Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2007 February 9
See Explanation.  Clicking on the picture will download
 a GIF movie featuring the image.

Ptolemaeus, Alphonsus and Arzachel
Credit & Copyright: Alan Friedman

Explanation: These three ancient, large impact craters lie on the north eastern shores of Mare Nubium, the lunar Sea of Clouds. Along the top of the stark mosaic (left to right) are the namesakes of Ptolemaeus, Alphonsus and Arzachel. The picture offers a remarkably detailed view of the well-studied region with shadows emphasizing the large crater central peaks and slumping walls. Careful examination also reveals the 110 kilometer long Straight Wall, a fault 200-300 meters high, and the intriguing Davy crater chain. Overall, the striking moonscape is similar to the final images recorded by the Ranger 9 spacecraft, before it crashed into the 108 kilometer wide crater Alphonsus in March of 1965.

Tomorrow's picture: journey to the center

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