It’s been two weeks since a “freaky space rock” blasted out of the sky above Chelyabinsk, Russia. At the time, the worldwide press breathlessly reported the extent of the amateur video footage and the ground-level damage and then moved on to other flavors of the moment. Meanwhile, what have we learned about our cosmic visitor?
A week after the event, Sky & Telescope reporters blogged about the composition and trajectory of the Chelyabinsk meteoroid. The recovered fragments are “ordinary chondrites,” the most common type of stony meteorites. These ordinary chondrites do contain flecks of metals, but also lots of silicates, as opposed to iron meteorites, which really are chunks of iron. The space rock was moving in a completely different direction from the asteroid that nearly missed the Earth the same day, so the events were unrelated, as much as our pattern-seeking human brains would like to deny.
S&T also reported that a scientist at the University of Western Ontario calculated that the near-Earth object (NEO) was cruising at 20 km/s when it hit the atmosphere. The “infrasound” detectors that are supposed to enforce the nuclear test-ban treaty picked up the blast waves — equal to about 30 Hiroshima bombs — from as far away as Antarctica.
Scientists suspect that the space rock came from (or was) an Apollo asteroid, a specific class of minor planets that cross Earth’s orbit. So, yeah, this should really point out the need to keep watch on the other Earth-crossers that may be whizzing by. The University of Hawaii is developing a “last-alert system” to complement PanSTARRS. And, as Chelyabinsk cleans up, local officials are figuring out how to market the newly famous city as a hot tourist destination. (It even has a travel agency called Sputnik!)