You've probably seen the mysterious giant hole that was discovered in Siberia, which appears to lead into a large cave. We don't know its origin yet, but it isn't the only hole like that on Earth. Or the Moon: NASA found these formations there too, which are perfect for future human outposts. Or current alien/Nazi UFO bases.


Here are some high resolution images of the lunar pits. NASA estimates that there are over two hundred pits on the Moon's surface. These shouldn't be confused with the millions of craters on the Moon's surface though because they're something different. The pits range from sizes of about 16 feet to 3000 feet and get even wider underground. NASA explains how they form:


It's pretty impressive how much of a perfect circle some of them are.
