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Space Science

Nearby Supernova Causes Mass Extinction? 71

Posted by michael from the theoretically-speaking dept.
hcg50a writes "AP has a story on Yahoo about a theory that a blast of gamma rays from a distant supernova destroyed the earth's ozone layer, allowing normally shielded intense UV radiation from the sun to kill life on earth. The second-largest extinction in the Earth's history, the killing of two-thirds of all species, may have been caused by ultraviolet radiation from the sun after gamma rays destroyed the Earth's ozone layer. Astronomers are proposing that a supernova exploded within 10,000 light years of the Earth, destroying the chemistry of the atmosphere and allowing the sun's ultraviolet rays to cook fragile, unprotected life forms."
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Nearby Supernova Causes Mass Extinction? More

Nearby Supernova Causes Mass Extinction?

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  • Mars? (Score:3, Interesting)

    by MobyDisk ( 75490 ) on Thursday January 08, 2004 @12:29PM (#7916220) Homepage
    Could this also have affected life on Mars, but it never recovered?

    (Rhetorical question - we can't really know)

    • Re:Mars? (Score:1, Interesting)

      by Anonymous Coward
      One theory proposes that Mars lost its atmosphere after losing its magnetic field. Without the protective bubble of the field, the solar wind can slowly erode the atmosphere.
      • I've heard that theory, too. But Venus has no magnetic field to speak of, either, and has a much more dense atmosphere than the Earth.
        • Comment removed based on user account deletion

          • Re:Mars? (Score:3, Informative)

            by misterpies ( 632880 )
            The planet has reached a natural balance. The climate is stable. It's just very hot. The atmosphere is composed of heavier molecules than here on earth -- mostly CO2 -- so it can withstand much higher temperatures before being boiled off.

            Why? Atmospheres "boil away" when the molecules in the atmosphere are moving faster than the escape velocity of the planet. But while particles in a hot gases move faster than those in cooler sample fo the same gas, gases made up of heavy and/or complex molecules will have
    • Presumably, it would have affected life anywhere in the Solar System, so long as the life forms were exposed to the UV.

  • Silly Dinosaurs... (Score:5, Funny)

    by JavaLord ( 680960 ) on Thursday January 08, 2004 @12:31PM (#7916246) Journal
    They should have been using sun-bloc SPF-10,000,000
    • They should have been using sun-bloc SPF-10,000,000

      Um, the dinosaurs went out 65 mya (million years ago) in the Cretaceous extinction. Dinosaurs first evolved some time after the Permian extinction, which was about 225 mya. The article talks about the Ordovician extinction, 440 mya, which was long before dinosaurs evolved; in fact it wasn not very long after multicellular life first evolved (560 mya).

  • Of course (Score:3, Funny)

    by aridhol ( 112307 ) <ka_lac@hotmail.com> on Thursday January 08, 2004 @12:34PM (#7916295) Homepage Journal
    A supernova that's really nearby (such as our own sun) could put a huge damper on things, as far as life is concerned.
    • Life on Earth would have already been taken out by the Sun's death throes. Carl Sagan had a great explanation of this in COSMOS.

    • Re:Of course (Score:4, Informative)

      by Pembers ( 250842 ) on Thursday January 08, 2004 @12:44PM (#7916450) Homepage

      IANAP, but as I understand it, our own sun is too small to go supernova.

      • Re:Of course (Score:5, Informative)

        by Anonymous Coward on Thursday January 08, 2004 @12:59PM (#7916655)
        You're right. Our sun is a dwarf star. It's death will be marked by expansion into a giant red star, then compression into a small core of oxygen and carbon, and finally lights out. Check out the BBC's page on the death of stars [bbc.co.uk].
      • as I understand it, our own sun is too small to go supernova.

