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Earth

Asteroids and artificial satellites
Earth has at least five co-orbital asteroids, including 3753 Cruithne and 2002 AA29. A trojan asteroid companion, 2010 TK7, is librating around the leading Lagrange triangular point, L4, of Earth in E ...
2014-2-21 23:04
Moon
he Moon is a relatively large, terrestrial, planet-like satellite, with a diameter about one-quarter of the Earth's. It is the largest moon in the Solar System relative to the size of its planet, alth ...
2014-2-21 23:03
Predicted future
Estimates on how much longer the planet will be able to continue to support life range from 500 million years (myr), to as long as 2.3 billion years (byr). The future of the planet is closely tied to ...
2014-2-21 23:03
Geological history
Earth's atmosphere and oceans formed by volcanic activity and outgassing that included water vapor. The origin of the world's oceans was condensation augmented by water and ice delivered by asteroids, ...
2014-2-21 23:03
Formation
The earliest material found in the Solar System is dated to 4.5672±0.0006 bya; therefore, it is inferred that the Earth must have been formed by accretion around this time. By 4.54±0.04 bya the prim ...
2014-2-21 23:02
Cultural and historical viewpoint
The standard astronomical symbol of the Earth consists of a cross circumscribed by a circle.Unlike the rest of the planets in the Solar System, humankind did not begin to view the Earth as a moving ob ...
2014-2-21 23:02
Human geography
Cartography, the study and practice of map making, and vicariously geography, have historically been the disciplines devoted to depicting the Earth. Surveying, the determination of locations and dista ...
2014-2-21 23:02
Natural and environmental hazards
Large areas of the Earth's surface are subject to extreme weather such as tropical cyclones, hurricanes, or typhoons that dominate life in those areas. From 1980 to 2000, these events caused an averag ...
2014-2-21 23:01
Natural resources and land use
The Earth provides resources that are exploitable by humans for useful purposes. Some of these are non-renewable resources, such as mineral fuels, that are difficult to replenish on a short time scale ...
2014-2-21 23:01
Evolution of life
Highly energetic chemistry is thought to have produced a self-replicating molecule around 4 bya and half a billion years later the last common ancestor of all life existed. The development of photosyn ...
2014-2-21 23:01
Biosphere
A planet's life forms are sometimes said to form a "biosphere". The Earth's biosphere is generally believed to have begun evolving about 3.5 bya. The biosphere is divided into a number of biomes, inha ...
2014-2-21 23:00
Habitability
A planet that can sustain life is termed habitable, even if life did not originate there. The Earth provides liquid water—an environment where complex organic molecules can assemble and interact, and ...
2014-2-21 23:00
Axial tilt and seasons
Due to the axial tilt of the Earth, the amount of sunlight reaching any given point on the surface varies over the course of the year. This causes seasonal change in climate, with summer in the northe ...
2014-2-21 23:00
Orbit
Earth orbits the Sun at an average distance of about 150 million kilometers every 365.2564 mean solar days, or one sidereal year. From Earth, this gives an apparent movement of the Sun eastward with r ...
2014-2-21 22:59
Rotation
Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025 SI seconds). As the Earth's solar day is now slightly longer than it was during the 1 ...
2014-2-21 22:59
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