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Posted on 09/26/2009 9:43:01 PM PDT by LibWhacker
If a “KT event” were to happen again...it would be a very large pile of not good.
Think how lucky the dinos were, they had no knowledge of asteroids or collisions, just lived along until Whammo, death from the sky. BTW, if we are hit every million years then it has skipped many, many millions of years. The dinos lived for far more than a million(about 185 million)before being smacked(if that is what actually happened) and reptiles were around for serveral hundred million before the Dinos came along. As the article points out it has been 70 million years since the Dinos went under.
So that begs the question: If only one major Asteroid has hit earth over the last 500 million years or so, how do they come up with the "once every million years" figure? BTW, I believe there was one other major extinction of life they didn't mention here, after the Dinos.
It’s a game of pinball, bowling, or marbles on a cosmic scale...
http://www.youtube.com/watch?v=LyzIau5dBao&feature=related
“advanced life”... sounds like the DU’rs will get by unscathed. (and, sadly, a few freepers...)
Right, this article is a badly edited version of a longer talk Hawking gave. A link to that talk is on the Daily Galaxy website. Haven’t read it yet, myself, so I don’t know if he was more careful than the editor, BUT I’m pretty sure he’s talking about asteroids measuring one kilometer or more in diameter. Those do hit us about once every million years. The 10 kilometer monsters, like the one that got the dinosaurs, hit about every 100 million years.
Obvious Hand of God ping!
“The first this to understand about the KT event is that is was absolutely enormous: an asteroid (or comet) six to 10 miles in diameter streaked through the Earth’s atmosphere at 25,000 miles an hour and struck the Yucatan region of Mexico with the force of 100 megatons -the equivalent of one Hiroshima bomb for every person alive on Earth today. Not a pretty scenario! “
Let’s see ... 100 megatons = 100 x 10^6 / 12.5 x 10^3 (Hiroshima bomb yield) = 10,000.
Correct me if I’m wrong here, but 10,000 does not quite equal 6,000,000,000.
Maybe they meant gazilliatons?
Today, a land impact of a 100-meter diameter meteor or comet will cause ENORMOUS long-term damage, not only will we have the shockwave from the impact (both through severe ground shaking and the gigantic air blast effect), but the impact will kick up a huge amount of dirt and rocks that will rain down potentially a couple of thousand miles away--and the debris will be a hotter than the melting point of lead. Such an impact will cause essentially a nuclear winter as all the impact debris thrown up in the air severely cuts the amount of light from the Sun possibly for a couple of years.
20 kilotons = 2 x 104 tons
Go!
Ah ... now that makes sense. But it’s not how the article was writen. Went to wiki. They say 100 million megatons, too.
written ... whatever.
1014/(2x104) = 5 x 109.
More if you use 12.5 kilotons for Hiroshima. Or perhaps this talk was 10 years ago and Hawking was using 20 kilotons for Hiroshima. I've always heard 20 kilotons. In any event, way more than 10,000.
Agreed. But the articles says “100 megatons,” hence my comment.
Did I read that wrong? Going back to check ...
Nope, I read it correctly. :)
Lol, okay as long as we agree that the impact released as much energy as 5 or 6 billion Hiroshima bombs, roughly one Hiroshima-sized bomb for every person on Earth (and not enough for only 10,000 people). Ten thousand Hiroshimas is nothing in comparison. Cheers! :-)
The probability of asteroid impacts is one of the factors I have argued is omitted from the Drake Equation for calculating the likelihood of intelligent alien life, and significantly reduces the probabilities of other such life.
Most stars in the Milky Way are clustered in the Galaxy Center, unlike Sol out in the relatively spacious spiral arms. Stars being more densely packed would increase the gravitational influence on nearby stars, unsettling their own Oort Clouds and driving in killer comets and asteroids towards the inner rocky worlds.
>>>How many times in our galaxy alone has life finally evolved to the equivalent of our planets and animals on some far distant planet, only to be utterly destroyed by an impact? Galactic history suggests it might be a common occurrence.
As far as I know, there is no such evidence of external life whatsoever. Comets and asteroids we have confirmed and studied. Alien life is just a hope, not something so casually to assume.
It should say, "100 million megatons."
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