The Moon Is Shrinking Giant cracks in surface show moon's contraction: scientists By Nick McMaster, Newser Staff Posted Aug 20, 2010 1:04 PM CDT 20 comments Comments A bird soars in front of a half moon near Glencoe, Ky., Monday, Aug. 16, 2010. (AP Photo/Ed Reinke) (Newser) – The moon is getting smaller, its surface cracking as it slowly cools and shrinks, astronomers believe. A spacecraft found 14 new surface cracks, cluing them into the contraction. "One of the remarkable aspects of the lunar scarps is their apparent young age," a Smithsonian scientist tells the Daily Mail. That suggests the shrinking is a recent process, at least in geological terms: Best guess is that the moon's radius has shrunk by about 330 feet over the last 800 million years.