Skip to comments.Supernova debris found on Earth
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
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.
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.
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 demonstrates that the Earth is not independent of its cosmic environment"
This article caught my attention because of the title. I've always been under the impression that all of the complex atoms that are the basic building blocks for, well, just about everything, including us, was formed in stellar explosions, either novas or super novas. In that case the title is pretty dumb as everything we've ever encountered is basically supernova debris.
On reading the article I thought a bit more about things like global warming. How many billion other variables haven't these clowns taken into account?
Then I was reminded of this thread:
After a Trio of Explosions Scientists say Supernova is Imminent
I think the moral of these articles is duck and cover!
BS is my first reply. Someone is looking for a grant.
"Ancient explosion may have affected climate..."
No way! Only humans (especially SUV owners") can affect the earths climate.
I'm too ignorant for this thread. But I did read that what we call "Cosmic Rays" are in fact "heavy iron nuclei" iron isotopes stripped of their electron shells, I gather. Traveling at near light-speed, these are by far the most damaging, penetrative form of deep-space radiation and the biggest complication of interplanetary human travel.
I didn't know Michael Moore was that old!........
Undoubtedly more stuff the klintons stole when they left the Whitehouse.
2.5 million years is an eyeblink in cosmic terms.
An "At least one luddite has found this thread so far" ping.
Catastrophism for atheists ping.
"Supernova debris found on Earth"
Could someone let me know when it gets to eBay?
Actually, predicting the past is no trick.
Accurately interpreting it, however, is another matter.
always my first assumption about "science" in the news. However, just because a scientist is pimping for federal money, it doesn't mean they are 100% off the mark. Merely suspect and worthy of close scrutiny.
Check the data! Always check the data!
Well, since I reference the fact that basically everything (except Hydrogen and Helium) is only possible as the result of a nova or supernova.... it's already on e-bay.
In fact, everything on e-bay is a supernova remnant, if you think about it in the right way....
Yes, right here and all over the Web, too:
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.