Earth
hideEarth is the third planet from the Sun, and the largest of the terrestrial planets in the Solar System in terms of diameter, mass and density. It is also referred to as the World, the Blue Planet, and Terra.
Home to millions of species, including humans, Earth is the only place in the universe where life is known to exist. The planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land. The physical properties of the Earth, as well as its geological history and orbit, allowed life to persist during this period. The world is expected to continue supporting life for another 1.5 billion years, after which the rising luminosity of the Sun will eliminate the biosphere.
Earth's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.
Earth interacts with other objects in outer space, including the Sun and the Moon. At present, Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis. This length of time is a sidereal year, which is equal to 365.26 solar days. The Earth's axis of rotation is tilted 23.4° away from the perpendicular to its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days). Earth's only known natural satellite, the Moon, which began orbiting it about 4.53 billion years ago, provides ocean tides, stabilizes the axial tilt and gradually slows the planet's rotation. Between approximately 4.1 and 3.8 billion years ago, asteroid impacts during the Late Heavy Bombardment caused significant changes to the surface environment.
Both the mineral resources of the planet, as well as the products of the biosphere, contribute resources that are used to support a global human population. The inhabitants are grouped into about 200 independent sovereign states, which interact through diplomacy, travel, trade and military action. Human cultures have developed many views of the planet, including personification as a deity, a belief in a flat Earth or in Earth being the center of the universe, and a modern perspective of the world as an integrated environment that requires stewardship.
For more information about Earth, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with earth
Scientist uncovers relics of ancient cosmos
Space & Earth / Space Exploration
18 hours ago |
4.4 / 5 (13) |
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(PhysOrg.com) -- A University of Manchester scientist, working as part of an international team, has uncovered an unexpectedly rich trove of relicts from the ancient cosmos.
California's troubled waters: Satellite-based findings reveal major groundwater loss in Central Valley (w/ Video)
Space & Earth / Earth Sciences
20 hours ago |
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New space observations reveal that since October 2003, the aquifers for California's primary agricultural region - the Central Valley - and its major mountain water source - the Sierra Nevada - have lost nearly ...
Earth's atmosphere came from outer space, find scientists
Space & Earth / Earth Sciences
Dec 10, 2009 |
4.2 / 5 (29) |
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(PhysOrg.com) -- The gases which formed the Earth's atmosphere - and probably its oceans - did not come from inside the Earth but from outer space, according to a study by University of Manchester and University ...
Life on Mars theory boosted by new methane study
Space & Earth / Space Exploration
Dec 08, 2009 |
4.9 / 5 (30) |
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Scientists have ruled out the possibility that methane is delivered to Mars by meteorites, raising fresh hopes that the gas might be generated by life on the red planet, in research published tomorrow in Earth an ...
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TRMM sees 05B winding down off the Sri Lanka coast
Space & Earth / Earth Sciences
14 hours ago |
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Tropical Depression 05B is dissipating on the east coast of Sri Lanka today and over the next couple of days, but not before bringing some moderate and heavy rain over the next couple of days to some areas ...
Queen Mary scientists shed light on a mysterious particle
16 hours ago |
5 / 5 (1) |
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(PhysOrg.com) -- Physicists at Queen Mary, University of London have begun looking deep into the Earth to study some of nature's weirdest particles; neutrinos.
Nearly 100 new species described by California Academy of Sciences in 2009
17 hours ago |
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In 2009, researchers at the California Academy of Sciences added 94 new relatives to our family tree. The new species include 65 arthropods, 14 plants, eight fishes, five sea slugs, one coral, and one fossil ...
Fossils on the Edge of Forever
Space & Earth / Earth Sciences
17 hours ago |
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Astrobiologists have not yet found alien life on other planets. But the fossil record has evidence of aliens of another sort: the Ediacarans that lived on Earth millions of years ago.
Magnetic Dance of Titan and Saturn To Be Main Attraction during Flyby
Space & Earth / Space Exploration
17 hours ago |
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(PhysOrg.com) -- When it flies by Saturn's largest moon, Titan, this weekend, NASA's Cassini spacecraft will study the interactions between the magnetic field of Saturn and Titan. The flyby will take place ...
NASA Launches Web Site for Teenagers That Want More Class
Space & Earth / Space Exploration
17 hours ago |
3.5 / 5 (2) |
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(PhysOrg.com) -- NASA has launched a new Web site created specifically for teenagers that provides teens access to current NASA spacecraft data for use in school science projects, allows them to conduct real experiments with ...
Studying ice crystals to understand the cloud-climate connection
Space & Earth / Earth Sciences
18 hours ago |
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(PhysOrg.com) -- Beginning in mid-December, scientists will undertake a special mission to squeeze the secrets out of ice crystals in cirrus clouds. The SPARTICUS, or Small Particles in Cirrus, campaign will ...
'Rock-breathing' bacteria could generate electricity and clean up oil spills
18 hours ago |
3.2 / 5 (6) |
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A discovery by scientists at the University of East Anglia (UEA) could contribute to the development of systems that use domestic or agricultural waste to generate clean electricity.
The mammoths' swan song revised
Other Sciences / Archaeology & Fossils
20 hours ago |
4.4 / 5 (10) |
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This is shown by samples of ancient DNA, analysed by an international team of research scientists under the leadership of Professor Eske Willerslev from Copenhagen University. Analyses of ancient DNA thereby ...
Global warming could significantly impact US wine and corn production, scientists say
20 hours ago |
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When it comes to nature, timing is everything. Spring flowers depend on birds and insects for pollination. But if spring-like weather arrives earlier than usual, and flowers bloom and wither before the pollinators appear, ...
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