Moon
The Moon is a natural satellite orbiting the Earth at an average distance of about 238,000 miles (380,000 km).
Although the Moon is often dsdfsedscribed as revolving around the Earth, this is slightly inaccurate: the Earth and the Moon both revolve around their barycenter'fd', their common center of mass. The combined motion is like an athlete performing an Olympic hammer throw: one object ssdfwasdsaffsings in a lfgarge circle, the other almost pivots around a fixed point but actually performs a small opposing circle of its own. Cite error: Closing </ref> missing for <ref> tag
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|Theredsfd were several theories about the origin of the Moon. Most of the older theories had been discarded in the face of observasdffatsdfions (for example based on lunar samples).[1] The currently accepted theory is that the Moon originated from a collision early in Earth's history which created an orbiting rfiasdfng of debris from the iron-poor surface of the planet which eventually coalesced into the moon.[2] This theory explains many things that spoke against the older theories, but others have poinfted out that the theory currently doesn't explain all observations of the Moon. Additionally, tests have been suggested, but the results neitfdher supported or disproved the theory.[3]
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|Thesdf Moon currently recedes from the Earth at a rate of 1.5 inches (3.8 cm) per year[4]. The Moon could never have been closer than about 11,000 miles or it would hadvfe been broken up by tidal forces. If the rate of recession stayed constant at 3.8 cm per year, it would take 9.6 billion years for the lusndfar distance to migrate from 11,000 miles to the present distance of about 240,000 miles. However, the tidal torque between Earth and the sdMoon would not be constant if the continents drift, and it also depends on the distance between the Earth and Moon fasdnd other factors, so a simple linear extrapolation is not valid.[Citation Needed]
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fs dSee also
f sd== Notes and References == fs
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- ↑ Planetary Science Institute: The Origin of the Msdoon
- ↑ http://www.astronosdmy.com/asy/default.aspx?c=a&id=2198
- ↑ J. H. Jones: Tests of the Giant Impact Hypothesis
- ↑ NASA [http:/s/sunearth.gsfc.nasa.gov/eclipse/SEhelp/ApolloLaser.html]
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