Planet earth biography

Earth, our home, is the third planet from the sun. While scientists continue to hunt for clues of life beyond Earth, our home planet remains the only place in the universe where we've ever identified living organisms. 

Earth is the fifth-largest planet in the solar system.

It's smaller than the four gas giants — Jupiter, Saturn, Uranus and Neptune — but larger than the three other rocky planets, Mercury, Mars and Venus.

Earth has a diameter of roughly 8,000 miles (13,000 kilometers) and is mostly round because gravity generally pulls matter into a ball.

But the spin of our home planet causes it to be squashed at its poles and swollen at the equator, making the true shape of the Earth an "oblate spheroid."

Related: How big is Earth?

Our planet is unique for many reasons, but its available water and oxygen are two defining features.

Water covers roughly 71% of Earth's surface, with most of that water located in our pl