Researchers have found evidence for a substantial underground cave on the moon that is accessible from the surface, making the spot a prime location to build a future lunar base.
The cave appears to be reachable from an open pit in the Mare Tranquillitatis (Sea of Tranquility), the ancient lava plain where the Apollo 11 astronauts Neil Armstrong and Buzz Aldrin first set foot on the moon more than half a century ago.
