Chelyabinsk-Sized Asteroid Impacts May Be More Common Than We Thought 50
The Bad Astronomer writes "Using data from the Feb. 15, 2013 asteroid impact over Russia, scientists have determined that we may be hit by objects in this size range (10 — 50 meters across) more often than we previously thought, something like once every 20 years (abstract). They also found the Chelyabinsk asteroid was likely a single rock about 19 meters (60 feet) across, had a mass of 12,000 tons, and was criss-crossed with internal fractures which aided in its breakup as it rammed through the Earth's atmosphere."
Re:quite dense (Score:5, Informative)
Re:Friction versus increasing pressure (Score:3, Informative)
Phil Plait is a well-known astronomer. I'd say he's probably an astronomer first, a writer second. So one shouldn't be too surprised by his accuracy.
Missed a paper reference (Score:5, Informative)
The Slate article mentions there were two Nature papers, but the article summary above only gives a link to one. The papers are:
This one came up with 20 year frequency for these sized events: A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors [nature.com]
This one looked a bunch of YouTube videos and analyzed how it broke up as it went through the atmosphere:The trajectory, structure and origin of the Chelyabinsk asteroidal impactor [nature.com]
Re:Friction versus increasing pressure (Score:5, Informative)
No and no. Even if it were frictionless, the air molecules would still have to get out of the way. The object is moving at Mach 25 or more, 25 times faster than the air molecules can get out of the way (ie, the speed of sound) easily. Therefore the air compresses. Hypersonic fluid dynamics is completely unlike subsonic fluid dynamics.
Friction doesn't (well, hardly) enter into it.
Neither does semantics. You're wrong, and so are the dummies who up-moderated you.