Each place on earth can be identified by a global latitude and longitude coordinate system. Knowing these parameters, it is easy to find any location on the planet. For several centuries now, a coordinate system has been helping people in this.
Historical background of the origin of geographical coordinates
When people began to travel long distances through deserts and seas, they needed a way to fix their position and know which direction to move in order not to get lost. Before latitude and longitude appeared on the map, the Phoenicians (600 BC) and the Polynesians (400 BC) used the starry sky to calculate latitude.
Over the centuries, fairly sophisticated devices have been 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 the gnomon is just a vertical stick that casts a shadow from the sun, then kamal is a very peculiar 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 tools determined the latitude even after the invention of the magnetic compass, until then, until they invented a reliable method for determining latitude and longitude on the map.
For hundreds of years, navigators have not had an accurate idea of location due to the lack of a concept of the meaning of longitude. There was no exact time device in the world, such as a chronometer, so calculating longitude was simply impossible. Not surprisingly, early navigation was problematic and often led to shipwrecks.
No doubt, the pioneer of revolutionary navigation was Captain James Cook, who traveled the expanses of the Pacific Ocean thanks to the technical genius Henry Thomas Harrison. In 1759, Harrison developed the first navigational watch. Keeping the exact average GMT, Harrison’s watches allowed the sailors to determine how many hours were at the point of the prime meridian and at the location, after which it became possible to determine the longitude from east to west.
Geographic coordinate system
A geographic coordinate system defines two-dimensional coordinates based on the surface of the Earth. It has an angular unit of measure, a primary meridian and an equator with zero latitude. The globe is conventionally divided into 180 degrees of latitude and 360 degrees of longitude. The lines of latitude are parallel to the equator; they are horizontal on the map. Longitude lines connect the North and South poles; they 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 unique latitude and longitude for each position on Earth. To increase the accuracy of measurements, they are further subdivided into 60 minutes, and each minute into 60 seconds.
Latitude
The equator is located at right angles to the axis of the Earth, about halfway between the North and South poles. At an angle of 0 degrees, it is used in the geographical coordinate system as a starting point for calculating latitude and longitude on the map.
Latitude is defined as the angle between the equatorial line of the center of the Earth and the location of its center. The North and South Poles have an angle of 90 degrees. To distinguish places in the Northern Hemisphere from the Southern Hemisphere, the width is additionally provided in the traditional spelling with N for the north or S for the south.
The earth is tilted by about 23.4 degrees, so to find the latitude at the summer solstice, you need to add 23.4 degrees to the angle that is measured.
How to determine latitude and longitude on a map during the winter solstice? To do this, subtract 23.4 degrees from the angle that is 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 angle of inclination of the Earth and, therefore, latitude by looking at the angle of the North Star. At the North Pole, it will be 90 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 located at 66 degrees 34 minutes north and, accordingly, south latitude. These latitudes limit the area around the poles where the sun does not set at the summer solstice, which is why the midnight sun prevails there. In the winter solstice, the sun does not rise here, the polar night sets in.
- The tropics are at 23 degrees 26 minutes in the northern and southern latitudes. These latitudinal circles mark the solar zenith with the summer solstice of the northern and southern hemispheres.
- The equator lies at a latitude of 0 degrees. The equatorial plane passes approximately in the middle of the axis of the Earth between the north and south poles. The equator is the only circle of latitude corresponding to the circumference of the Earth.
Longitude Definition
Latitude and longitude on the 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 when the sun rises and falls. The Greenwich Meridian is indicated by 0 degrees 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 the sunset time of a location and another famous place, you can understand how far east or west is from it.
Longitude lines 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 zero line of longitude, which measures the east-west direction in a system of geographical coordinates (such as latitude and longitude on the map). In fact, the zero line passes through the Royal Observatory in Greenwich (England). Greenwich Meridian as zero is the starting point for calculating longitude. Longitude is defined as the angle between the center of the zero 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 geographical location on a 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, determine the longitude D 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 is the distance from the definition point to the nearest left.
Longitude calculation, for example, for Moscow:
G1 = 36 °
G2 = 42 °
L1 = 252.5 mm
L2 = 57.0 mm.
Searched 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 lower and upper nearest latitude in degrees;
L1 is the distance between these two latitudes, mm;
L2 is the distance from the definition point to the nearest left.
For example, for Moscow:
G1 = 56 °
G2 = 52 °
L1 = 371.0 mm
L2 = 320.5 mm.
The desired width L = 52 '+ (4) * 273.5 / 371.0 = 55 ° 45.
We check the correctness of the calculation, for this it is necessary to find the latitude, longitude coordinates on the map using online services on the Internet.
We establish that the geographical coordinates for the city of Moscow correspond to the calculations performed:
- 55 ° 45 '07 "(55 ° 45' 13) north latitude;
- 37 ° 36 '59 "(37 ° 36' 93) East.
Locate your location using iPhone
The acceleration of the pace of scientific and technological progress at the present stage has led to the revolutionary discoveries of mobile technology, with the help of which a quick and more accurate determination of geographical coordinates became available.
There are various mobile applications for this. On iPhone phones, this is very easy to do using the Compass app.
The procedure for determining:
- To do this, click "Settings", and then - "Privacy".
- Now click on “Location Services” at the very top.
- Scroll down until you see the compass and touch 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 application."
- Open the Compass app and you will see your current location and current GPS coordinates at the bottom of the screen.
Positioning on an Android Phone
Unfortunately, Android does not have an official built-in way to get GPS coordinates. Nevertheless, it is possible to get the coordinates of Google Maps, which requires some additional steps:
- Open Google Maps on your Android device and find the desired definition point.
- Touch 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 info card in the upper right corner. This will bring up a menu with the Share option.
This setting can be done in Google Maps on iOS.
This is a great way to get the coordinates, which does not require installing any additional applications.