Earth

Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is made possible 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. The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is at least somewhat humid and covered by vegetation, while large ice sheets at Earth's polar deserts retain more water than Earth

320px|thumb|Image of the physical world, captured by the Hubble Space Telescope

all living and non-living things occurring naturally on Earth or some region thereof

fields of science dealing with planet Earth and its nearby planets in space

evolution of Earth throughout times

rotation of Earth around its axis

thumb|Precession of a gyroscope thumb|

paradigm that living organisms interact with their surroundings in a self-regulating system

unit of mass equal to that of Earth

gravitationally curved trajectory Earth travels around the Sun

acceleration that the Earth imparts to objects on or near its surface

accounting of the energy flows which determine Earth's surface temperature and drive its climate

possible upcoming scenarios for Earth

mean distance from the Earth's center to its surface

hypothesis that complex extraterrestrial life is a very improbable phenomenon and likely to be extremely rare

major geological occurrences in Earth's past

threshold that, when exceeded, can lead to large change in the Earth system

overview about the location of Earth in the Universe

point on the surface of a planet where the sun's rays strike the planet exactly perpendicular to its surface

mathematical descriptions of Earth's complex shape

assertion that the Earth is (at least approximately) spherical

hypotheses for the possible sources of the water on Earth

shadow that the Earth casts on its own atmosphere

time standard for astronomical observations from the Earth

methods to prevent destructive asteroid hits

philosophical concept

thermal energy stored in ocean water

accounting of the energy flows at and below the planet's crust

supernova that occurs close enough to the Earth to have noticeable effects on its

astronomical event in which the Earth comes between Mars and the Sun

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phases of the Earth as seen from the Moon

overview of the distribution of water on planet Earth

astrobiological hypothesis that life forms of early Earth were retinal-based rather than chlorophyll-based, making Earth appear purple rather than green

metaphor for Humankind's conditions in the Anthropocene

circle of latitude

thumb|right|A series of images made by ultraviolet light imager on the Polar (satellite)|Polar spacecraft showing the aurora and Earth's upper atmosphere. The glowing side is the atmosphere lit up by the Sun's light energy and the oval of light is the aurora. During a substorm the auroral oval brightens in a localized area and then suddenly breaks into many different forms that expand both toward Earth's pole and equator. This is exactly what Shun-ichi Akasofu (1964) drew in his auroral substorm illustration. thumb|Short video featuring commentary by David Sibeck, project scientist for the THE

opposing climate states on Earth

the distance around the Earth, either around the equator or around the poles

global human population statistics

geomagnetic reversal that occurred approximately one million years ago

distance measured along the surface of the earth

consolidation of the Earth's crust

short-term changes in the length of the day