Hey, Sky Fans! Welcome back! Were you able to see the Lyrid meteors last week? I wasn’t; clouds.
Thinking about meteor showers got me thinking about the word meteor and how it’s a bit of a confusing one.
Let’s do this. It’s a three-fer this time!
We have three similar words to talk about today. Do you know the difference between a meteor, a meteoroid, and a meteorite? It can be confusing.
Along with all of the bigger things in the solar system, there’s also some smaller bits of things, space rocks, space pebbles, schmutz the size of sand or dust. This is leftover crud that didn’t stick to anything else, or maybe it was spat off by a comet, or, if you can believe it, it was kicked out into space after something smashed into Mars or the Moon (or other places). Thousands of tons of it meets up with the Earth each year.
Comets are amazing balls of rock and ice that travel around the sun in long, unusual, eccentric orbits. As they get closer to the Sun, the Sun heats the comet and cooks off some of the ice, which causes the comet to leave behind some of dirt, rocks and pebbles, this astroschmutz. When Earth, zooming along in its orbit, crosses this stuff, we see some of it shoot and dart across the sky heating up high overhead. If there’s a particularly thick pocket, we see a meteor shower. Most of these things are really tiny, but once in a while they’re big enough that only part will burn up, and a piece will make it all the way to the ground.
So, here we go:
A meteoroid is any of these bits that are smaller than about a meter across, they’re called meteoroids as they travel through space. Bigger than a meter, and we’re into asteroid territory.
When one of these meteoroids hits Earth’s atmosphere, it heats up very quickly from all of friction involved. We see its glow as a meteor, streaking across the sky. This is also called a shooting star. A really big, bright one, like the 20-meter asteroid that exploded over Chelyabinsk, Russia in 2013, is called a bolide.
If the meteor was big enough and part of it survived the tumult of entering the atmosphere, the piece that’s leftover and lands on your car, which you probably washed that afternoon, is called a meteorite.
Quickly: A meteoroid travels in space, a meteor travels in the atmosphere, and a meteorite has hit the ground. They’re all the same object, rocks and sand from space. It’s just the context that changes.
What always grabs me about meteors, though, isn’t the ones that come from comets. That seems like fairly direct, simple science. You’re walking along and have an armful of papers, but you’re also eating a banana, drinking coffee, juggling, and playing Asteroids (as comets do). Suddenly, you realize you don’t have any papers anymore, but there’s a trail of paper behind you showing you where you’ve been. Okay, fine.
Instead, there are times when a meteorite will hit the moon, Mars, or some other object. When it does, it kicks up more stuff. If the meteorite was big and powerful enough, that kicked-up stuff makes its way out into space. From there, these new meteoroids settle into their own orbits around the Sun and travel, alone and cold, for years and years, until, maybe, just maybe, they get close enough. They get pulled in by Earth’s gravity, streak across the sky, and maybe make it to the ground.
If you’ve ever doubted how connected everything is, here’s another example of it. I’m amazed every time there’s news of a geologist finding a piece of Mars here on Earth. It’s amazing that that rock made it all that way. I wonder how long it took, orbiting and orbiting until its orbit met Earth. It’s also amazing that there are people who’ve worked and learned so much about the structure of the solar system that they are able to tell that a particular rock among a whole bunch of other rocks is from Mars, or anywhere else. That alone is undeniably amazing.
The word meteor is the original of the three, the other two joined language later. It comes from a Greek word, by way of Latin, that means high or lofty. I’m sure you’ve heard the phrase “meteoric rise” and possibly wondered why something that’s typically thought of as falling being described as rising. The phrase is, maybe, more describing the height of the object, rather than the direction it’s moving.
So, there you have it. Does this clear things up? I hope so.
Now, let’s hope the clouds move out. Clear skies, everyone!