Earth

Earth is a unique planet in many ways. It is the planet that we live on and it is the only known planet to have life. Life on Earth is possible because of the presence of oxygen and water. 71% of the Earth's surface is covered with liquid water. The presence of liquid water is unique among the planets. This water, mainly in the form of oceans helps to moderate the temperature of the Earth. Earth is the third planet from the sun and the fifth largest.

Earth's atmosphere has changed over time. Today it is mainly nitrogen and oxygen. However, originally there was a much larger amount of carbon dioxide in the atmosphere. This carbon dioxide has accumulated in carbonate rocks.

Earth is the densest of all the planets. It also has a unique composition because its crust is divided into solid plates that float on a hot mantle. Plate tectonics greatly affect the Earth's surface. As the plates move they cause mountains and trenches to form, and earthquakes and volcanoes to occur. Water on Earth also affects its surface, causing large amounts of erosion. As a result of these processes, Earth has a very young surface. There is very little evidence about the Earth when it first formed.

moons: 1; name=Moon