Earth is the third planet from the Sun; the fifth-largest of the eight primary planets in the Solar System. It is also the largest of the Solar System's four terrestrial (rocky) planets. It is sometimes referred to as the "world", the "Blue Planet", or by any of its Latin names, Terra or Tellus. The Earth is the homeworld of the human species, and the capital of all human colonies.
70% of Earth's surface is covered with water. There are seven major landmasses, also called "continents", where civilized areas are concentrated. The poles are covered in ice while the equator regions are either tropical or desert. Other regions include temperate zones, in which the majority of humans live.