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The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
The Phases of the Moon.
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How Do the Phases Get Their Names?

When the Moon appears smaller than a quarter, we call it a crescent. When the Moon appears larger than a quarter, we call it gibbous. When the moon is getting bigger (phases New to Full) it is waxing. When it is getting smaller (phases Full to New) it is waning.

For example, if today the Moon were a waxing crescent, then we would only see a little piece of the half of the Moon that is reflecting sunlight. But tomorrow, that piece would be bigger. If today the Moon were a waning gibbous, then we would see a big piece of the half of the Moon that is reflecting sunlight. But tomorrow, that piece would be smaller.

There is an easy way to tell if a crescent Moon is growing or shrinking. If the crescent Moon looks like a "C" (C for collapsing!), it is shrinking.

Last modified October 19, 2005 by Randy Russell.

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The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

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