A meteor burned up above the skies of central Russia this morning, resulting in an aerial explosion and shockwave whose effects injured hundreds near Chelyabinsk. It brings to mind these lines from Samuel Taylor Coleridge’s The Rime of the Ancient Mariner:
The upper air burst into life!
And a hundred fire-flags sheen
To and fro they were hurried about!
And to and fro, and in and out,
The wan stars danced between
Events like this are not rare in Earth’s atmosphere, happening at least once per decade. What made this one special was its chance occurrence over a populated area and the fact that so many Russians have cameras running on their dashboards, like, all the time. Central Russia is no stranger to extreme aerial explosions due to space debris entering the atmosphere, most famously with 1908’s Tunguska Event, a several megaton aerial explosion of a comet fragment that knocked down 80 million trees.
Details about today’s meteor event are a little fuzzy, but I plugged some data into Purdue’s Impact Earth! meteor event calculator (which is a super fun way to pretend you’re destroying Earth) to see if I could nail down the energy released by this fireball.
From the videos I’ve seen, it looks like this thing entered the atmosphere at a pretty shallow angle, maybe 15 degrees from the horizon. It would have to be pretty dense rock in order to make it that far into the atmosphere without disintegrating, so I plugged its density in as 3,000-5,000 kg/m3. Russian officials reported its aerial velocity at about 15 km/second and that it was about the size of a dinner table, so 4 meters across? If you tweak the velocity, density, size and angle a little, you get an airburst of between 2 and 5 kilotons of TNT, or a little less than half the strength of the atomic bomb that exploded over Hiroshima, and an explosion altitude upwards of 50,000 feet.
Seems like a pretty accurate calculation, although the actual altitude must have been more like 30,000 feet to produce the shockwave that resulted in all the injuries. Play around with the Impact Earth calculator and let me know if you get anything better!
Although asteroid 2013 DA14 is making a close flight by Earth today, zipping inside of some of our satellites, but this meteor event almost certainly had nothing to do with that. Space is full of stuff, and every so often we are reminded of that in spectacular fashion.
BONUS: This kind of thing happens all over the solar system. Check out this scorched explosion remnant on Mars!
(GIF via amalucky)
Just to clarify, the asteroid skimming through our little circle of space is named 2012 DA14. There’s no danger of it hitting us, but a small one that it could hit one of our geosynchronous satellites.
We’re not sure exactly what its composition is, but if it were to impact it would probably be similar to the Barringa impact in Arizona and a bit bigger than the mentioned Tunguska event.
The Chelyabinsk meteorite (we add the -ite after a meteor survives our atmosphere and makes an impact) is estimated to be about 4m - DA14 is closer to 50m. And NASA estimates that up to 500,000 objects of that size cross Earth’s orbit, of which we are aware of maybe 1 or 2 percent.
As both of these asteroids indicate, we don’t know nearly as much about what is out there and potentially dangerous to us. Jeffrey Kluger of Time sums it up: