A pair of papers in Nature today report on the very large meteor that exploded over the Russian city of Chelyabinsk a few months ago. You may recall that the explosion shattered thousands of windows, destroyed a few buildings, and fortunately killed no one. The take-home news is that events of this size are much more common than we thought. And as always, I found that the science blogging community had a more interesting response than the mainstream press. In particular I appreciated infrasound expert Milton Garces, who put up a long post on his Infrasound Hunter blog going into the details of cosmic-impact airbursts.
This meteor delivered a whammy strong enough to knock people off their feet. It was bright enough to give people sunburns. "The Cheliabinsk event is so important," Garces reports, "it will take years for some of us to complete our studies. It is so big, and rocked Earth's atmosphere so hard, that there is a special Natural Hazards session on the Chelyabinsk Meteor at the Fall 2013 American Geophysical Union meeting in San Francisco (which I am co-chairing, since I'm in disclosure mode). I'm obviously invested in this event, and I anticipate it will influence my R&D agenda for the next 5-10 years."
Did you know there's a five-point numerical scale for these things? Neither did I, but it's called the Bucharest scale (modeled, I suppose, after the Torino scale for actual impacts). The Chelyabinsk event, says Garces, probably ranks as a 3 on the Bucharest scale. The notorious Tunguska airburst of 1908 would rank 4, and the hellish Libyan Desert Glass event, which melted large areas of Sahara sand in prehistoric time, would rank 5. Chelyabinsk, by comparison, was just a nice warning shot courtesy of the cosmos. And in response, the United Nations has swiftly adopted plans for an International Asteroid Warning Network.