Earth

The Earth is the third planet from the Sun. It is one of the four terrestrial planets in our Solar System. This means most of its mass is solid. The other three are Mercury, Mars, and Venus. The Earth is also called the Blue Planet, Planet Earth, and Terra.

Science shows that Earth formed around 4.5 billion years ago. The organnisms that live on Earth have completely changed its air (atmosphere); this is called a biosphere. 71% of Earth's surface is covered in salt water oceans. Earth is the only place in the Solar System where liquid water is known to exist at present. The other 29% is made of rocky land in the shape of continents and islands. Earth interacts with other objects