Archive for September, 2013

Sep 15 2013


Published by under Astronomy

Exactly seven months ago today, on February 15, a large fireball exploded over Chelyabinsk, Russia. The shockwave damaged buildings and injured as many as 1,200 people (mostly from falling/flying glass). Meteorite fragments showered the area, although the main mass may be at the bottom of a nearby lake. Thanks to KD Meteorites and the Colorado Coliseum Mineral and Fossil show, I now own one of those fragments.

picture of meteorite

It’s a small piece, 10.5 grams and about an inch across, with an almost complete fusion crust except for a small chip showing the interior. Under a magnifier, you can easily see the grains — including tiny grains of nickel-iron — that make up this chondrite.

Pretty cool.

What I think is really cool, though, is this: a year ago this little piece of rock was in space somewhere out around the orbit of Mars. The track of the meteor (aside: the atmospheric phenomenon of a meteoroid or asteroid burning up in the atmosphere is meteor, when it’s still in space it’s either a meteoroid (small) or asteroid (over 10 meters — at 18m Chelyabinsk was an asteroid), and any pieces that survive entry and hit the ground are called meteorites) was well recorded on many security cameras and dashboard cameras in the nearby town, as well as by an earth observation satellite. Projected backwards, it is highly likely that the Chelyabinsk asteroid was one of the Apollo group of Earth-crossing asteroids*. Meteorite orbit, from Wikimedia It was about 40 days past perihelion when it slammed into Russia. A year ago — five months before impact — it was roughly in the vicinity of Mars’s orbit. (I haven’t worked out where Mars itself was at the time, it could have been on the other side of the sun.)

This is not my first meteorite. Some years ago I was given a nice 87 gm (about 1/5 pound) fragment of the Canyon Diablo meteorite, which formed the famous Meteor Crater in Arizona, impacting some 40,000 years ago. It’s awesome to have a piece of what blew a mile-wide hole in the Arizona desert. It is awesome to own a piece of the meteorite which we saw a few months ago on TV, one of the largest in a century. It’s even more awesome to hold a rock in your hand and know that a year ago it was deeper in space than any one, and few robots, have been before.

I think I’ve found a new hobby.

*(The largest member of this group, 1866 Sisyphus, is estimated at 8.5 km diameter, 472 times the diameter of Chelyabinsk … or over 100 million times the mass. If — or when — it hits us, the impact would be equivalent to that of the Chicxulub dinosaur-killer. Nervous yet?)

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