Today’s astronomy/science/geek blogs are talking about nothing but the meteor that exploded over Russia yesterday. This has to be the most well-documented meteor explosion in human history, with gazillions of photos and videos thrown up on the Internet almost immediately afterwards.
There’s little I can say that hasn’t been said better and more thoroughly elsewhere. I’d recommend reading Phil Plait’s two posts on it, here and here. In the second, updating post, Plait posts a photo of what is quite probably an impact hole in the ice over Chebarkul Lake made by one fragment of the exploding rock. He also notes that his initial impression of the booms heard in various videos — that they were merely sonic booms caused by the shock wave — was wrong:
After looking through more footage, it’s become clear that the multiple booms heard were in fact explosions, and not just shock waves from the meteoroid’s passing through the air. In some videos, you can see multiple flashes of light inside the contrail, which are clearly from the rock breaking up and then burning up very rapidly and with intense energy—the very definition of an explosion. Over the course of just a couple of seconds, the large energy of motion of the meteoroid was converted into heat, and this exploded with a yield of several thousand tons of TNT. It goes to show that you need not have an asteroid hit the ground to be dangerous, and in fact the hole in the ice made by the plummeting meteoroid was probably the gentlest thing it did.
While Plait states that estimating the size is hard right now because the information is too scattered, the science magazine Nature is one step ahead. A Canadian scientist using infrasound stations — established to watch for nuclear weapons testing — was able to estimate its size.
“It was a very, very powerful event,” says Margaret Campbell-Brown, an astronomer at the University of Western Ontario in London, Canada, who has studied data from two infrasound stations near the impact site. Her calculations show that the meteoroid was approximately 15 metres across when it entered the atmosphere, and put its mass at around 7,000 metric tonnes. “That would make it the biggest object recorded to hit the Earth since Tunguska [in 1908],” she says.
Yesterday the Russian Emergency Ministry released a statement reporting more than 700 people injured, mostly from flying glass shards when windows blew out. Of course, this official number refers only to those injured badly enough to seek medical aid and be recorded, which means the actual number of injuries is far higher. That number also does not reflect the subsequent medical issues that will surely be coming as people all over the Chelyabinsk region deal with living and working in damaged buildings in the middle of the Russian winter. It will take a very long time to get all of those windows and doors replaced.
Russia Today put together a “greatest hits” video from various dash cam recordings of the meteor’s fiery atmospheric entry and subsequent explosion. It will save you a lot of video viewing time (and has already been viewed 13.5 million times, wow). Full screen if you can — most of the footage is HD.
The explosion is the very definition of blinding. Truly impressive.
What that video doesn’t capture is the shock wave that broke so much glass, scared people half to death, and injured hundreds. Here is CCTV footage of a couple in their office, chatting, when their window blows in:
Here is one of the more stable videos featuring the actual sound of the shock wave and subsequent explosions. What’s amazing about this is that you’re hearing it from inside a building and it’s still that loud…and that there are so many explosions.
For sheer power of sound, however, you’ve got to watch this one, which is taken outside. The videographer understandably freaks a bit when the shock wave hits, and from that point you can’t see much, but you can still hear.
What a day in Russia. On the one hand, I’m envious of everyone who got to experience this, but on the other hand, I feel for the folks who are having to deal with the aftermath.
And all this from an object estimated to be just 15 meters across.