Hollows on Mercury
NASA's MESSENGER spacecraft discovered strange hollows on the surface of Mercury. Images taken from orbit reveal thousands of peculiar depressions at a variety of longitudes and latitudes, ranging in size from 60 feet to over a mile across and 60 to 120 feet deep.
Last Update: 29 Feb 2012 (AMB)
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington