If humans ever set up camp on the moon, NASA thinks they can make great use of some natural shelter: moon caves. As Vice explains, the space agency has identified more than 200 lunar pits on the moon's surface, and those pits lead to caves below that range anywhere from 5 yards to 1,000 yards in diameter. It's not entirely clear how the caves formed, but NASA floats one hypothesis: Ancient lava flows created voids beneath the surface, and then nearby meteor strikes caused the roofs to cave in.
"Pits would be useful in a support role for human activity on the lunar surface," says Arizona State University's Robert Wagner, whose photo-scanning algorithm identified most of them, notes Universe Today. "A habitat placed in a pit—ideally several dozen meters back under an overhang—would provide a very safe location for astronauts: no radiation, no micrometeorites, possibly very little dust, and no wild day-night temperature swings." The next step is to drop a probe into one of holes to look around. Bonus: The research could shed light on how surface patterns such as the "man on the moon" formed. (Click to read about how the moon is older than we thought.)