When a meteor creates a sonic boom big enough to shatter windows and injure hundreds of people, it might feel like a portent of end times. Thankfully, it didn’t happen in December 2012, or we might be seeing panic now. Even so, it seems like a good idea to separate fact from fiction, and settle some common misconceptions.
This morning, a chunk of rock about 10 tons in mass entered Earth’s atmosphere at several times the speed of sound and exploded about 30 kilometers above Chelyabinsk, a city in the Ural region in Russia. According to the New York Times, at least one fragment of the meteor hit Earth (more on that in a moment), but the impact wasn’t big enough to create a huge crater like some other events in the past. For more information and lots of videos, see the coverage in Bad Astronomy, Life Unbounded, and Ars Technica.
Now, what about all the wilder stories flying around?
- You might have heard about the asteroid 2012 DA14, which will make a near pass to Earth today. The meteor in Russia is a completely unrelated object! The asteroid will be mostly visible in the southern hemisphere, while the meteor entered the atmosphere pretty far north. Based on what I’ve read, it appears the objects’ approach to Earth is in completely opposite directions as well. 2012 DA14 is a much bigger body, about 46 meters (150 feet) across.
- The video of a flaming crater that’s making the rounds is years old, and despite the English captions doesn’t describe a meteor impact at all. It’s actually a pit in Turkmenistan that’s been burning for years.
- Various reports have discussed a “meteor shower”. This rock was a single meteor, a general term describing anything burning in Earth’s atmosphere. Meteor showers (such as the famous Leonid, Perseid, and Orionid showers) are usually debris from comets’ tails, and consist of many tiny fragments. The Russian meteor was a big rock, albeit smaller than the impressive objects that produced the Tunguska event of 1908 in Siberia or the Meteor Crater in Arizona. If any fragment hits the ground, it’s called a meteorite. Thus, the fireball in the sky is properly called a meteor.
- Also, despite how it might seem between the Russian meteor and the Tunguska event, Russia isn’t specially cursed by meteor problems. I’ve gotten conflicting statistics on this, but it seems Earth gets a dramatic meteor like this about once a month. However, Earth is a big place, and if a similar meteor came in over the ocean or lightly-inhabited regions, it would make a big boom and have little other effect. In other words, these things happen a lot, and most of us don’t notice! This meteor is a bigger deal because it happened over a city, and thanks to Russia’s peculiar habit of dashboard video cameras, we have a lot of video footage. (Tip of the Pendulum to Steve Silberman for that find.)
- Update: Geert Berentsen just posted an excellent piece about the frequency of significant meteor impacts. The gist: it’s hard to be completely certain, but my rough guess (one every month or so) wasn’t far off. (Thanks to Ryan Hamilton for this link.)
For me, the takeaway message from the Russian meteor—and asteroid 2012 DA14—is that we need to do better at looking for dangerous meteors and asteroids. Astronomers (both professional and amateur) have identified nearly all of the biggest near-Earth objects (NEOs): the ones that, in the unlikely event they impact Earth, could cause mass extinctions like the one that probably wiped out the dinosaurs. However, the smaller rocks—called either asteroids or meteoroids—are harder to spot and to track.
I wouldn’t say we’re lucky, with regard to the Chelyabinskian meteor or 2012 DA14. Earth gets hit by meteors all the time! However, even a relatively small rock such as the Russian meteor injured hundreds of people, simply by exploding high above a city. It doesn’t take a huge asteroid to do a lot of damage, so we need to be more vigilant in our efforts to identify these smaller rocks too: track them and (if possible) prevent them from hitting Earth.
To this end, a private organization known as the B612 Foundation has made it a goal to look for potentially dangerous asteroids. I applaud that goal, yet I can’t help but feel that it should be a higher priority for governments. If we can put so much money into killing and spying on each other, couldn’t we devote a little more money to saving each other?
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