Posted on 12/01/2013 7:37:42 AM PST by SunkenCiv
Wittke et al. (1) state
“
The impactor mostlikely broke apart in solar orbit before en-countering Earth, as do most comets, includ-ing Comet Shoemaker
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Levy 9.
”
However,Shoemaker
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Levy 9 broke up while in orbitabout Jupiter, and the tidal fragmentationprocess leading to impact on Jupiter doesnot apply to comets in solar orbit or for ap-proaches to terrestrial planets (4). A sponta-neous breakup in heliocentric space, suchas one recent example (5), would have tobe exquisitely timed for an expanding cloudof fragments to strike the Earth. Near-Earthcomets have average lifetimes of at least acentury before breaking up. Within monthsafter disintegration the comet fragmentswould be dispersed over an area much greaterthan that spanned by the Earth, preclud-ing many nearly simultaneous impacts.Thus, dispersed impacts of multiple frag-ments would be at least 1,000 times lessfrequent (probable) than the impact of asingle nucleus.
I should vacation in Florida, no reason...
Thanks bogie.
If the breakup of the comet were caused by an encounter with the Earth, the comparison with SL-9 would be apples-apples; Comet ISON had its encounter with the Sun, so at least some of the fragments are likely to collide with the Sun, or be ejected. More fragments means more to track, because without tracking, there’s no way to know whether things are on trajectories to collide with Earth.
Yes, but the smaller they are, the harder they are to track. Something the size of a car could wipe out London.
A car sized object would make a pretty serious whump, and could destroy (or render unusable) a skyscraper, depending on how much braking resulted from its trip through the atmosphere. The car-sized bolides I’ve seen in photo wound up partially embedded in the ground, but relatively undamaged.
Something about 100 feet across (Tunguska size) would knock down nearly everything in London, and secondary damage (natural gas fires for example) would produce conditions difficult to get under control. If we figure a car is, hmm, to make it easy on the old ‘Civ brain, 20 feet, a 100 ft diameter would be five times in three dimensions, or 125 times the size and mass etc, give or take what both are made out of. Velocity at impact will be larger for larger objects, because the atmosphere will do little to slow them down.
Something 100 yards across (Meteor Crater size) would destroy everything for miles and leave a 3/4 mile crater where, for example, the City of London (that’s the square mile or two of medieval London) stands. That’s three times the size of a 100 footer, in three dimensions, so, 27 times the mass.
It’s staggering to think about something, say, a mile across — the impact of which would literally end civilization and likely kill 99% of humans, and untold numbers of animals; 300 into 5280 goes 17 times (and change), so, 17 cubed for the mass.
The Chicxulub impactor was about 10 miles across, or 1000 times larger than a 1 mile object...
The whole thing seems to hinge on what it is made of and the angle that it comes in at. The one over Russia last year came in at angle that allowed for plenty of ablation and force dispersion. Nichole/iron would probably make it to meteorite status with much more ease.
Anyhow, this subject is much more important to the survival of humanity than most people think.
Besides angle, the composition is important; mostly metal bolides are more likely to strike the Earth than carbonaceous chondrites, which fracture and/or burn up more often than not (depending on size of course). :’)
A former coworker (he’s now deceased, but that’s not why he’s “former”) who tested out at over 150 IQ was one of those who claimed the atmosphere would just burn up anything from space. I’ve always been a little suspicious of IQ numbers, but clearly they don’t mean much compared with a little edge-a-ma-cation. ;’)
As I think you said, our survival hinges on whether we see them coming and do something about it.
Yepper!
I’m sorry I missed this one:
ISON’S Incoming Debris Hitting the Sun.
http://www.freerepublic.com/focus/news/3101698/posts
This thread has been pulled.
Pulled on 12/14/2013 4:15:24 AM PST by Admin Moderator, reason:
Idiocy
Okay
[based on the search hits on that title, it’s more nutbar talk about how the “real” information about the “threat” of Comet ISON is being “suppressed”]
I saw that one and decided it would be too irritating to waste time on explaining why its crap.
I know I’ve said this before, but I wanted again to thank you for posting APOD along with your other stuff. It’s a wonderful diversion from the more pedestrian matters of politics and something most of us just don’t think to do on our own. It’s good to take a step back and behold he mysteries of God’s creation shown in the wonders of His universe.and SunkenCiv wrote:
It’s staggering to think about something, say, a mile across — the impact of which would literally end civilization and likely kill 99% of humans, and untold numbers of animals; ... the Chicxulub impactor was about 10 miles across, or 1000 times larger than a 1 mile object...First Civ, I second everything Shibumi wrote -- your APOD and related posts are wonderful and expand my horizons every time! Thank you SO MUCH!
And second, today I have to go out and plow and shovel a lot of snow (I'm in upstate NY), and it's a nasty, cold, difficult chore. But thinking for a minute about a big meteor just made it all seem a lot more tractable! God never throws anything at me that I can't handle if I just dig into it.... My perspective broadened, my mood improved immediately, and I'm ready to go out and brave the cold! Go figure....
Thank you!
Hat Tip!
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