Talk:Earth/rewrite
From Wikipedia, the free encyclopedia
Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. It is the largest of the solar system's terrestrial planets, and the only planetary body that modern science confirms as harboring life. The planet formed around 4.57 billion (4.57×109) years ago, and shortly thereafter (4.533 billion years ago) acquired its single natural satellite, the Moon.
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The Blue Marble, taken from Apollo 17 | |
Physical characteristics | |
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Mean diameter | 12,742.02 km |
Equatorial circumference | 40,075 km |
Surface area | 510,067,420 km² |
- land | 148,847,000 km² (29.2 %) |
- water | 361,220,420 km² (70.8 %) |
Volume | 1.0832×1012 km³ |
Mass | 5.9736×1024 kg |
Density | 5,515 kg/m³ |
Its astronomical symbol consists of a circled cross, representing a meridian and the equator; a variant puts the cross atop the circle (Unicode: ⊕ or ♁). Besides words derived from Terra, such as terrestrial, terms that refer to the Earth include tellur- (telluric, tellurian, from the Roman goddess Tellus) and geo- (geocentric, geothermal (from the Greek goddess Gaia).