One solitary boulder on the Moon apparently decided to take a little journey. The Lunar Reconnaissance Orbiter Camera captured the track of a bouncing, rolling 9-meter boulder that used to sit along the rim of a crater. From the pristine nature of the tracks, it might seem that the rock may have taken its trip just recently. But with the high resolution capability of the LROC, scientists can see that a few tiny craters are superimposed among the track and therefore post-date the time the boulder traveled. Scientists estimate this track was created 50-100 million years ago.
Though long ago to humans, however, this boulders journey was made in geologically recent times, wrote lunar scientist James Ashley on the LROC website. Studies suggest that regolith development from micrometeorite impacts will erase tracks like these over time intervals of tens of millions of years Eventually its track will be erased completely.
What might have caused the rock to roll so recently? Ashley said perhaps this boulder was sent on its way by ground-shaking caused by the violence of a nearby impact. Perhaps a direct hit by a small meteoroid did the job.
Explore further: Ceres bright spots sharpen but questions remain