The Earth is the third planet from the Sun and the only planet that supports life in the planetary system. This is enabled by Earth being a water world, the only one in the solar system sustaining liquid surface water. Almost all of Earth’s water is contained in its global ocean, covering 70.8% of the Earth’s surface. The remaining 29.2% of Earth’s surface is land, most of which is located in the form of continental landmasses within one hemisphere, Earth’s land hemisphere. Earth’s land is part of Earth’s crust, consisting of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Inside Earth’s crust is a liquid outer core that generates the magnetosphere, deflecting most of the destructive solar winds and cosmic radiation.Earthl

• Earth has a dynamic atmosphere, which sustain surface conditions and protects it from most meteoroids and UV-light entry. It has a composition of primarily nitrogen and oxygen. Water vapour is widely present in the atmosphere, forming clouds that cover most of the planet. It is the densest planer in the solar system. Of the four rocky planets, it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it, taking a year (about 365.25 days) to complete one revolution. Earth rotatesaround its own axis in slightly less than a day (in about 23 hours and 56 minutes). Earth’s axis of rotation is tilted with respect to the perpendicular to its orbital plane around the Sun, producing seasons. Earth is orbited by one permanent natural satellite, the Moon, which orbits Earth at 384,400 km (1.28 light seconds) and is roughly a quarter as wide as Earth. Through tidal locking, the Moon always faces Earth with the same side, which causes tided, stabilizes Earth’s axis, and gradually slows its rotation.

Earth, like most other bodies in the Solar System, formed 4.5 billion years ago from gas in the early solar system. During the first billion years of Earths history, the ocean formed and then life develoed within it. Life spread globally and has been altering Earth’s atmosphere and surface, leading to the Great Oxidation Event two billion years ago. Humans emerged 300,000 years ago in Africa and have spread across every continent on Earth with the exception of Antarctica. Humans depend on Earth’s biosphere and natural resources for their survival.