Related topics: nasa , international space station , moon , atmosphere , planets
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
Titan's lakes could be explored by boat
Space & Earth / Space Exploration
Dec 22, 2009 |
4.6 / 5 (9) |
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(PhysOrg.com) -- If a suggestion to be made to NASA comes to fruition, vast lakes thought to be filled with liquid hydrocarbons near the north pole of Saturn's moon Titan, may one day be explored by boat.
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Astronomers discover 'tilted planets'
Dec 22, 2009 |
4.6 / 5 (15) |
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(PhysOrg.com) -- University of Exeter, UK, research has added to a growing evidence that several giant planets have orbits so tilted that their orbits can be perpendicular or even backwards relative to their ...
Shallow Origins
Space & Earth / Earth Sciences
Dec 22, 2009 |
5 / 5 (9) |
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In finding answers to the mystery of the origin of life, scientists may not have to dig too deep. New research is shedding light on shallower waters as a possible location for where life on Earth began.
Keck Telescopes Take Deeper Look at Planetary Nurseries
14 hours ago |
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(PhysOrg.com) -- Astronomers using the W. M. Keck Observatory have peered far into a young planetary system, giving an unprecedented view of dust and gas that might eventually form planets similar to Jupiter, ...
Researcher explains mystery of golden ratio
Dec 21, 2009 |
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The Egyptians supposedly used it to guide the construction the Pyramids. The architecture of ancient Athens is thought to have been based on it. Fictional Harvard symbologist Robert Langdon tried to unravel ...
Astronauts dock at International Space Station
Space & Earth / Space Exploration
Dec 22, 2009 |
5 / 5 (1) |
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A Russian rocket carrying three astronauts from Japan, Russia and the United States docked at the International Space Station Wednesday, the Russian flight control centre said.
Sun and moon trigger deep tremors on San Andreas Fault
Space & Earth / Earth Sciences
17 hours ago |
4.5 / 5 (2) |
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The faint tug of the sun and moon on the San Andreas Fault stimulates tremors deep underground, suggesting that the rock 15 miles below is lubricated with highly pressurized water that allows the rock to slip with little ...
Brown dwarf pair mystifies astronomers
Dec 21, 2009 |
4.8 / 5 (16) |
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(PhysOrg.com) -- Two brown dwarf-sized objects orbiting a giant old star show that planets may assemble around stars more quickly and efficiently than anyone thought possible, according to an international ...
Formation of the Gulf of Corinth rift, Greece
Space & Earth / Earth Sciences
Dec 22, 2009 |
4 / 5 (1) |
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A study of the structure and evolution of the Gulf of Corinth rift in central Greece will increase scientific understanding of rifted margin development and the tectonic mechanisms underlying seafloor spreading ...
Volcanic Quakes Help Forecast Eruptions
Space & Earth / Earth Sciences
Dec 22, 2009 |
2 / 5 (4) |
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Monitoring the earthquakes caused from magma movements inside an active volcano could help to improve the accuracy of forecasting an eruption.
Final launch of Ariane 5 GS completes busy year
Space & Earth / Space Exploration
Dec 21, 2009 |
5 / 5 (1) |
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(PhysOrg.com) -- Last week, an Ariane 5 GS launcher lifted off from Europe’s Spaceport in French Guiana on a journey to place the French military reconnaissance satellite Helios-2B into Sun-synchronous polar ...
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