地球部分（Part of the earth）.doc

地球部分（Part of the earth） Basic knowledge - part of the earth (1) earth (shape and size, latitude and longitude) 1. Shape and size: The shape of the earth is a slightly flat, irregular sphere. The average radius of the earth is 6371 km, the equator is 6378 kilometers and the radius is 6357 kilometers. The equator is about 40,000 kilometers in circumference. (1) axis earths axis of rotation (2) the poles cross the center of the earth and intersect the earths surface at two points. A point that points to the north star, or the north, is called the North Pole; The opposite of the North Pole is the South Pole. Latitude and longitude, longitude and longitude (1) weft: the weft line is round, also known as the weft circle, and the length varies. The equator is the longest and is gradually shortened from the equator to the poles. The latitude indicates the direction of things. Latitude: the equator is the zero parallel. The latitude north of the equator is called north latitude, and the code is called N. The latitude south of the equator is called latitude, and the code name is S. 90 ° north latitude, south of the equator. The distance of one latitude is about 11,1km. In the low latitude, weft and achieve the division: low latitudes 0 ° to 30 °; Middle latitude 30 ° ~ 60 °; High latitude 60 ° ~ 90 ° North and south hemispheres: north of the equator in the northern hemisphere, south of the equator in the southern hemisphere. (2) meridian: also called meridian. The longitude line is semicircle, all of the longitude lines. Everything on the earth is formed from the surface of the earths surface, which is called a coils. The meridian indicates the north-south direction. Longitude: in fact longitude is the Angle between two lines. The international rules, through the site at the royal observatory Greenwich, London, United Kingdom, the centerline of the a meridian at 0 ° meridian, also called the prime meridian. From the prime meridian, each divided into 180 degrees to the west, e