How can we accurately predict our position on our planet?
We can accurately know the position of any place on earth with the help of two imaginary lines running across the earth’s surface, called Latitudes and Longitudes. The meeting place where these lines cross each other is known as co-ordinates.
How are Latitudes and Longitudes measured?
- The Greeks and various people over time, have been credited with calculating the circumference of the earth and include Plato and Archimedes. But the accepted circumference as we know today (40,075 km) has been accurately(with 1% error) calculated by Aryabhata from India(Born in 476 BC) and Eratosthenes from Greece (Born in 270 BC).
- The imaginary line running around the middle of a spherical earth is known as the equator. Latitudes are horizontal, imaginery lines, running around parallelly and at, equal distances above and below the equator. The distance between them is calculated at degrees, minutes and seconds.
- The equator is at 0 degrees.
- The earth is divided into 181 latitudes.
- Longitudes are imaginery lines running from the North Pole to the South Pole at the earth’s circumference. The lines of longitudes are often called meridians.
- The earth is divided into 360 longitudes.
- Greenwich is the designated 0 degrees longitude, since 1884. It was decided after a vote that involved 25 nations. The reason being the Royal Observatory was involved in generating accurate navigational information for 100s of years.
Why are Latitudes and Longitudes important?
- For centuries man has been venturing on journeys of discovery into the unknown seas. Latitudes and longitudes help in navigational charts, as the sea has no defined markers. Traveller and navigators through time have used the North Star or the Southern Cross Constellation to accurately pinpoint their position, depending which side of the equator they were on. Latitudes and Longitudes helped prepare maps, based on the positions of constellations.
- The latitudes and longitudes help us set time zones for the planet, based on earth’s rotation on it’s axis.
- The latitudes and longitudes help us locate an exact place on earth, based on the point where the latitudes and longitudes meet.
- Latitudes and longitudes help us predict weather and climatic changes, like for instance, the path of a cyclone or a storm.
- Our modern day Global Positioning Systems(GPS) are configured using latitudes and longitudes for satellite mapping of the earth and are used for tracking and route mapping.
Halley meridian and Bradley meridian
There are already two other meridian lines running through Greenwich, which were used before the 1884 conference, in Washington.
The Halley meridian was defined in 1721, by the English astronomer Edmond Halley, while the Bradley meridian of 1750, is still used as the standard definition of zero longitude in modern Ordnance Survey maps, which began in 1801, and have not moved onto the new system.