I was flipping through the new releases on Netflix this morning when I pleasantly stumbled across a NOVA documentary that aired on PBS last year. If you haven't seen it and have Netflix, I recommend checking it out. "NOVA: Meteor Strike" Excellent video clips, tracking, data analysis, and entertaining, too. I learned more than a few highly interesting gems and tidbits. One team of scientists on the other side of the globe were computing the path from videos - but not from the ones you might expect. They had footage from several municipal street cams, and were using the lampposts on the streets - tracking their rapidly moving shadows from the light of the meteor kind of like sundials. They said this was the most highly documented meteor strike of its kind by video, all due to the huge popularity of dash cams in Russian for legal protection and insurance purposes. (!) The incoming speed was 40K MPH. Explosion took place at an altitude of about 15 miles. This caused a delay of three minutes between the visual show and the huge shock wave that caught people by surprise. I think they approximated at 100 megatons of TNT. I was extremely surprised to learn that the brilliant light and the explosion are not caused by high temps from atmospheric friction. When a puppy like this comes at us at 40K mph, it's the pressure bubble that forms in front of the leading edge of the meteor that super heats the atmosphere and precipitates both the light and the stress the ultimately causes the explosion. The program was a great ride for me, as you can probably tell.