Episodes

If things had worked out differently, you might see a tiny pterodactyl on your windowsill instead of a modern bird. That’s because pterosaurs evolved more than 80 million years before the earliest birds, with many of the same characteristics. Pterosaurs had hollow bones, some with an even more sophisticated structure than birds; it’s one of the things that allowed them to grow to such immense size: the largest pterosaur was bigger than an F-16 fighter jet, with a wingspan of 33 ft. These giganti...

Here’s a riddle: If heat rises, and mountains are closer to the sun, why are they always colder? The answer may surprise you. The heat of the sun can’t actually radiate through space. There would need to be particles of some element to conduct its heat; but space is a vacuum. Instead, the sun emits electromagnetic energy: ultraviolet, visible and infrared light, X-rays, and radio waves. When this solar radiation finally meets Earth’s surface, it warms it. And that radiates heat back upward, warm...