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. The coordinate system has been helping people in 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 in order not to get lost. Before latitude and longitude were on a map, the Phoenicians (600 BC) and Polynesians (400 AD) used the starry sky to calculate latitude.
Through the centuries quite complex devices have been developed, such as the quadrant, the astrolabe, the gnomon and the 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 the gnomon is just a vertical stick that casts a shadow from the sun, then the kamal is a very peculiar device.
It consisted of a rectangular wooden board measuring 5.1 by 2.5 cm, to which, through a hole in the middlea rope was attached with several equally spaced knots.
These instruments determined latitude even after the invention of the magnetic compass, until a reliable method of determining latitude and longitude on a map was invented.
Navigators for hundreds of years did not have an accurate idea of the location due to the lack of a concept of the value 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 expanses of the Pacific Ocean thanks to the technical genius of Henry Thomas Harrison. Harrison developed the first navigational clock in 1759. Keeping accurate Greenwich Mean Time, Harrison's watch allowed sailors to determine how many hours were at the prime meridian point and at the point of location, after which it became possible to determine the longitude from east to west.
Geographic coordinate system
Geographic coordinate system defines two-dimensional coordinates based on the surface of the Earth. It has an angular unit, a prime meridian, and an equator with zero latitude. The globe is conditionally divided into 180 degrees of latitude and 360 degrees of longitude. Lines of latitude are placed parallel to the equator, they 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 overlaygeographic 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.
Determination of latitude
The equator is located at right angles to the Earth's axis, approximately halfway 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 the 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 Poles have a width angle of 90. To distinguish places in the Northern Hemisphere from the Southern Hemisphere, the width is additionally provided in traditional spelling with N for north or S for south.
The earth is tilted 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 the latitude and longitude on the map during the winter solstice? To do this, subtract 23.4 degrees from the angle being measured. And in any other period of 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 tilt of the Earth, and therefore the latitude, by looking at the angle of the North Star. At the North Pole itwill be 90 from the horizon, and at the equator it will be directly ahead of the observer, 0 degrees from the horizon.
Important latitudes:
- The northern and southern polar circles, each 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 dominates there. On the winter solstice, the sun does not rise here, the polar night sets in.
- The tropics are at 23 degrees 26 minutes north and south. These latitudinal circles mark the solar zenith at the summer solstice of the northern and southern hemispheres.
- The equator lies at latitude 0 degrees. The equatorial plane runs 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.
Determination of longitude
Latitude and longitude on the map are important geographic coordinates. Longitude is much more difficult to calculate than latitude. The earth rotates 360 degrees a day, or 15 degrees an hour, so there is a direct relationship between longitude and the times the sun rises and sets. The Greenwich meridian is indicated by 0 degrees of longitude. The sun sets an hour earlier every 15 degrees east of it and an hour later every 15 degrees west. If you know the difference between a location's sunset time and another known location, you can figure out how far east or west it is.
Lines of longitude run from north to south. They converge at the poles. Andlongitude coordinates are between -180 and +180 degrees. The Greenwich meridian is the zero 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 specified as the angle between the center of the prime meridian of the center of the Earth and the center of the center of the Earth. 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?
Determining the exact geographic 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 by 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;
L2 – distance from the definition point to the left closest one.
Calculation of longitude, for example, for Moscow:
G1=36°, G2=42°, L1=252.5mm, L2=57.0 mm.
Desired longitude=36 + (6)57, 0 / 252, 0=37° 36'.
Determine the latitude L, it is determined by the formula:
L=G1 + (G2 - G1)L2 / L1, where G1, G2 - the value of the lower and upper nearest latitude indegrees;
L1 – distance between these two latitudes, mm;
L2 – distance from the definition point to the left closest one.
For example, for Moscow:
G1=56°, G2=52°, L1=371.0 mm, L2=320.5mm.
Desired width L=52 '+ (4)273.5 / 371.0=55 ° 45.
Checking the correctness of the calculation, for this you need to use online services on the Internet to find the coordinates of latitude, longitude on the map.
Set that the geographical coordinates for the city of Moscow correspond to the calculations:
- 55° 45' 07" (55° 45' 13) N;
- 37° 36' 59" (37° 36' 93) East.
Determining the coordinates of the location using the 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 faster 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.
Determining order:
- To do this, click "Settings", and then - "Privacy".
- Now click "Location Services" at the very top.
- Scroll down until you see the compass and tap it.
- If you see that it says "When used on the right side", you can start the definition.
- If not, tap it and select"When using the app."
- Open the Compass app and you will see your current location and current GPS coordinates at the bottom of the screen.
Determination of 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 fix point.
- Press and hold it anywhere on the screen and drag it to Google Maps.
- An informational or detailed map will appear at the bottom.
- Find the Share option on the information card in the upper right corner. This will bring up a menu with the Share option.
This setup can be done in Google Maps on iOS.
This is a great way to get coordinates without having to install any additional apps.
