Meteors and Meteor Showers: The Science
By Robert Roy Britt
Imagine a baseball zipping along at 30,000 miles per hour. That's how big and fast many meteors are. And though some are bigger than baseballs, most are more like grains of sand. The larger meteors are sometimes broken bits off asteroids or other planets. The small stuff is often dust left by a passing comet.
Entry into the atmosphere
When they plow through the atmosphere, meteors are heated to more than 3000 degrees Fahrenheit, and they glow. Meteors are not heated by friction, as is commonly thought. A phenomenon called ram pressure is at work. A meteor compresses air in front of it. The air heats up, in turn heating the meteor.
The intense heat vaporizes most meteors, creating what we call shooting stars. (Most become visible at around 60 miles up.) Some large meteors splatter, causing a brighter flash called a fireball, and an explosion, which can often be heard up to 30 miles away. When meteors hit the ground, they're called meteorites. Some meteors are bits broken off asteroids, others -- mere cosmic dust -- are cast off by comets. (And one more term: A meteoroid is an object in space that may, if it enters our atmosphere, become a meteor.)
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