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Description

This diagram shows the the seasons and orbit of the Earth.

Earth, the Earth, or Terra is the third planet from the Sun, located in the Inner Solar System. It is the only place known in the universe where life has originated and found habitability. While Earth may not contain the largest volumes of water in the Solar System, only Earth sustains liquid surface water, extending over 70.8% of the Earth with its ocean, making Earth an ocean world. Earth's polar regions currently retain most of all other water with large sheets of ice covering ocean and land, dwarfing Earth's groundwater, lakes, rivers and atmospheric water. Land, consisting of continents and islands, extends over 29.2% of the Earth and is widely covered by vegetation.
Earth has an atmosphere, which sustains Earth's surface conditions and protects it from most meteoroids, radiation, and UV-light at entry. It has a composition of primarily nitrogen and oxygen. It has a average surface temperature of 33.8°F Earth is rounded into an ellipsoid with a circumference of about 25,000 mi (40 megameters). It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about 8.3 light-minutes (9.3×10⁷ miles) away from the Sun and orbits it, taking 365 days to complete one revolution. The Earth rotates around its own axis in about 24 hours. The 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 or Luna, which orbits Earth at 239,000 mi (1.28 light seconds) and is roughly one quarter as wide as Earth. Through tidal locking, the Moon always faces the Earth with the same side, which causes tides, stabilizes Earth's axis, and gradually slows its rotation.

The Earth is about 4.54×10⁹ years old, roughly one third as old as of the Universe.Earth, like most other bodies in the Solar System, formed from gas in the early Solar System. During the first 10⁹ years of Earth's history, the ocean formed and then life developed within it. Life spread globally and has been altering Earth's atmosphere and surface, leading to the Great Oxidation Event 2×10⁹ years ago. Humans emerged 300 millennia ago, and have reached a population of 8×10⁹ today. Humans depend on Earth's biosphere and natural resources for their survival, but have increasingly impacted the planet's environment. Humanity's current impact on Earth's climate and biosphere is unsustainable, threatening the livelihood of humans and many other forms of life, causing widespread extinctions. an average diameter of 7,918 mi, making it the fifth largest planetary sized and largest terrestrial object of the Solar System. Due to Earth's rotation it has the shape of an ellipsoid, bulging at its Equator, reaching 27 mi further out from its center of mass than at its poles.
Since Earth's surface is farthest out from Earth's center of mass at its equatorial bulge, the summit of the volcano Chimborazo in Ecuador (3,967.1 mi) is its farthest point out. Earth's surface is the top layer of Earth's rigid or liquid structure, at the interface with its atmosphere. Earth as an idealized spheroid has a surface area of about 2×10⁸ mi². Earth can be divided into two hemispheres. Generally, Earth is divided by latitude into the polar Northern and Southern hemispheres, or by longitude into the continental Eastern and Western hemispheres. Regarding the surface distribution of land and water, Earth can be divided into an oceans-focused water hemisphere and a landmasses-focused land hemisphere.
Most of Earth's surface is made of water, in liquid form or in smaller amounts as ice. 70.8% of Earth's surface consists of the interconnected ocean, making it Earth's global ocean or world ocean. This makes Earth, along with its vibrant hydrosphere, a water world or ocean world, particularly in Earth's early history when the ocean is thought to have possibly covered Earth completely. The world ocean is commonly divided into the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic oceans, from largest to smallest. The ocean fills the oceanic basins. The ocean floor comprises abyssal plains, continental shelves, seamounts, submarine volcanoes, oceanic trenches, submarine canyons, oceanic plateaus, and a globe-spanning mid-ocean ridge system. Earth's land is 29.2% of Earth's surface area. Earth's land consists of many islands around the globe, but mainly of four continental landmasses, which are, from largest to smallest: Afro-Eurasia, America, Antarctica, and Australia. These landmasses are further broken down and grouped into the continents. The terrain varies greatly and consists of mountains, deserts, plains, plateaus, and other landforms. The elevation of the land surface varies from the low point of -1,371 ft at the Dead Sea, to a maximum altitude of 29,029 ft at the top of Mount Everest. The mean height of land above sea level is about 2,615 ft. Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or rheological properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity. The thickness of the crust varies from about 3.7 mi under the oceans to 19–31 mi for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, which is divided into independently moving tectonic plates.

Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 250 and 410 mi below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. Earth's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 6–30 arcminutes per year, although both somewhat higher and much lower rates have also been proposed. The radius of the inner core is about one-fifth of that of Earth. Density increases with depth, as described in the table on the right.
Among the Solar System's planetary-sized objects Earth is the object with the highest density.
1.3×10²⁷ lbs

Description

This diagram shows the the seasons and orbit of the Earth.

