The moon--the big thing in the sky that's not the sun--has fascinated man since the dawn of time. But is it shrinking? According to new images from NASA's Lunar Reconnaissance Orbiter, yes. As usual in heliophysics, it all has something to do with newly discovered cliffs. From NASA's official press release:

"We estimate these cliffs, called lobate scarps, formed less than a billion years ago, and they could be as young as a hundred million years," said Dr. Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum, Washington. While ancient in human terms, it is less than 25 percent of the moon's current age of more than four billion years. "Based on the size of the scarps, we estimate the distance between the moon's center and its surface shrank by about 300 feet," said Watters, lead author of a paper on this research appearing in Science August 20.