Signs of Late Volcanism Seen on Moon

olcanic activity on the far side of the moon may have lasted longer than previously thought, recent images from a Japanese lunar satellite suggest.

The finding, detailed in the Nov. 7 issue of the journal Science, could help shed light on the moon's formation and evolution.

Scientists think that the moon formed when a rogue planet about the size of Mars crashed into Earth and ripped out a chunk of the planet's molten mantle. Some of the material from that chunk began to orbit Earth, gradually cooling over millions of years to form the moon.

The lunar surface is dead now, but over the millions of intervening years since it formed, it experienced bouts of volcanic activity.

Scientists have studied lunar volcanic features, the most common of which are mare (dark "seas") basalts, from orbit to determine when they formed. Radiogenic dating is the best way to date mineral deposits, but samples from the moon's surface are limited, and come only from a few locations on the moon's nearside.

Another way to estimate the age of volcanic features is to count the number of impact craters they have: the younger the feature, the fewer the craters that mark its surface.

Source: http://news.yahoo.com/s/space/20081106/sc_space/signsoflatevolcanismseenonmoon;_ylt=Aj88A7s.nQ75skuj01_Q02ZxieAA