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Chelyabinsk-Sized Asteroid Impacts May Be More Common Than We Thought
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."
It's nice to see that the author didn't buy into the myth that it's friction which causes the increase in temperature as a fast moving body move through the atmosphere.
"As this main mass plummeted through our atmosphere at a speed of 20 kilometers per second â" dozens of times faster than a rifle bullet â" the huge pressure it generated compressed the air in front of it, heating it up."
That kind of journalistic competency it worth noting.
Well, it's less than half the density of water.
Wikipedia tells me that iron has a density of 7.874 g/cm^3. A 60-foot-diameter asteroid has a volume of 4/3*pi*30^3 cubic feet, or about 113100 ft^3. So, units tells me that an iron sphere that size would be about 27,800 tons. So it's not as dense as a solid iron asteroid would be.
(T>t && O(n)--) == sqrt(666)
Not really. If you do the math, it works out to about 113,000 cubic feet (assuming a perfect sphere), meaning a roughly 203 lb/cubic foot of material, which is roughly half the density of cast iron.
If you did the sums you'd land up with about 1.75 tonnes per cubic metre, or not quite twice as dense as water. Even less if they're colonial short measure tons.
You know what, that's 4 times too big, used diameter for radius. I accept any shame heaped upon me.
is 71% water, such impacts should be around 2.45x as frequent as observed. Then add in the ones that impact in the Sahara and Australian Outback...
"I don't know, therefore Aliens" Wafflebox1
If it's less dense than water, then it would float. I highly doubt that any asteroid would actually float. Either your math is wrong (looks ok to me at first glance) or the numbers are off in the article.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
I am this AC, and I stand corrected. Good thing I'm not in the asteroid-density-measuring department, or I would not do too well.
Eight times. The shame shall be heaped upon you because it is eight times too big, not four. Flatlander chauvinist pig!
Bio questions? Ask me to start a Q&A journal. Computer analogies available for most topics!
You know, I just default in my head to nice little 2d pictures.
Figured out your mistake, you're using the diameter, not the radius, actual density is about 3.4 times the density of water.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
You know, the entire planet of Saturn would float if there were an ocean big enough to put it in ;-)
But yea, he's wrong anyway.
Yeah, I realized that too. Can I have partial credit for showing my work?
At least somebody got it right...
Stop. You had me at "Saturn would float".
I had just posted above me spotting a meteor above my town there, lasted around 3.3 seconds. Longest I have seen, most I have seen were 1.3s at best.
And it was a bright one too, none of these crappy weak streaks that vanish in to nothing, it was brighter than a typical helicopters search light in the distance, brighter than 3 planes worth of lights.
They have been increasing in frequency I've noticed over the years. And that sudden 3.3s meteor at that brightness, especially after that crap that happened in Russia, yeah, you bet your ass I freaked out a bit.
Also, may as well post this while I am passing by.
Best of the best clips from the Russian Meteor and Impact it had.
Crazy stuff indeed.
I sure hope nothing out there screwed up the generally stable meteor and asteroid belts, the last thing we need right now is the solar system screwing with our jump to the actual space age where we have an actual presence and not stupid silly satellites. That's baby steps, that isn't space stage, what's wrong with you?
Would you class the bronze age as when some dude accidentally kicked a lump of rock with metals in it? Course you wouldn't.
But really, it is fairly worrying.
I guess at least the good thing is they are actively looking in to it now. Hell, they even made a committee. Damned rocks gonna get UN sanctions on them if they keep that up.
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
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
Bedevere: "Wait. Wait ... tell me, what also floats on water?"
Villagers: "Bread? No, no, no. Apples .... gravy ... very small rocks ..."
Arthur: "A duck."
Bevedere: "Exactly. So... logically ..."
Villager: "If it ... weighs the same as a duck ... it's made of wood."
Bevedere: "And therefore?"
Villagers: "A witch! ..."
Have gnu, will travel.
I have a small piece of Chelyabinsk in my meteorite collection, It's a stony, not an iron, although it does have enough iron-nickel chondrules in it to be attracted by a magnet.
Yeah, density of about 3.4 gm/cm^3 is about right. (My piece, at just over 10gms, is about 3 cc.)
A 60-foot diameter iron is about what carved out the mile-wide Barringer (aka Meteor) Crater in Arizona. Irons tend not to airburst, or if they do, do it lower down in the atmosphere. It may also have been travelling faster.
Or have the just blame the Republicans?
Let's pre-emptively invade space!