        Quite true, but a supernova is a really, really big bang. A star going supernova within a few light-years will cook us quite nicely. Sirius A, for example, is certainly large enough to supernova, and it's 8.6 light-years away. I don't have the numbers, but I strongly suspect that the gamma-ray flux from something that close would do a whole lot more than just hurt the ozone layer... not to mention the blast of particle radiation, moving at less

        • Sirius A, for example, is certainly large enough to supernova, and it's 8.6 light-years away.

          Not according to any current theory of stellar evolution. Sirius A is spectral type A, which means a mass less than 3 solar masses. Anything under 8 solar masses won't go supernova, so Sirius A is destined for the boring end: expansion into a red giant, loss of envelope as a planetary nebula, and senescence as a white dwarf.

          ...not to mention the blast of particle radiation, moving at less than C, that would f

  • Where's the remains? (Score:1, Redundant)

    by glm ( 84597 )
    Where's the nebula? We should be able to see the remains of a close-by super nova.

    Thanks.

    • is in the article.

      The galaxy has completed two rotations since the event, and given that the various components of the galaxy don't rotate perfectly synchronously, the remenant nebula is either not where you'd expect, or smeared out of all recognition.

    • Re: (Score:2, Informative)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion
    • The parent post cuts to the heart of the question: Where's the evidence?

      Well, the theorists admittedly don't have any direct evidence.

      There are other plausible scenarios that lead to an ice-age, not just NOx haze from nearby supernovae.

      Still, the idea that a nearby supernova has actually triggered an ice-age is very intriguing.

  • Wow. (Score:4, Interesting)

    by NegativeK ( 547688 ) <tekarienNO@SPAMhotmail.com> on Thursday January 08, 2004 @12:43PM (#7916434) Homepage
    I'm not sure if other hard-sci-fi authors have addressed this, but Stephen Baxter's Manifold Space used a theory like this to address the Fermi Paradox: if we assume that physical laws are constant throughout the universe, why hasn't there been contact with other species? His answer? A sort of galactic reset.. When conditions are just right, two neutron stars (or other heavy bodies) will enter a decaying orbit, and release gravitational energy in the form of gamma rays (I believe.) In short, resetting the biological clock of our galaxy. Different from destroying the ozone layer, but this article makes it seem a little less far fetched, doesn't it?

    • Re:Wow. (Score:3, Interesting)

      by Baron_Yam ( 643147 )

      It appears that there are several factors for creating a 'potential life zone' in the galaxy.

      Given our sample of one known case, we assume you need a Sun-like star, with an Earth-like planet in an Earth-like orbit, probably with an Earth-like moon. You also need outer gas giants to reduce the inbound crap that would otherwise beat the hell out of us. That's just the local stuff.

      You also need to have a solar system that won't pass through a dangerous region of space while life is trying to evolve... that

      • <i>You also need outer gas giants to reduce the inbound crap that would otherwise beat the hell out of us</i>
        <br>
        <br>
        I've heard this cited before, but I don't get it. Jupiter may be really huge compared to Earth, but compared to all the possible approach vectors of "inbound crap", it's not worth mentioning. Am I missing something?

        • is insufficient to answer you with any authority.

          However, I'll offer a guess or two - First, a gas giant will collect anything in a solar system's disk that is slowly spiralling inwards, as even if it isn't very close, it only has to pass close enough to perturb the path, drawing the object closer for the next pass. Second, (and this is a wild-ass guess) there may be other effects of a large gravitational field on chaotic structures (like asteroid belts?) that keep them dynamically stable and less likely

        • Re:Wow. (Score:2, Informative)

          by AuraSeer ( 409950 )
          It has nothing to do with "approach vectors." Large objects don't usually fall in from outside the solar system.

          The problem is leftover crumbs of planetary formation-- asteroids, planetesimals, the assorted random junk that has been circling the sun as long as the Earth has. In our system, Jupiter had the effect of removing that junk from our vicinity. It consumed a lot of rocks, and flung others out of the system by the slingshot effect. The remaining ones got shepherded into their own fairly circular orb

    • Re:Wow. (Score:3, Interesting)

      by hcg50a ( 690062 )
      Good point.

