<p>The sliver of a crescent moon seems to dip into Earth's atmosphere in a picture taken by NASA astronaut <a href="http://www.jsc.nasa.gov/Bios/htmlbios/garan-rj.html">Ron Garan</a> from the International Space Station on July 31. The station completes an orbit of Earth every 90 minutes, so astronauts can see the moon set about 16 times a day.</p><p>(Related: <a href="http://news.nationalgeographic.com/news/2011/08/110803-earth-two-moons-collision-space-science/">"Earth Had Two Moons, New Model Suggests."</a>)</p>
Lunar "Grin"
The sliver of a crescent moon seems to dip into Earth's atmosphere in a picture taken by NASA astronaut Ron Garan from the International Space Station on July 31. The station completes an orbit of Earth every 90 minutes, so astronauts can see the moon set about 16 times a day.
(Related: "Earth Had Two Moons, New Model Suggests.")
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