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No concrete evidence explains why there is a moon. The best hypothesis presented is the Giant Impactor hypothesis: It suggests that around 4.45 billion years ago, while the Earth was still forming, a large object hit the... More »

www.reference.com Science Astronomy Our Moon

A moon is a natural satellite consisting of solid material that naturally orbits a planet or dwarf planet. Although the Earth has just one moon, there are other planets that have more, and some that even have none. Moons... More »

www.reference.com Science Astronomy

A black moon describes either the second new moon of a calendar month, a calendar month without a new moon, a calendar month without a full moon, or the third new moon of a season that has four new moons. More »

www.reference.com Science Astronomy Our Moon
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There is evidence that the moon is seismically active, which means it can experience the moon version of an earthquake. During the 1969 and 1972 moon landings, astronauts placed seismometers on the moon in order to allow... More »

www.reference.com Science Astronomy Our Moon

As of October 2014, 12 people, all U.S. astronauts, have walked on the moon. The first man to step on the moon was Neil Armstrong, commander of Apollo 11, in July of 1969. The last was Eugene Cernen, commander of Apollo ... More »

www.reference.com Science Astronomy Our Moon

The moon is tidally locked with Earth, which has the effect of synchronizing its rotation period with the period of its orbit. Completing one "day" per orbit of the Earth, the moon has shown the same face to the Earth fo... More »

www.reference.com Science Astronomy Our Moon

The moon's rotation is the same as any other rotation, with the exception that one full rotation is completed in the same amount of time as one full orbit. This is a consequence of tidal coupling between the Earth and th... More »

www.reference.com Science Astronomy Our Moon