      The biggest problem with the Drake Equation is that it it way too simplistic. In our galaxy, there is definitely a habitable zone [spacedaily.com] which the solar system is in. If it were much closer to the center of the galaxy, there would be too many events like energetic supernovae that would kill all life on the earth. If it were much farther away from the center, there would not be enough heavy elements to form earth-like planets.

      Life is fragile and cannot tolerate too many nearby energetic events.

      • Sounds possible. Um, do you (or any one else) have any evidence or proof of a "habitable zone"? If not, please change the word "definitely" to "possibly". I will even allow "probably", but no, no, no, to "definitely". I do hope you are back on track, now. :)

        *cragen

      • Close, but not correct. Prof. Gonzalez got it wrong (sorry doc).

        There isn't a habitable zone - there is a developmental zone. It's the region where intelligent live can evolve in the absence of energetic local events, but with sufficent heavy elements.

        Once developed, life could certainly colonize worlds outside the so-called habitable zone quite easily.

        So it may be correct to say the development of intelligent life is rare in the galaxy, but that still doesn't answer the conundrum of where THEY are - e
        • I think it would be exceedingly difficult to colonize worlds outside the developmental zone.

          On the outside, you would either have to bring all your raw materials with you, or you would have to be able to manufacture them.

          On the inside, you would have to bring sufficient shielding or construct it and reconstitute your environment when it got damaged.

          Therefore, I think the habitable zone shrinks down to the developmental zone in practice.

          There's not really a conundrum of where THEY are: THEY are few and
          • On the outside, you would either have to bring all your raw materials with you, or you would have to be able to manufacture them.

            On the inside, you would have to bring sufficient shielding or construct it and reconstitute your environment when it got damaged.

            Considering that we are talking about a civilization with the hypothetical technology to routinely colinize 10's of billions of starts in the "habitable zone", neither of yourobjections seems particularly troublesome.

            As for building in an enviornmen
            • You're talking about people with building in a bad location, this whole line of questioning is talking about an intelligent species and humanity's intelligence is frequently brought into question.
    • The supernova thing happened in Robert Sawyer's "Calculating God". Aliens came to Earth searching for proof of a creator's existance and one piece of evidence was that all three worlds including the Earth had suffered near simultaneous mass extinction events. When a nearby star went supernova near the end of the book a creature believed to be this creator appeared and put up a shield to block the radiation from hitting the three worlds. It's a pretty good novel.
    • Greg Egan wrote "Diaspora" which deals with the atmospheric effects of a setrilizing blast of radiation from two neutron stars coaelescing nearby. Egan writes excellent hard sci-fi, and the rest of the stories in this novel (set in the same timeline, with characters appearing and disappesring from the stories) are all linked together - very good indeed.

      Dr Fish

  • Our aversion to going outside... (Score:4, Funny)

    by NanoGator ( 522640 ) on Thursday January 08, 2004 @12:44PM (#7916447) Homepage Journal
    ... has saved us!

  • reported on in 2003 (Score:3, Informative)

    by MonkeyBoyo ( 630427 ) on Thursday January 08, 2004 @12:46PM (#7916472)
    In 2003 this story [nature.com] was reported in nature.

    And here the link to the pre print [arxiv.org].

  • No Real Evidence yet... (Score:4, Interesting)

    by Slick_Snake ( 693760 ) on Thursday January 08, 2004 @12:50PM (#7916532) Journal
    "We think there is very good circumstantial evidence for a gamma ray burst."

    The article clearly states that they have no real evidence to speak of. The only thing they do have is the ice age that occured at the time of the extintion. They admit that no traces of a supernova near earth can be found, and blame it on the rotation of the Milky way.

    Melott said there is no known evidence of such a nearby supernova, but that in 440 million years the Milky Way would have rotated almost twice and traces of the explosion could have been moved during that time.

    I will give them that it is a possibility, but until they have some more convencing evidence I'm not ready to jump aboard.

