Earth
Our home planet, the only known planet with life
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water.
Sources:
Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle.
Sources:
The total surface area of Earth is about 510 million km². Earth's surface is continually reshaped by internal plate tectonics and by erosion and weathering. Plate tectonics has caused the formation of mountain ranges and ocean trenches.