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Space Science

Exploding Star May Have Damaged Life on Earth 239

Posted by Hemos
from the like-the-death-star dept.
Reedo writes "Scientists have proposed that an ancient supernova may have damaged our ozone layer, wreaking havok on terrestrial life. Previously no one had realized that a cluster of stars could have been so close to the earth during that time. But don't worry about it happening again anytime soon. The next expected supernova is nearly 500,000 light-years away and is too far from the earth to cause any damage."
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Exploding Star May Have Damaged Life on Earth

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  • I love how all the impending doom forcasts that
    come from NASA and such other large organizations
    are always closed with "But don't worry about
    this happening for (large number) of years."

    Sure, it's probably because we'll see it
    coming and still not be able to do anything
    about it, but I find the trend amusing none
    the less.

  • doh! (Score:4, Funny)

    by flynt (248848) on Monday March 11, 2002 @02:13AM (#3141315)
    But don't worry about it happening again anytime soon. The next expected supernova is nearly 500,000 light-years away and is too far from the earth to cause any damage."

    Too bad, I was thinking of a way out of doing my math homework tonight.
  • no... (Score:3, Funny)

    by doooras (543177) on Monday March 11, 2002 @02:13AM (#3141318)
    and i had come to believe it was all because of the anti-time anomaly
  • Inane (Score:2, Insightful)

    by prizzznecious (551920)
    I'm really unhappy with CNN. This theory is insultingly ludicrous.

    It's preposterous to think that there could have been even ONE supernova in our vicinity (let alone "several" as stated in the article) without obvious lingering effects, i.e., a remnant special star like a neutron star or a black hole and/or some sort of nebula. "Several million years" is nothing in cosmic time--the nebulae that those stars would have left would barely have dispersed at all.

    Not to mention that our position in the galaxy is somewhat peculiar. We are on the rim of a huge and empty vastness called the local bubble. The speculation (since there's a pulsar on the other side of the local bubble) is that the portion of space near us was cleared out by a big supernova some time ago (probably ~5-6 billion years ago, as our sun was almost certainly formed in its wake). How could these researchers possibly think that several supernova could have passed through without leaving similarly obvious signatures?
    • Re:Inane (Score:5, Informative)

      by snowlick (536497) on Monday March 11, 2002 @02:40AM (#3141410) Homepage
      "But Maiz-Appellanis and Benitez did some detective work and came up with the likely culprit -- a volatile star pack known as the Scorpius-Centaurus OB Association, which passed relatively near the solar system several million years ago."

      A google search turned up:
      The association is embedded in a large roughly circular structure; this is a huge bubble of hot gas created by the stellar winds of the numerous massive stars in the association and by several super-nova explosions, which happened in the Scorpius Centaurus association during the last few million years. [mpifr-bonn.mpg.de]

      So supernovas have happened in our local bubble, and evidently quite close.
      • Mmm. The nearest one from that association is ~500ly away. In my humblest of opinions that makes this theory pretty far-fetched, even if they've been moving away from as at a very high rate for the past few million years. Remember, they say that Antares poses no danger, and it's only 500-600ly away too.
        • Re:Inane (Score:2, Informative)

          by snowlick (536497)
          This article [sciencenews.org] points out that some stars in the cluster could have been as close as 130 light-years away around 2 million years ago. The local bubble itself is only 150 light-years across, so the earth would have been within the necessary range for damage to occur.

          There's also a theory [aas.org] floating around that a star in the cluster actually made the local bubble.

    • Re:Inane (Score:1, Interesting)

      by Anonymous Coward
      it's not so ludicrous. Stars travel, and millions of years ago there could have been some stars "passing through" and now the remanents of the supernova could be relatively far away. I think their Antares figure is a typo though, isn't our galaxy only 100,000 lightyears across? And besides, no normal star in our galaxy is moving fast enough, relative to us, to cover 500,000 lightyears in only a few million years.

      my $.02
    • Re:Inane (Score:3, Informative)

      by cp99 (559733)
      Perhaps you should read the article [lanl.gov] (the scientific paper that is, not the CNN article) before dismissing it as "insultingly ludicrous."

