Yesterday a ten-ton meteor exploded above the Urals in Russia, injuring at least a thousand people, shattering windows, and even buildings.
Tonight scientists say that an asteroid missed crashing into Earth several hours ago by a mere 17,000 miles, eerily close by standards of spatial distances.
But what’s the difference between an asteroid that misses Earth and a meteor that comes crashing down? And as long as we’re on the subject, is there a difference between an asteroid and a comet? or between a meteor and meteorite? or a meteoroid?
The differences are not always clear-cut because their identities often change, so that an asteroid might not remain an asteroid, or a meteor might become a meteorite. I know these questions do not qualify among the great epistemological questions of the age, but here are the current definitions. It helps organize one small corner of chaos anyway.
An asteroid in basically a planetoid made of rock and basic metals that orbits the Sun in the same way that Earth and the other planets revolve around the Sun.
A comet is different from an asteroid in that it is composed of dirt and ice. When they are close to the Sun, it is possible to see a comet’s tail of dust and gas. Apart from that, a comet is pretty much like an asteroid, and it is sometimes hard to tell which is which.
A meteoroid is a small chunk from an asteroid or comet. They also have their orbits around the Sun but are too small to be asteroids or comets.
A meteor is a shooting star. It’s a meteoroid that enters the atmosphere of another object – like Earth – and streaks through the sky as it burns up in the atmosphere of a planet like Earth.
A meteorite is a meteoroid that survives its passage through Earth’s atmosphere and impacts an object like Earth. They are the ones that create the most damage to life on Earth. Historically, meteor strikes may have been responsible for some of the 54 major extinctions we know have taken place in the last 550 million years. The dinosaurs may have been felled by the catastrophic destruction caused by a meteor strike.
Well you never know. This is information that might be useful one day.
But come to think of it, I hope not any time soon anyway.