Traditional Culture Encyclopedia - Weather forecast - How big is our earth?

How big is our earth?

The equatorial radius of the earth is 6378. 137 km, the polar radius is 6356.752 km, the average radius is about 637 1 km, and the equatorial circumference is about 40076 km. It is an irregular oval sphere with slightly flat poles and slightly bulging equator. 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.

Extended data:

The position of the earth

The position of the earth in the universe has been fundamentally expanded in the last century. At first, the earth was considered as the center of the universe, but at that time, the understanding of the universe only included those planets visible to the naked eye and seemingly fixed stars on the celestial sphere.

Heliocentrism was widely accepted in the17th century. Later, William Herschel and other astronomers discovered that the sun was located in a disk galaxy composed of stars. By the 20th century, the observation of spiral nebulae showed that our Milky Way was just one of billions of galaxies in the expanding universe.

2 1 century, the overall structure of Hubble volume began to become clear-supercluster formed a huge network structure containing large-scale fibers and holes. Supergalaxy clusters, large-scale fiber structures and holes may be the largest coherent structures in the universe.

On a larger scale (more than one billion parsec), the universe is homogeneous, that is, its parts have the same density, composition and structure on average.

? Baidu Encyclopedia-Earth History

Baidu Encyclopedia-Earth