°,

G2 = 42°,

L1 = 252.5 mm,

L2 = 57.0 mm.

The desired longitude = 36 + (6) * 57.0 / 252.0 = 37° 36".

We determine the latitude L, it is determined by the formula:

L =G1 + (G2 - G1) * L2 / L1,

where G1, G2 - the value of the nearest lower and upper latitude in degrees;

L1 - distance between these two latitudes, mm;

L2 - distance from the definition point to the nearest left one.

For example, for Moscow:

L1 = 371.0 mm,

L2 = 320.5 mm.

The required width L = 52 "+ (4) * 273.5 / 371.0 = 55 ° 45.

We check the correctness of the calculation; to do this, we need to find the latitude and longitude coordinates on the map using online services on the Internet.

We establish that the geographic coordinates for Moscow correspond to the calculations performed:

55° 45" 07" (55° 45" 13) north latitude;
37° 36" 59" (37° 36" 93) east longitude.

Determining location coordinates using iPhone

The acceleration of the pace of scientific and technological progress at the present stage has led to revolutionary discoveries of mobile technology, with the help of which a quick and more accurate determination of geographical coordinates has become available.

There are various mobile applications for this. On iPhones this is very easy to do using the Compass app.

Determination order:

To do this, click “Settings” and then “Privacy”.
Now click on “Location Services” at the very top.
Scroll down until you see and tap the compass.
If you see that it says "When used on the right side", you can start defining.
If not, tap it and select "While using an app."
Open the Compass app and you'll see your current location and current GPS coordinates at the bottom of the screen.

Determining coordinates in an Android phone

Unfortunately, Android doesn't have an official built-in way to get GPS coordinates. However, it is possible to get Google Maps coordinates, which requires some additional steps:

Open Google Maps on your Android device and find the desired location.
Tap and hold it anywhere on the screen and drag it to Google Maps.
Information or detailed map.
Find the Share option on the information map in the upper right corner. This will bring up a menu with a Share option.

This setup can be done in Google Maps on iOS.

This is a great way to get coordinates that doesn't require you to install any additional applications.

Many of us became familiar with such concepts as longitude and latitude in childhood thanks to the adventure novels of Stevenson and Jules Verne. People have been studying these concepts since ancient times.

In that era when there were no perfect navigation instruments in the world, it was the geographic coordinates on the map that helped sailors determine their location at sea and find their way to the desired areas of land. Today, latitude and longitude are still used in many sciences and make it possible to accurately determine the position of any point on the earth's surface.

What is latitude?

Latitude is used to set the location of an object relative to the poles. The main imaginary line runs at the same distance from and globe– equator. It has zero latitude, and on both sides of it there are parallels - similar imaginary lines that conventionally intersect the planet at equal intervals. To the north of the equator there are northern latitudes, to the south, respectively, southern latitudes.

The distance between parallels is usually measured not in meters or kilometers, but in degrees, which allows you to more accurately determine the position of the object. There are 360 degrees in total. Latitude is measured north of the equator, that is, points located in the Northern Hemisphere have a positive latitude, and points located in the Southern Hemisphere have a negative latitude.

For example, the north pole lies at a latitude of +90°, the south pole - -90°. Additionally, each degree is divided into 60 minutes, and minutes into 60 seconds.

What is longitude?

To find out the location of an object, it is not enough to know this place on the globe relative to the south or north. In addition to latitude, longitude is used for the full calculation, establishing the position of a point relative to east and west. If in the case of latitude the equator is taken as a basis, then longitude is calculated from the prime meridian (Greenwich), passing from the North to the South Pole through the London Borough of Greenwich.

On the right and left sides of the Greenwich meridian, ordinary meridians are drawn parallel to it, which meet each other at the poles. Eastern longitude is considered positive, and western longitude is negative.

Like latitude, longitude has 360 degrees, divided into seconds and minutes. To the east of Greenwich is Eurasia, towards the west - South and North America.

What are latitude and longitude used for?

Imagine that you are sailing on a ship lost in the middle of the ocean, or moving through an endless desert, where there are no signs or indicators at all. How could you explain your location to rescuers? It is latitude and longitude that help to find a person or other object anywhere on the globe, no matter where it is.

Geographic coordinates are actively used on maps search engines, in navigation, on ordinary geographical maps. They are present in surveying instruments, satellite positioning systems, GPS navigators and other tools needed to determine the location of a point.

How to set geographic coordinates on a map?

To calculate the coordinates of an object on the map, you must first determine in which hemisphere it is located. Next, you need to find out between which parallels the desired point is located and set the exact number of degrees - usually they are written on the sides geographical map. After this, you can proceed to determining longitude, first establishing in which hemisphere the object is located relative to Greenwich.

Determining degrees of longitude is similar to latitude. If you need to find out the location of a point in three-dimensional space, its height relative to sea level is additionally used.