It was the blast felt around the world: when the Chelyabinsk meteor exploded over Russia in February, its shock wave was powerful enough to emit subsonic waves to far-flung regions across the planet.
Now, scientists know a little bit more about that mysterious space rock — which, at 12,000 tons, was the biggest meteor to explode over Earth in more than a century. In a new study published in this week’s Science, researchers led by the Russian Academy of Scientists relied on an unprecedented volume of information — courtesy of surveillance cameras, cell phones, seismic instruments, and eyewitness observations — to assemble heaps of data about the freaky incident. "Our goal," said study co-author Peter Jenniskens, "was to understand all circumstances that resulted in the damaging shock wave that sent over 1,200 people to hospitals in the Chelyabinsk Oblast area that day."
By watching various amateur video clips of the rock as it soared towards Earth, the team was able to determine key details, shown in the illustration below. Among them are the meteor’s precise trajectory, its speed upon entering the atmosphere, exactly where it fragmented into smaller pieces, and the point at which that explosion shone most powerfully. That moment — a searingly bright flash 30 times stronger than the sun — actually caused severe sunburns among some bystanders.
Shockwaves from the fireball, the team concluded, caused damage in areas up to 50 miles from the meteor’s trajectory on either side. Fortunately, the largest fragment from the explosion, a 1,250-pound meteorite, hit a frozen lake. The team was able to recover that piece, and their subsequent analysis reveals that the rock — a relatively ordinary "chondrite" space rock — was more than 4,400 million years old.
Now, experts hope that their analysis of the Chelyabinsk incident can help detect and track future space-based threats — and calculate the potential havoc they might wreak upon planet Earth. And it looks like they might be making more such calculations than previously anticipated: yet another new study, published this week in Nature, warns that the likelihood of events like Chelyabinsk is 10 times higher than experts had thought — making the phenomenon one we can expect every 25 years or so.