Chelyabinsk meteor . . . Holy Carp!

I remember a photo in Science showing a meteor passing through the atmosphere above a Montana Lake boat dock. Back when film photos like that were rare. The really attention grabbing thing about that photo is a ~ 1000 mile contrail that is perfectly straight in a pure blue sky.

 

^^ Could it be this picture?: Astronomy Picture of the Day

If so, it was Jackson Lake, Wyoming, with the Teton mountains in the background. Or foreground compared to the fireball itself.

 

YEAH, that's it. Obviously a lot of my neurons are decaying, but that's the one.

 

Lots of details about the rock here:

Additional Details on the Large Fireball Event over Russia on Feb. 15, 2013

Including a 'keystone' ref to Brown et al. in Nature, 2002. pop that baby into google scholar and you not only get your free copy (a nice piece of work if you like log/log regressions), but links to 165 papers that have cited Brown. Absorb those, and you are the boss of bolide infalls. Too much for me though, even though they look like great fun. Am supposed to be working.

 

If you would be satisfied as a mini-boss on the subject, just add one more (also free) to your reading list

The impact rate on Earth

Very broad scope, and a few delightfully understated quotes like

"Objects greater than 1012 kg transit the atmosphere with little effect so final mass is similar to initial mass."

Clearly they mean little effect on the bolide, not little effect on the earth

One would have to read more to understand this quote

"...the best estimate for the chances of dying in an impact is still 1 : 20 000."

I don't get that at all. We know of no one who has thus died yet (there was a cow though). Maybe, for a big enough bolide, 1/20000 of humans die? Could we not as easily state that, for a big enough bolide, 1/1 of humans die?

 

When I have seen this estimate elsewhere, it has been clear that the vast majority of the risk comes from the largest but rarest asteroid impacts, the city-, country- and continent-killers. Not the puny air bursters like Tunguska, but the size of Arizona's Barringer Crater and larger.

This risk estimate also seems to be a moving target.

 

Ummmm... I think your math is a bit skewed there Bra... it IS about size and speed... more importantly = what it's made of... the crater in Arizona was made by one mostly of iron... Tunguska was not... and as far as we can tell, neither was the meteorite in Chelyabinsk.

 

When it gets sufficiently large, material content (or structural integrity to resist fragmenting in the atmosphere) no longer matters much, mass and speed pretty much tells the whole story.

 

"We are sorry, but this video is not available in your region due to the rights restrictions"

Wth?

 

Thanks for the pointer, I'll pull it up tonight.

 

Another big fireball hit in December, exploding in the atmosphere with an estimated 173 kilotons of energy, equivalent to a fairly good sized nuclear blast. But being over the Bering Sea, there were no apparent human witnesses, so it was found by satellite review and just announced.

A meteor exploded in the Earth's atmosphere with 10 times the energy of the Hiroshima atomic bomb - CNN
US detects huge meteor explosion - BBC News
Fireballs

 

If a meteor explodes in the wilderness.....

 

Got me revisiting the first page, quite the reminder.

 

me too, i thought it just happened.

funny, first the scientists told us we need to blow up the meteors, now they've moved on to sun spots.

 

"They" didn't move on, your attention did. "They" have gotten ever busier searching for and finding and tracking more hazardous objects. This one was tiny compared to the ones that are real hazards:

List Of The Potentially Hazardous Asteroids (PHAs)

 

I've always been a little dubious about "blowing up" a big rock that's on a collision course.

If a Tunguska-sized (100m - more or less) chunk is inbound then all you need is a kinetic weapon.
I've also always thought that 'God rod' was an interesting name for those things.
If there is NOT a God, then the name is meaningless.
If there IS, then you'd better hope that the Almighty isn't sensitive about copyrights, especially when you're using one as a point-defense weapon for your planet.

If you get much bigger than 100m, conventional chemistry fails beyond a relatively tiny Goldilocks-size range, and then you're left with physics as your final alternative - but I would prefer a 'nudge' rather than turning one big stone into zillions of radioactive little ones.
Given the time....

It sure would solve the whole AGW thing though.....

 

Well that's quite a thread bump...

 

Only 6 years. We've had plenty of thread bumps in the 10-14 year range