To gather data on this volcano, these scientists must go inside... Watch them descend into Mt. Vesuvius' 1,000-foot-deep crater: | NOVA l PBS

Scientists were baffled by these enormous fossils of an ancient creature they called the Basilosaurus, or "king lizard." Then they discovered that Basilosaurus wasn't a lizard, but something else entirely... | NOVA l PBS

These fossils reveal that Antarctica was once covered in forests—and connected to South America. | NOVA l PBS