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Space Earth

Exploding Stars May Have Caused Mass Extinction On Earth, Study Shows (phys.org) 30

schwit1 shares a report from Phys.Org: A new study led by University of Illinois, Urbana-Champaign astronomy and physics professor Brian Fields explores the possibility that astronomical events were responsible for an extinction event 359 million years ago, at the boundary between the Devonian and Carboniferous periods. The paper is published in the Proceedings of the National Academy of Sciences. The team concentrated on the Devonian-Carboniferous boundary because those rocks contain hundreds of thousands of generations of plant spores that appear to be sunburnt by ultraviolet light -- evidence of a long-lasting ozone-depletion event.

"Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer, too, but evidence for those is inconclusive for the time interval in question," Fields said. "Instead, we propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone." The team explored other astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions and gamma-ray bursts. "But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period," said graduate student and study co-author Jesse Miller.

A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years. However, fossil evidence indicates a 300,000-year decline in biodiversity leading up to the Devonian-Carboniferous mass extinction, suggesting the possibility of multiple catastrophes, maybe even multiple supernovae explosions. "This is entirely possible," Miller said. "Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion."
"I'm sure somebody has a GRB or similar in their 2020 pool of what could go wrong next," adds schwit1.
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Exploding Stars May Have Caused Mass Extinction On Earth, Study Shows

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  • And yet our very distant ancestor survived the event.
    • Just googling this a bit, it appears our great** - grandparents of that era were "Tiktaalik, an intermediate between fish and four-legged land animals... The fleshy fins of its lungfish ancestors are evolving into limbs."

      Dinosaurs were still 10's of millions of years in the future.

      https://www.newscientist.com/a... [newscientist.com]

  • Fermi Paradox (Score:3, Interesting)

    by dhudson0001 ( 726951 ) on Thursday August 20, 2020 @08:20AM (#60422235)
    Perhaps the time it takes for a civilization to develop interstellar travel exceeds the time it takes for a supernova event to occur nearby.
    • You don't need interstellar travel to survive a distant supernova (even if this hypothesis is correct,) you just need caves or lead plating.
      • Re: (Score:2, Funny)

        by Anonymous Coward

        And lots of freeze dried and canned food and water to last a few hundred thousand years..

      • Re:Fermi Paradox (Score:4, Interesting)

        by HiThere ( 15173 ) <charleshixsn@NOSpaM.earthlink.net> on Thursday August 20, 2020 @10:28AM (#60422655)

        Well, for this one what you need it undersea cities that don't need support from land based civilization. Most of what they're talking about would be countered by a good blanket of water. So if there was a die-off of ocean based life at that time, it means that their explanation is probably wrong. Of course, food chains are complex, and you'd expect a minor extinction event even among oceanic creatures, but nothing major. On land you'd expect something major. Burrowing creatures might survive, but their food supply won't do as well.

      • So you survive the first couple days/weeks/months or if extremely "lucky" years, then die after suffering and struggling ever single second day and night the entire time. What about the other 100k+ years? If an event like this were to happen in our life time, I would much rather go hiking in the mountains, find a cliff high above a beautiful scenic river flowing through a lush green valley and jump. At that point I would have no fear at all of dying. Just seeing the beauty of our planet one last time be
  • by Anonymous Coward

    I recall reading an analysis suggesting there are x-ray beacons from supernovae bright enough to create a sterilization event anywhere in space, including on Earth every 100 million years or so. If true, that would go a long way toward explaining why we haven't seen evidence of E.T.

  • Great, now the by humans created climate change deniers can come up with yet another theory that it is not the CO2 that is causing it.
    • Re: (Score:2, Interesting)

      by Anonymous Coward

      I'm a denier, or what you'd call one... But we don't deny CO2's effect, only that man made sources of CO2 are not the primary cause of climate change. But I don't deny climate change is happening, only that it's not as dire of a situation as we are told.

      I'm not convinced that the effects of climate change can be controlled by man and the wholesale economic damage the proposed solutions to address climate change are unwise (if not pointless). In general, I see the wanton destruction of our economy and the

  • There would be remnants
    • There would be remnants

      " Guilty" ones?

    • by habig ( 12787 )
      Yes, but that long ago is around an orbit and a half of the Sun around the galaxy. SN remnants in terms of nebula don't last nearly that long (10-100kyr tops), and if there was a neutron star left over, they often shoot off to the side at great speed (if the explosion was asymmetric), so also long gone. Note that there's a much better picture about whatever SN created the "local bubble" https://en.wikipedia.org/wiki/... [wikipedia.org] But, that was only 10-20Myr ago: and it's still a fuzzy story. The one in TFA is
  • Wouldn't we be able to see the debris from a supernova 65 light years away? I dunno, exploding stars may have caused mass extinctions and exploding stars made the matter that makes up the Earth to begin with. It all works out in the long run.
  • Some type of ray weapon bombarding the planet, lucky they didn't have a death star!
  • Check out this informative article on 2020 QG which is what it's called.
    Apparently meteorites of this size hit our atmosphere multiple times per year and always vaporize high in the atmosphere.
    https://earthsky.org/space/clo... [earthsky.org]

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