Earth is the third planet from the sun. It has an atmosphere of mainly nitrogen and oxygen, and a extensive hydrosphere which covers more the 70% of the surface. Earth is a home to many animals, plants, fungi and bacteria, including Humans. Earth has one moon, Called "Moon", "the Moon" or "Luna". Earth is also called "Gaia", "Terra" and "the world", although this can also be said in the sense of the whole universe. Earth is one of three rocky bodies in the solar system that exhibit a global geomagnetic field, the others being Mercury and Ganymede.