MAPPING OF THE EARTH SUB TOPIC- THE GRID SYSTEM: LATITUDE AND LONGITUDE CLASS-6 MADE BY –SANANDA SARKAR A grid system or grid coordinate system defines the location of points from the distance travelled along two perpendicular axis from some stated origin.In the example following diagram the two axes or labelled x and y.The origin is located in the lower left corner. Unit distance travelled along each axis from the origin is shown. In this coordinate system, the value associated with the x-axis is given first following by the value assigned from the y axis. Hence we can say x axis represent as latitude which runs by parallels & Y axis represent for longitude which run by vertically. These entire system known as grid system. LATITUDE AND LONGITUDE The lines of latitude are called parallels or also commonly referred to as the parallels of latitude. It is formed by the circles found on the globe which is parallel to the Earth’s equator and are equally spaced within the 90 degrees from North (with positive degrees of latitude) and South (with negative degrees of latitude). There are five major parallels of latitude from north to south and these are as follows: The equator with a parallel of 0° because this is where the parallels of latitude begins, Tropic Cancer with a parallel of 23°27’ N, Arctic Circle with a parallel of 66°33’ N, Tropic of Capricorn with a parallel of 23°27’ S and Antarctic Circle with a parallel of 66°33’ S. A (geographic) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. IMPORTANCE OF LATITUDE AND LONGITUDE INTERNATIONAL DATE LINE International Date Line, also called Date Line, imaginary line extending between the North Pole and the South Pole and arbitrarily demarcating each calendar day from the next. It corresponds along most of its length to the 180th meridian of longitude but deviates eastward through the Bering Strait to avoid dividing Siberia and then deviates westward to include the Aleutian Islands with Alaska. South of the Equator, another eastward deviation allows certain island groups to have the same day as New Zealand. The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. TRIVIA Circumference of the equator is 40,075.16km (24,901.55miles). Earth’s circumference between the north &south pole (24,859.82 miles)(40,008). Earth’s diameter at the Equator (7,926.82 miles)(12,756.4km). Earth’s diameter at the poles (7,899.80 miles)(12,73.5km). .