|
Diploid
Cuban


Registered: 01/09/03
Posts: 19,274
Loc: Rabbit Hole
|
One Of Earth's Greatest Mysteries: Solved
#5710706 - 06/04/06 10:55 AM (17 years, 7 months ago) |
|
|
http://www.smh.com.au/news/science/how-australia-was-born/2006/06/03/1148956584112.html
SCIENTISTS believe they have finally solved one of Earth's greatest mysteries: what caused the great extinction of life hundreds of millions of years ago.
The answer was revealed yesterday when an American team announced it had discovered the world's biggest meteor crater almost two kilometres under the ice in Antarctica.
They say a meteor almost 50 kilometres wide caused a 500-kilometre-wide crater deep under the Wilkes Land region of Antarctica, directly south of Australia.
The massive explosion from the impact probably created the continent of Australia, forcing it to break away from the existing land mass.
The incredible discovery caused huge excitement among Australian scientists last night. It could be the missing link in the geological formation of the continents. It would also answer why life on Earth was almost completely wiped out hundreds of millions of years ago.
The meteor the size of Sydney struck 250 million years ago and must have been the biggest explosion ever seen on the planet, far bigger than the 10-kilometre-wide meteor which hit east of Mexico 65 million years ago, wiping out the dinosaurs.
Ohio State University scientists who found the crater said the massive Antarctic crater could explain the global extinction in the Permian-Triassic period when all animal life on Earth died out, clearing the way for the dinosaurs.
The massive impact probably broke up the ancient continent of Gondwanaland, pushing Australia out on its long drift north to its current position. The landmass that became India shot off first, while Africa and South America broke off later.
"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," said Ralph von Frese, professor of geological sciences at Ohio State University.
Professor von Frese and Laramie Potts, a postdoctoral researcher in geological sciences, led the team of Ohio University, NASA, Russian and Korean scientists that discovered the crater.
They reported their preliminary results yesterday to the American Geophysical Union joint assembly meeting at Baltimore.
The scientists used gravity fluctuations measured by satellites to peer beneath Antarctica's icy surface, and found a 321-kilometre-wide plug of mantle material - a "mascon" in geological parlance - that had risen up into the Earth's crust.
Mascons are the planetary equivalent of a bump on the head. They form where large objects slam into a planet's surface. When the scientists overlaid their gravity image with airborne radar images of the ground beneath the ice, they found the mascon perfectly centred inside a circular ridge 482 kilometres wide.
"Based on what we know about the geologic history of the region, this Wilkes Land mascon formed recently by geologic standards - probably about 250 million years ago," Professor von Frese said.
Professor Michael Archer, dean of the Faculty of Science at University of NSW, said the crater could prove to be the missing link science has been waiting for.
"A meteor that size would have punctured right through the crust of the Earth and caused enormous damage to the planet," he said.
In that period 95 per cent of life on Earth was destroyed, he said.
"It's possible this is the missing key to what caused it."
-------------------- Republican Values: 1) You can't get married to your spouse who is the same sex as you. 2) You can't have an abortion no matter how much you don't want a child. 3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer. 4) We need a smaller, less-intrusive government.
|
drSE
Pseudo Reality



Registered: 12/19/03
Posts: 4,432
Loc: Twighlight Zone
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Diploid]
#5710966 - 06/04/06 12:18 PM (17 years, 7 months ago) |
|
|
Very interesting
--------------------
Grow Room
|
Colonel Kurtz Ph.D
What What?

Registered: 07/22/04
Posts: 11,113
Loc: Shadow Moses
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Diploid]
#5711583 - 06/04/06 03:14 PM (17 years, 7 months ago) |
|
|
Fascinating indeed, I can only imagine what such collision would do to the planet. A sight to be seen for sure.
--------------------
There's no better way to rock out than with your cock out!!
|
RuNE
bomberman


Registered: 09/23/00
Posts: 2,331
Loc: tartarus
Last seen: 7 years, 11 months
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Diploid]
#5715787 - 06/05/06 04:37 PM (17 years, 7 months ago) |
|
|
Thats a big ass crater. =0
Cool
-------------------- ~Happy sailing~
|
Asante
Mage


