Earth is a rocky planet orbiting the Sun in the Solar System in the Milky Way Galaxy, and the third planet in order from its star. Earth has three alternate names in Latin, also common in other languages: Tellus, Terra and Gaia.
The planet is the home of millions of species of lifeforms, including the Terrabots and the Humans. Its small natural satellite, the Moon, is inhabited by the Lunabots. Approximately 4.54 billion years ago, Earth was brought into existence in a creation event by the Terrabots. Not long after, the Lunabots brought the Moon into existence in another creation event to stabilize the Earth.
Earth's equatorial radius is 6,378.1 km, mean radius is 6,371.0 km, and polar radius is 6,356.8 km. In the first billion years of Earth, life appeared on its surface.
Earth's lithosphere is divided into several rigid segments, or tectonic plates, that migrate across the surface over periods of many millions of years. About 71% of the surface is covered by salt water oceans, with the remainder consisting of continents and islands which together have many lakes and other sources of water that contribute to the hydrosphere. Earth's poles are mostly covered with ice that is the solid ice of the Antarctic ice sheet and the sea ice that is the polar ice packs. The planet's interior remains active, with a solid iron inner core, a liquid outer core that generates the magnetic field, and a thick layer of relatively solid mantle. Earth orbits at 1 astronomical unit from the Sun.