Earth (or, "the earth") is the only planet presently known to support life, and its natural features are the subject of many fields of scientific research. Within the solar system, it is third closest to the sun; it is the largest terrestrial planet and the fifth largest overall. Its most prominent climatic features are its two large polar regions, two relatively narrow temperate zones, and a wide equatorial tropical to subtropical region. Precipitation varies widely with location, from several metres of water per year to less than a millimetre. 71 percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the Northern Hemisphere.
Earth has evolved through geological and biological processes that have left traces of the original conditions. The outer surface is divided into several gradually migrating tectonic plates. The interior remains active, with a thick layer of plastic mantle and an iron-filled core that generates a magnetic field.
The atmospheric conditions have been significantly altered from the original conditions by the presence of life-forms, which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by latitude and other geographic factors, the long-term average global climate is quite stable during interglacial periods, and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.
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Other articles related to "earth":
... and the mass of a given astronomical body such as the Sun or the Earth—is known as the standard gravitational parameter and is denoted ... Also, for celestial bodies such as the Earth and the Sun, the value of the product GM is known more accurately than each factor independently ... For Earth, using M⊕ as the symbol for the mass of the Earth, we have Calculations in celestial mechanics can also be carried out using the unit of solar mass rather than the ...
... abduct her, bursting through a cleft in the earth ... daughter had disappeared, searched for her all over the earth with torches ... In most versions she forbids the earth to produce, or she neglects the earth and in the depth of her despair she causes nothing to grow ...
... Main article Earth in culture The standard astronomical symbol of the Earth consists of a cross circumscribed by a circle ... Earth has often been personified as a deity, in particular a goddess ... recall a story involving the creation of the Earth by a supernatural deity or deities ...
2004 FH is a near-Earth asteroid that was discovered on March 15, 2004, by the NASA-funded LINEAR asteroid survey ... and passed just 43,000 km (27,000 mi) above the Earth's surface on March 18, 2004, at 2208 UTC making it the 11th closest approach to Earth recorded as of 21 November ... comparison, geostationary satellites orbit Earth at 35,790 km ...
... known by the temporary name AL00667, is a near-Earth asteroid, first discovered on January 13, 2004, by the LINEAR project ... Center (MPC) suggesting an imminent collision with Earth on or about January 15 with a likelihood of 14 ... The asteroid passed at a distance of 12 Gm (or 32 times the distance from the Earth to the Moon), posing no threat ...
Famous quotes containing the word earth:
“I must remind you that our credulity is not to be measured by the truth of the things we believe. When men believed that the earth was flat, they were not credulous: they were using their common sense, and, if asked to prove that the earth was flat, would have said simply, Look at it. Those who refuse to believe that it is round are exercising a wholesome skepticism.”
—George Bernard Shaw (18561950)
“Married love is a stream that, after a certain length of time, sinks into the earth and flows underground. Something is there, but one does not know what. Only the vegetation shows that there is still water.”
—Gerald Branan (18941987)
“When he painted a road, the roadmakers were there in his imagination. When he painted the turned earth of a ploughed field, the gesture of the blade turning the earth was included in his own act. Wherever he looked he saw the labour of existence; and this labour, recognized as such, was what constituted reality for him.”
—John Berger (b. 1926)