A few years ago, the weather forecast used the earth.

The earth is one of the eight planets in the solar system, ranking third in the order from near to far from the sun. It is also the earth-like planet with the largest diameter, mass and density in the solar system, with a distance of1.500 million kilometers from the sun. The earth rotates from west to east and revolves around the sun at the same time. Existing for 4-4.6 billion years, [1]? It has a natural satellite-the moon, forming a celestial system-the earth-moon system. It originated from the primitive solar nebula 4.6 billion years ago.

The equatorial radius of the earth is 6378. 137km, the polar radius is 6356.752km, the average radius is about 637 1km, and the equatorial circumference is about 40076km. It is an irregular elliptical sphere with slightly flat equator and slightly protruding poles. The surface area of the earth is 5 1 100 million square kilometers, of which 7 1% is ocean and 29% is land. Seen from space, the earth looks blue.

There are core, mantle and shell structures inside the earth, and hydrosphere, atmosphere and magnetic field outside the earth. The earth is the only known celestial body with life in the universe at present, and it is the home of millions of creatures, including human beings. [ 1]?