NASA’s Mars Reconnaissance Orbiter snapped the pic below. It’s a cave skylight on the southeast most flank of the large Martian volcano, Pavonis Mons. That pit, NASA says, is about 180 meters wide.
CREDIT: NASA/JPL/University of Arizona
NASA scientists have been getting increasingly excited about cave exploration on Mars since they first theorized the existence of Mars cave skylights in 2007 using early images. Mars cave skylight spotting was such a craze that middle schoolers got into the act. They spotted one in 2010.