txtr: Mimas, photographed by Voyager 2, 13th November 1980.
(I checked; November 13th was a Thursday, not a Friday.)
Image credit: NASA/JPL.
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Luna by Michæl Paukner on Flickr.
Luna
A map of the chief plains and craters of the Earth’s Moon. The plains were originally supposed to be seas: hence the name “Mare.”
The Moon is about 238,857 miles (384,403 km) from Earth on average. At its closest approach (the lunar perigee) the moon is 221,460 miles (356,410 km) from the Earth. At its farthest approach (its apogee) the moon is 252,700 miles (406,700 km) from the Earth. The moon revolves around the Earth in about one month (27 days 8 hours). It rotates around its own axis in the same amount of time. The same side of the moon always faces the Earth; it is in a synchronous rotation with the Earth.
The Moon’s orbit is expanding over time as it slows down (the Earth is also slowing down as it loses energy). For example, a billion years ago, the Moon was much closer to the Earth (roughly 200,000 kilometers) and took only 20 days to orbit the Earth. Also, one Earth ‘day’ was about 18 hours long (instead of our 24 hour day). The tides on Earth were also much stronger since the moon was closer to the Earth.
Most scientists believe that the moon was formed from the ejected material after the Earth collided with a Mars-sized object. This ejected material coalesced into the moon that went into orbit around th Earth. This catastrophic collision occurred about 60 million years after Earth itself formed (about 4.3 billion years ago). This is determined by the radioisotope dating of moon rocks.
Wiki: en.wikipedia.org/wiki/Moon
Google Moon: www.google.com/moon
© Copyright 2009 Michael Paukner. All Rights Reserved.