Ah, meteor showers. A warm summer night. Blanket on the grass. A sky full of stars. Look, there’s one! Perhaps a quick streak of light through a corner of the sky – blink and you’ll miss it. Or maybe it’s a big one, a blazing fireball that almost seems to scream from one horizon to another. And another one! And another one! You could spend hours here, gazing up at the heavens that seem so active and alive.
You’re basically getting pooped on by a comet.
Those meteors are tiny bits of space debris slamming into the Earth’s atmosphere at tens of thousands of miles per hour. The tiniest ones are no bigger than a measly grain of sand, while the big ones (making the ooh-and-ah-worthy lightshows) are…slightly larger than a rain of sand. But when you’re cruising at Mach 20 even a grain of sand can pack a healthy wallop.
In space these bits of junk are called meteorites. When they slam through our air they’re called meteors. When (and if) they hit the ground, we call them meteoroids. None of this naming convention makes any sense, but that’s the way the rules are.
Anyway, back to comet poop.
When comets orbit the sun, sometimes they get a little too close for comfort. They’re made of mostly ices (like water ice and ammonia ice) with some chunks of dirt stuck in there to make them look ugly. They’re not very big, so they’re only loosely held together. Out in the frozen depths of the solar system this is no big deal, but near the intense heat of the sun the comets basically lose it.
This makes for a very pretty comet tail that we get to enjoy, but it also means that bits of the comet get strewn all over its orbit as it passes through the inner suburbs of the solar system.
And sometimes the Earth goes swimming through all that debris, and we get a meteor shower.