In The History of the Kings of Britain, medieval chronicler Geoffrey of Monmouth tells the story of how a shooting star foretold the death of Ambrosius and the coming of King Arthur. Long ago, shooting stars were commonly thought to be omens, prophecies, or messages from the gods. Today, we know shooting stars aren’t really omens; they’re not even stars. They’re meteors.
Why Do Meteors Glow?
When seen from Earth, a meteor looks like a star zooming across the sky in a blaze of white, so it’s natural to think that’s just what it is. But a meteor is actually something much less stellar. It’s a rock or a bit of sand or ice — space debris — that encounters Earth’s atmosphere. There’s lots of debris out there, and it’s moving incredibly fast, sometimes as fast as 100,000 miles per hour, says Cameron Hummels, a computational astrophysicist and research scientist at Caltech.
When a fragment of debris collides with Earth’s atmosphere, it compresses the atmosphere in front of it as it hurtles through, a phenomenon known as bow shock. Hummels, who is also Caltech’s director of astrophysics outreach, compares this to the way water piles up in front of a speedboat as it zooms along a lake or river.
