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Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being an ocean 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 Earth's crust.
Superior planets: Planets whose orbits lie outside the orbit of Earth. [nb 1] Jupiter, Saturn, Uranus and Neptune: Trojan planet: A planet co-orbiting with another planet. The discovery of a pair of co-orbital exoplanets has been reported, but later retracted. [3] One possibility for the habitable zone is a trojan planet of a gas giant close to ...
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.
A planetary core consists of the innermost layers of a planet. [1] Cores may be entirely liquid, or a mixture of solid and liquid layers as is the case in the Earth. [2] In the Solar System, core sizes range from about 20% (the Moon) to 85% of a planet's radius .
Earth is the only planet in the galaxy known to support life. Earth has many places that are suitable for humans to live in, although some areas of the planet can be very dangerous, too. About 71% of Earth's surface is covered in salt water oceans. Earth is the only place in the Solar System where liquid water is known to exist at present.
Terrestrial planets are substantially different from the giant planets, which might not have solid surfaces and are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. Terrestrial planets have a compact, rocky surfaces, and Venus, Earth, and Mars each also has an atmosphere. Their size, radius ...
The average magnetic field strength in Earth's outer core is estimated to be 2.5 millitesla, 50 times stronger than the magnetic field at the surface. [9] [10] As Earth's core cools, the liquid at the inner core boundary freezes, causing the solid inner core to grow at the expense of the outer core, at an estimated rate of 1 mm per year.
Although many celestial bodies in the Solar System have a hydrosphere, Earth is the only celestial body known to have stable bodies of liquid water on its surface, with oceanic water covering 71% of its surface, [2] which is essential to life on Earth. The presence of liquid water is maintained by Earth's atmospheric pressure and stable orbit ...