Today we start to get some refinement on the preliminary answers. Most startling of all of these are the size estimates. The original numbers given by the Russian Academy of Sciences were that it was about 2 cubic meters, and 10 tons. That was handily blown out of the water by estimates made from infrasound stations, which put the numbers at 15 m diameter (~1700 cubic meters) and 7000 tons.
This morning that number has been further increased to 17 m diameter and 10,000 tons. This thing was approaching the atmosphere at 18 km per second, and is estimated to have released 500 kt TNT equivalent of energy during the event, over a period of 32.5 seconds. To put that energy in context, the “Little Boy” bomb dropped on Hiroshima at the closing of World War 2 had a yield of approximately 16 kt. So, assuming it was shedding energy at a constant rate (which it wasn’t) it is almost exactly the equivalent of a Little Boy detonation for every second it was in the atmosphere. For a while this thing was glowing brighter than the sun.
So, It entered the atmosphere, created an airburst at between 30-50 km altitude, and is known to have hit land in at least three places – two near Chebarkul lake (an impressive picture of the hole left by one of them is available here), and another 80 km away near the town of Zlatoust. There’s reports of another couple of pieces that may have come down in Khazakstan as well.
Looking forward to seeing what comes of any samples they recover, which will tell us what kind of meteorite it is, and will probably lead to some recalculation of the numbers given so far.
In the mean time DA14 passed – as expected – without incident.
I’ll leave you with a pretty incredible animation that puts the spotting of these smaller asteroids in some perspective. This demonstrates the history of asteroid spotting over the last 30 years far better than any plain description can. What else is out there?