Earth
lastmod 2014-07-09created 2014-07-091 edits
Earth is the third planet of the Solar System and the largest of the Solar System's terrestrial planets. Earth formed 4.567 billion years ago and has as its satellite the Moon, which was created by a violent collision with it. The two line segments represent the meridian and the equator. Surrounded by a thin layer of atmosphere, it is the planet where the living things known so far can live. The distance from the Sun to Earth is about 150 million kilometers. Earth is not a perfect sphere but close to a spheroid; however, its equatorial radius is about 6378 kilometers and its polar radius about 6357 kilometers, a difference of only about 20 kilometers, so its flattening is very low. What we commonly call body weight refers to a person's weight as measured on Earth.