In this image provided by NASA Thursday June 16, 2011 shows Mercury forming a beautiful crescent shape in this image, acquired as the MESSENGER spacecraft was high above Mercury's southern hemisphere ... more 
In this image provided by NASA Thursday June 16, 2011 shows Mercury forming a beautiful crescent shape in this image, acquired as the MESSENGER spacecraft was high above Mercury's southern hemisphere on May 24, 2011. The spacecraft entered orbit around Mercury on March 18, 2011, becoming the first spacecraft ever to do so. (AP Photo/NASA) less 
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Associated Press | Photo By NASA
Fri, Jun 17, 2011 3:57 AM EDT