Asteroid 2012 DA14 has moved on, and the Russians are busy cleaning up the mess from yesterday’s fireball. Hopefully a few people are also busy looking for meteorites from the fall. The only meteorite-maybes I’ve seen photos of are the small, black rocks found around the perimeter of the hole in Chebarkul Lake, west of Chelybinsk.
If these are indeed meteorites from the bolide, they remind me of the black, carbonaceous debris dropped by the Tagish Lake fall over the Tagish Lake area in British Columbia on January 18, 2000. Carbonaceous chondrites are fragile, carbon-rich meteorites that easily shatter into dust and small bits during a fall. If that’s what we’re dealing with here, meteorite hunters better get cracking – this type erodes quickly. Divers found no trace of any meteorites in the lake at the bottom of the hole today.
It is odd though that two days have gone by without a single significant fragment found. Meteorites, which develop a black fusion crust on atmospheric entry, would show up beautifully against the snowy Russian landscape. So what gives? How long will see purported Chelyabinsk “meteorites”pop up on eBay before the real item finally shows? Only hours after the fall, the first dubious specimens appeared on the auction site. Not a one of them looks like a fresh fall and some are clearly not meteorites. Buyer beware!
As for the Russian fireball being related in any way to the asteroid flyby, it is not. I’ve been in touch with folks who orbits and it’s becoming even clearer that we’re dealing with two very different asteroids. Not only were their orbits nearly perpendicular to each other from the perspective of the Earth, but it’s not possible for a cloud of DA14 fragments to even reach the city of Chelyabinsk at 55 degrees north latitude in Russia.
Since the fragments would approach Earth from due south nearly parallel to the planet’s axis, if they hit the planet, they’d strike the southern hemisphere. From the fragments’ very-close-to-Earth perspective, Chelyabinsk, Russia is on the far or opposite side of the globe and totally out of sight. Amateur asteroid discoverer Dr. Marco Langbroek uses this analogy and I paraphrase slightly:
“Compare it with a car. A bird flying toward your car will always hit the front of the car – it cannot hit the back of the car. Chelyabinsk at 55 North latitude is “the back of the car” in this comparison, given the approach direction of 2012 DA 14 and any fragments of it.”
We place a lot of faith in coincidence because, well, if you drop a plate, it breaks. The two are related. So if two close meteors or asteroids appear around the same time, many of us make the assumption they’re related too. It totally makes sense to wonder about a connection between the two events, but once the data is in, we need to take another look at our surmise. Speaking of data, we’re still waiting on radar images from the Goldstone antenna. As soon as they’re available, you’ll see them here.
I’m curious if any of you got to see the asteroid flyby either through binoculars or telescope. If so, we’d love to hear your story. Clouds were cruel here in Duluth, Minn., but I stood at the telescope and waited. And waited. Finally, a few thin openings passed the asteroid’s location just above the bowl of the Little Dipper about 7:15 p.m. (CST). There was just enough time to identify DA14 and watch it scoot north. One minute of joy followed by hours of clouds.
Cosmic debris rains down through the atmosphere nearly every day, accumulating at a rate of 37,000 to 78,000 tons per year. While that may sound like a lot, much of it is dust or passes unseen over the oceans.
At least a half-dozen times a year, however, a fireball burns up over a populated area and drops meteorites. Their fall is pinpointed by careful analysis of the angle of entry based on eyewitness reports, Doppler weather radar, security cameras or even dashboard cams, as we saw in Russia on Friday. Once the word is out, everyone from those closest to the areas of impact to meteorite hunters from across the planet are eager to find a piece of otherworldly treasure. The Chelyabinsk region has been pretty much off-limits to foreigners until recently, so it should be interesting to see who gets in and out without being arrested.
What they’re looking for are leftover fragments from collisions of bodies in the asteroid belt between Mars and Jupiter. Over the eons, Jupiter’s gravity nudges the shattered rocks out of the belt, sending them toward the inner solar system. Millions of years later, those fragments may hurl toward Earth. As the space rocks plummet through the atmosphere, the heat and pressure become so intense that even a fairly large object, say 13 to 50 feet across, will more often than not burst into harmless pieces that fall to the ground as meteorites.
The famous Peekskill fireball of October 9, 1992 that dropped a meteorite that smashed the rear end of a Chevy Malibu
A 13-footer hits our planet about once a year. One the size of Friday’s fall in Russia — about 50 feet across and weighing about 7,000 tons — strikes Earth about once every 50-60 years. The bigger they are, the less frequently they fall but the greater the consequences.
Yesterday’s flyby asteroid 2012 DA14, a rock about 150 feet across, would have caused regional devastation had it struck in one piece. One that size only rings our bell every thousand years. An asteroid of about 0.9 miles across could cause planet-wide devastation and climate change. The good news is such an event happens only once in half a million years.
While most of the 0.9-mile and larger near-Earth asteroids have been discovered, there are something like a million others as big as the one that zoomed by harmlessly yesterday. Sky surveys have ferreted out many of them, but many more remain to be found — before they find us. While there are many great ideas about how we might deflect an asteroid headed toward Earth, there are presently no programs underway to accomplish that goal.