    • Agreed, the article didn't describe hard evidence that the Earth was the target of a gamma ray burst 440 million years ago. Does anyone know where you would look for such evidence? Would there be a detectable chemical signature in soil sediments from this period? Or is this something you would need to look at moon rocks or cometary ices to find some evidence of the gamma rays?


    • is Greg Egan's Diaspora, in which a gamma-ray burst in a nearby pair of neutron stars lays down some heavy spank on Planet Earth. The predicted/imagined effects are pretty-well thought out, and would make for a stunning series of special effects.

      There's a references section at the end, which lists some nonfiction texts concerning GRBs and the possibilities of their existence.

  • Evolution? (Score:4, Interesting)

    by dnahelix ( 598670 ) <slashdotispieceofshit@shithome.com> on Thursday January 08, 2004 @12:53PM (#7916561)
    Could it also be a factor in Evolution?
    Increased exposure to radiation causing a period of increased mutations in the surviving species?

    • Re: Evolution? (Score:4, Insightful)

      by Black Parrot ( 19622 ) on Thursday January 08, 2004 @03:03PM (#7919182)


      > Could it also be a factor in Evolution? Increased exposure to radiation causing a period of increased mutations in the surviving species?

      The opportunities for species to radiate into vacated niches would probably have a much bigger evolutionary impact than the effects of a short-term boost in mutation rates.

      • I do understand that the 'vacated niches' would allow more for the success of a surviving species. However, mutation is integral, if not the foundation of evolution.

        Example: A species with a longer neck can more successfully get food (leaves) from higher branches, but something had to cause the longer neck in the first place.

        I like Dawkin's definition of life : The non-random survival of random self-replicators.

        In the random self-replication process, an absence of genetic mutation would not allow
    • Any extinction to this degree will have a huge impact on evolution. However, the severity of the impact is not caused so much from the radiation damage to DNA in surviving species, but from the removal of multiple species(sic "limbs") from the evolutionary tree. Granted, this may not set evolution back that far, but it will certainly cause a difference in the direction that it takes.

  • I remain unconvinced (Score:1, Funny)

    by Anonymous Coward
    I'm sorry, I can't lend my reputation to this theory.

  • Where's the Ka-Boom!?!? (Score:3, Funny)

    by damien_kane ( 519267 ) on Thursday January 08, 2004 @01:12PM (#7916834)
    There was supposed to be an earth-shattering Ka-Boom!!!
  • I believe this is very possible. We still haven't completely figured out GRB's, let alone the universe. I believe that mass extinction would be likely in any planet old enough to achieve the technology to determine it, and this due only to the lenght of time which presents opportunities for such events to take place. Sure, there's no proof, but it's interesting.

  • Meanwhile, geologists and archeologists debate the introduction of the Delicious Period to historical texts.
  • Like any good Slashdot reader, I haven't read the article, but if it says that the event killed off 2/3rds of the creatures here, then that implies that 1/3 were fine and survived.

    If that is the case, then they would have some protection strategy towards UV - are those animals currently still here? Humans sure as hell don't have that protection.

    And is that number only considering land/air based creatures - would it have any impact on sea life?

    It just would seem that if the ones that could survive the UV

  • the next big one primed & feisty (Score:5, Interesting)

    by iggymanz ( 596061 ) on Thursday January 08, 2004 @03:57PM (#7920117)
    and here's [seds.org] the ticking time bomb within 10,000 lightyears that's going to finish us off. It may in fact already have supernovaed, and the gamma ray clam-bake coming at lightspeed! Oh, and recently revised estimates indicate no more than 20,000 years to the big pop. This will mess up your hard disk.

  • This is a scenario that has appeared in science fiction before in, for example, Charles Sheffield's Aftermath and Starfire.

    What sticks in my mind is the thought that on a cosmic scale, these things happen. Whether it's meteor strikes, runaway greenhouse effects, or nearby supernovae, the universe/mother nature doesn't care. The universe is a scary place. It's just that we're around to complain about it now.

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