Registered: 02/06/02
Posts: 86,795
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Diploid]
#5716108 - 06/05/06 06:27 PM (17 years, 7 months ago) |
|
|
My God! So it punched right through O_O
Does anyone know the gigatons of that one?
-------------------- Omnicyclion.org higher knowledge starts here
|
Seuss
Error: divide byzero


Registered: 04/27/01
Posts: 23,480
Loc: Caribbean
Last seen: 2 months, 20 days
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Asante]
#5718015 - 06/06/06 06:11 AM (17 years, 7 months ago) |
|
|
> Does anyone know the gigatons of that one?
Very rough estimate: between 3.0 and 6.3 gigatons based upon the crater size. More probable towards the lower end. I am pulling 15 year old BDA numbers from my head, so please don't quote this as fact.
Edit: I am seeing some crazy numbers on the net for impact energies much, much larger than what I came up with. Claims in the 10E4 to 10E5 gigatons range. Using 10E4 gigatons, I come up with a crater size larger than the planet. The numbers I am using are for nuclear bomb damage assessment, and may not scale properly to such a large event.
Edited by Seuss (06/06/06 06:34 AM)
|
kotik
fuckingsuperhero


Registered: 06/29/04
Posts: 3,531
Last seen: 4 years, 24 days
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Seuss]
#5718363 - 06/06/06 09:48 AM (17 years, 7 months ago) |
|
|
i'll believe it when they put the CG version on discovery
-------------------- No statements made in any post or message by myself should be construed to mean that I am now, or have ever been, participating in or considering participation in any activities in violation of any local, state, or federal laws. All posts are works of fiction.
|
Asante
Mage


Registered: 02/06/02
Posts: 86,795
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Seuss]
#5718988 - 06/06/06 01:21 PM (17 years, 7 months ago) |
|
|
Quote:
Chicxulub Crater is an ancient impact crater buried underneath the Yucatan peninsula, with its center located approximately underneath the town of Chicxulub, Yucatán, Mexico. Investigations suggest that this impact structure is dated from the late Cretaceous, about 65 million years ago. The meteorite's estimated size was about 10 km (6 mi) in diameter, releasing an estimated 5.0×1023 joules of energy, approximately 100,000 gigatons of TNT[1], on impact. By contrast, the most powerful explosive device ever detonated, Tsar Bomba, had a yield of only one-twentieth of a gigaton.
Nuclear weapons direct their force to all directions, but an asteroid drives it straight into the ground. This perhaps accounts for the difference between nuclear weapons and asteroid impacts.
Your 5 GT hydrogen bomb might be just the thing we need in case such a rock is hurled our way, I don't think we'd discover such an asteroid in time for anything more fancy than brute force. 5 gigatons of TNT worth of Lithium deuteride still means 200 tons of this non-radioactive nuclear fuel. I think its the biggest beast we can assemble in space within say 2 years warning.
Imagine a 1.000 ton warhead being hurled at an approaching asteroid. Quite an engineering feat! Interesting factoid: during the fraction of a milisecond in which it functions it releases as much energy as the ENTIRE sun. Eat that you villain!
-------------------- Omnicyclion.org higher knowledge starts here
|
Diploid
Cuban


Registered: 01/09/03
Posts: 19,274
Loc: Rabbit Hole
|
Re: One Of Earth's Greatest Mysteries: Solved [Re: Asante]
#5719734 - 06/06/06 04:55 PM (17 years, 7 months ago) |
|
|
Nuclear weapons direct their force to all directions, but an asteroid drives it straight into the ground. This perhaps accounts for the difference between nuclear weapons and asteroid impacts.
Actually, beyond about 100 megatons, most of the energy rebounds out into space. This is why nuclear weapons are all smaller than this even though we have the technology to make them bigger.
I doubt any of the available models are very accurate in the gigaton+ regime.
-------------------- Republican Values: 1) You can't get married to your spouse who is the same sex as you. 2) You can't have an abortion no matter how much you don't want a child. 3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer. 4) We need a smaller, less-intrusive government.
|
|