For years, fish fossils have turned up in the deserts of western Egypt, and nobody could explain why. Now we know: Long ago, the Egyptian desert was home to a body of water the size of Lake Michigan.
1800 miles underground lies a mysterious zone between the Earth's mantle and core. Nobody is quite sure what's down there, but new evidence suggests the area reaches temperatures of 7000 degrees Fahrenheit, meaning it could be a vast magma ocean.
The North and South magnetic poles swap places every 300,000 years, in a process that takes as much as 5,000 years. But evidence from an ancient lava flow suggests the poles were once moving 53 degrees per year.
The theory that a giant asteroid impact killed the dinosaurs 65 million years ago gained acceptance when we discovered the gigantic Chicxulub crater. Now we've found the crater of another asteroid that struck Earth at almost the exact same time.
Why are two groups of tiny sea creatures called bryozoans nearly identical, despite being separated by 1,500 miles of ice? They must have traveled across the continent long ago - on a massive Antarctic seaway.
Earth formed 4.54 billion years ago. But we've never found any rocks remaining from the time when our planet formed. Until now. A piece of ancient mantle is revealing Earth's oldest secrets.