If you are anything like me, you probably like watching for shooting stars in the night sky. A shooting star, or a meteor, is usually a small rock that falls into Earth’s atmosphere.
When I went to visit my friend Michael Allen, a senior instructor of astronomy and physics at Washington State University, he told me a lot of shooting stars are no bigger than a pencil eraser.
“The earth is going to pass a random pebble once in a while and that will make a streak in the sky,” he said.
You might be wondering how such a small rock can create such a bright streak of light. If you’ve ever rubbed your hands together, you may know that friction is what helps them warm up.
When a small rock is falling into Earth’s atmosphere, it falls super-fast. Depending on the meteor, it can travel anywhere from 36,000 feet to 236,220 feet in a single second. As it falls, there is a lot of friction between the air and the rock. With all that friction, the rock starts to get really hot.
It is this friction that will help melt part of the rock. If the rock is small enough, it will evaporate, leaving behind a trail of hot gasses—and that’s the shooting star that you see streaking across the night sky.