Posted on 11/24/2004 1:22:08 PM PST by Phsstpok
Published online: 02 November 2004; | doi:10.1038/news041101-5
Supernova debris found on Earth
Mark Peplow
Ancient explosion may have affected climate and, possibly, human evolution.
Cosmic fallout from an exploding star dusted the Earth about 2.8 million years ago, and may have triggered a change in climate that affected the course of human evolution. The evidence comes from an unusual form of iron that was blasted through space by a supernova before eventually settling into the rocky crust beneath the Pacific Ocean.
Gunther Korschinek, a physicist from the Technical University of Munich in Germany, leads a team who in 1999 found the first deposits of supernova matter on Earth1. But it was impossible to date the supernova accurately from those samples, because the material was distributed through several different layers of rock.
The team has now analysed a different piece of ocean crust, where the supernova detritus is concentrated into a clear band of rock that can be accurately dated. The researchers found small but significant amounts of an isotope called iron-60 in the rock, which could only have come from a supernova.
"We've looked at all the possibilities and we can't find anything else that could produce such quantities," Korschinek says. The researchers report their results in the latest issue of Physical Review Letters2.
"It represents an experimental triumph and a milestone in this field," says Brian Fields, an astrophysicist from University of Illinois at Urbana-Champaign. He argues that the result marks the birth of a completely new area of research, which he calls "supernova archaeology"3.
Close shave
Comets and meteorites also deliver matter to Earth, but they always come from within our Solar System. Supernovae are the only known source of interstellar debris. "The very fact that a supernova can dump material on the Earth is, to my mind, rather spectacular. It demonstrates that the Earth is not independent of its cosmic environment," says Fields.
When the iron-60 arrived from space, it was evenly distributed all over the Earth. But the signatures are only detectable in crust that has lain undisturbed for millions of years, such as certain parts of the Pacific Ocean floor. This particular crust was taken from an area a few hundred kilometres southeast of the Hawaiian Islands in 1980. It was collected by oceanographers who were investigating the rocks as a potential source of rare mineral ores.
Korschinek estimates that the supernova was between about 100 and 200 light years away and happened 2.8 million years ago, give or take 300,000 years. The explosion can't have been too close to Earth, or it would have delivered enough radiation to cause mass extinctions. Conversely, if the supernova was any further away, more of the iron-60 would have been filtered out by the thin wisps of matter drifting between the stars.
Cooling rays
This means the supernova would have been at the right distance to spray out a stream of cosmic rays that could have increased the cloud cover on Earth. Korschinek calculates that there may have been 15% more cosmic rays arriving on Earth than normal for at least 100,000 years. This is not enough to actually kill anything, but was perhaps sufficient to change the Earth's climate.
The increase in cloudiness would have cooled the surface, tying up water as ice at the poles and leading to a dryer climate in Africa. Climate records in rock cores match the dates of the supernova event.
"Some people believe this climate change in Africa was a driving force in our own evolution," adds Korschinek. The argument is that a drier climate in the continent would have forced humans to adapt4, and to spread out to other, wetter areas.
The team is now looking for other unusual isotopes in the crust sample, which may reveal more about the type of star that caused the supernova. But there are probably 10,000 times fewer of these atoms than of the iron-60, says Korschinek, so they will be extremely difficult to measure. "We're sweating, and I don't know if we will succeed," he says.
It is Bush's fault!
There was a rock...the monkey got cold...and it evolved because it needed to build a fire. Well Halleluiah! They proved the theory. No more debate necessary.
Not true. Looking at the daughter product ratios gives the initial date and isotope composition.
This may be a really stupid question, but why are various elements contained in deposits and veins? I don't see any reason why iron, uranium, gold and other mineral atoms would gravitate toward each other. I would think that elements would be fairly evenly mixed.
For sure, God did it. Those of us who study physics, chemistry, etc., are simply teasing out the rules of the mechanism He set up to do so.
I'm not a geologist, but I think heavy metals tend to gravitate towards each other in the semi-liquid mantle of the planet because they have similar densities, and so tend to move around in the slow convection currents of the mantle in similar ways.
In short, what you see now reflects not the primordial dust cloud that the Earth formed from, but an Earth molded by billions of years of geological activity.
Not without a confrimation ...such as a hammer with an inscription that tells us that this hammer was made in Nashville, Tennessee by the Thor Iron Works on 2 August 1914 AND you've got the ironworker that made that particular hammer testifying on oath that he indeed made that particular hammer on that date.
If a rock is a billion years old... you've got to have another sample of rock that you can prove to be a billion years old. Otherwise... there is not a word of truth in it.
You make a good point. Catastrophism on the moon, on Mars, on Jupiter and now a supernova. But catastrophism on earth? Can't be, because it would disturb uniformitarian sleep.
It's Bush's fault.
Redleg Duke, meet Redcloak.
Redcloak, meet Redleg Duke.
The Earth Sun you me everything IS Supernova debris.
Jeez, did I miss a new physics revolution? I thought every element over an atomic number of 26 was evidence of super-nova activities...
Nevermind, I should have read on. /Emily Litella mode
Barbarian! Every element is a miracle. Doncha know anything?
This article isn't going to win any awards for scientific accuracy in reporting.
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Any element with an atomic number greater than iron is supernova debris.
BS is right.....its called Grant Trolling.
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