Earth, the Earth, or Terra is the third planet from the Sun, located in the Inner Solar System. It is the only place known in the universe where life has originated and found habitability. While Earth may not contain the largest volumes of water in the Solar System, only Earth sustains liquid surface water, extending over 70.8% of the Earth with its ocean, making Earth an ocean world. Earth's polar regions currently retain most of all other water with large sheets of ice covering ocean and land, dwarfing Earth's groundwater, lakes, rivers and atmospheric water. Land, consisting of continents and islands, extends over 29.2% of the Earth and is widely covered by vegetation.
Earth has an atmosphere, which sustains Earth's surface conditions and protects it from most meteoroids, radiation, and UV-light at entry. It has a composition of primarily nitrogen and oxygen. It has a average surface temperature of 33.8°F Earth is rounded into an ellipsoid with a circumference of about 25,000 mi (40 megameters). It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about 8.3 light-minutes (9.3×10⁷ miles) away from the Sun and orbits it, taking 365 days to complete one revolution. The Earth rotates around its own axis in about 24 hours. The 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 or Luna, which orbits Earth at 239,000 mi (1.28 light seconds) and is roughly one quarter as wide as Earth. Through tidal locking, the Moon always faces the Earth with the same side, which causes tides, stabilizes Earth's axis, and gradually slows its rotation.

The Earth is about 4.54×10⁹ years old, roughly one third as old as of the Universe.Earth, like most other bodies in the Solar System, formed from gas in the early Solar System. During the first 10⁹ years of Earth's history, the ocean formed and then life developed within it. Life spread globally and has been altering Earth's atmosphere and surface, leading to the Great Oxidation Event 2×10⁹ years ago. Humans emerged 300 millennia ago, and have reached a population of 8×10⁹ today. Humans depend on Earth's biosphere and natural resources for their survival, but have increasingly impacted the planet's environment. Humanity's current impact on Earth's climate and biosphere is unsustainable, threatening the livelihood of humans and many other forms of life, causing widespread extinctions. an average diameter of 7,918 mi, making it the fifth largest planetary sized and largest terrestrial object of the Solar System. Due to Earth's rotation it has the shape of an ellipsoid, bulging at its Equator, reaching 27 mi further out from its center of mass than at its poles.
Since Earth's surface is farthest out from Earth's center of mass at its equatorial bulge, the summit of the volcano Chimborazo in Ecuador (3,967.1 mi) is its farthest point out. Earth's surface is the top layer of Earth's rigid or liquid structure, at the interface with its atmosphere. Earth as an idealized spheroid has a surface area of about 2×10⁸ mi². Earth can be divided into two hemispheres. Generally, Earth is divided by latitude into the polar Northern and Southern hemispheres, or by longitude into the continental Eastern and Western hemispheres. Regarding the surface distribution of land and water, Earth can be divided into an oceans-focused water hemisphere and a landmasses-focused land hemisphere.
Most of Earth's surface is made of water, in liquid form or in smaller amounts as ice. 70.8% of Earth's surface consists of the interconnected ocean, making it Earth's global ocean or world ocean. This makes Earth, along with its vibrant hydrosphere, a water world or ocean world, particularly in Earth's early history when the ocean is thought to have possibly covered Earth completely. The world ocean is commonly divided into the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic oceans, from largest to smallest. The ocean fills the oceanic basins. The ocean floor comprises abyssal plains, continental shelves, seamounts, submarine volcanoes, oceanic trenches, submarine canyons, oceanic plateaus, and a globe-spanning mid-ocean ridge system. Earth's land is 29.2% of Earth's surface area. Earth's land consists of many islands around the globe, but mainly of four continental landmasses, which are, from largest to smallest: Afro-Eurasia, America, Antarctica, and Australia. These landmasses are further broken down and grouped into the continents. The terrain varies greatly and consists of mountains, deserts, plains, plateaus, and other landforms. The elevation of the land surface varies from the low point of -1,371 ft at the Dead Sea, to a maximum altitude of 29,029 ft at the top of Mount Everest. The mean height of land above sea level is about 2,615 ft. Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or rheological properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity. The thickness of the crust varies from about 3.7 mi under the oceans to 19–31 mi for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, which is divided into independently moving tectonic plates.

Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 250 and 410 mi below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. Earth's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 6–30 arcminutes per year, although both somewhat higher and much lower rates have also been proposed. The radius of the inner core is about one-fifth of that of Earth. Density increases with depth, as described in the table on the right.
Among the Solar System's planetary-sized objects Earth is the object with the highest density.
1.3×10²⁷ lbs