October 16, 2009--Marked with a red circle, a pale plume rises from the moon's Cabeus crater in a composite image taken by NASA's LCROSS spacecraft on October 9. LCROSS, which stands for Lunar Crater Observation and Sensing Satellite, sent an empty rocket crashing into the moon in a search for water ice, which is presumed to be hiding inside permanently shadowed craters.

Although the impact was anticipated to stir up enough material to be seen from Earth, the plume was largely invisible to ground-based telescopes. But images collected from LCROSS later proved that a plume was created, and that it swelled to 3.7 to 4.9 miles (6 to 8 kilometers) wide 15 seconds after impact.