      The local bubble is thought to have formed approx. 10 million years ago, not 5-6 billion.

      The paper also references works that show that the various subgroups which make up the Scorpius-Centaurus OB association, have produced plenty of supernova's in the past.
    • Not Inane (Score:2, Insightful)

      by tm2b (42473)
      If a star supernovaed as it passed us, the remnants would have on average roughly the same velocity as the star group - they would also be 500,000 light years away now.

      I doubt CNN made this story out of full cloth, I'm sure the theory has more to back it up than CNN reported - it's not like CNN is a scientific journal, they always trim corroborating details.

      (Frankly, I think it's absurd that this comment was moderated to the top.)
    • Re:Inane (Score:2, Interesting)

      by shimmin (469139)
      Just because we are in an interesting position in the galaxy now doesn't mean we have been there for any more than a few hundred million years.

      Gravitational "mixing" of the galaxy ensures that a star can travel from pretty much any part of the disk to any other part within about a billion years and that our present stellar neighbors were not our neighbors for most of our history.

      Basically, we have no clue where in the galactic disk the sun formed, nor which supernova remnant is responsible for seeding the sun's formation, nor the location of most of the nearby objection in the galaxy more than a billion years or so ago.

  • When they say "wreak havoc" on terrestrial life I wonder what the extent really could have been..
    ( more data! )

    If there was a mass irradiation, it might give some more explanation to the mass extinction that happened at the end of the Devonian period that basically cleaned out most of the diverse sea-life ( there wasn't much on land those days )
    Of course, someone please tell me if I have my time-periods wrong, I'm no geologist..

    Ideas?
  • Note that, the article claims that the next star in that cluster expected to go supernova is 500,000 light years away.

    Of course, it also claims that that star is Antares, which is actually about 600 light years away.
  • 500000 light years? (Score:5, Informative)

    by MillionthMonkey (240664) on Monday March 11, 2002 @02:17AM (#3141329)
    From the article:
    The next member of the gang expected to go supernova is Antares, which at almost 500,000 light-years away is too distant to rattle our planet, they say.

    What kind of dope are these astronomers smoking? Antares is 500 light years [nasa.gov] away.

    Still quite distant, but 500000 light years will place you well outside the Milky way. It's about as far as the Magellanic clouds.
    • by Ellen Ripley (221395) <ellen@britomartis.net> on Monday March 11, 2002 @02:26AM (#3141363) Journal
      What kind of dope are these astronomers smoking?

      CNN was smoking the dope. Other sources reported 500 light-years. :-)

      Ellen
    • What kind of dope are these astronomers smoking? Antares is 500 light years [nasa.gov] away. Still quite distant, but 500000 light years will place you well outside the Milky way. It's about as far as the Magellanic clouds.

      My boss must be smoking same kind of dope. The Y2K problem became Y2000K in his management summary - Man this guy is really thinking ahead!
  • More fodder for the pseudo-science of denying the existance of global warming.

    Amazing. Global warming and Ozone depletion in 70 billion B.C. was caused by a SuperNova. Global warming in the 1970's was caused by the Chevy Nova.

    Why does Michael Jordan want to see your underpants? [lostbrain.com]

    tcd004

  • So if this hadn't occurred, would we all have flying cars and eliminated world hunger and learned to all peacefully coexist by now? How far back did this set us..
  • Effect on evolution? (Score:5, Interesting)

    by cybermage (112274) on Monday March 11, 2002 @02:19AM (#3141339) Homepage Journal
    Makes you wonder if we're here to discover it happened because it happened.
    • by Anonymous Coward
      when you... think about how the universe was made... it's the universe thinking about itself.
    • Makes you wonder if we're here to discover it happened because it happened.

      No, it doesn't. Take as many apes as you please, put them in a dirty nuclear reactor and wind the dial up to `Max' for a few days and see if they evolve at all.

      There's a reason you wear a lead coat when you go to have your insides xrayed - and the technician stands behind another lead screen - and it's not the risk of becoming too smart for your family to bear.
      • Re:Over-reactoring (Score:3, Interesting)

        by lohen (122373)
        True, an induced higher rate of mutations does not tend to lead to an increased rate of evolution (unless it be towards radiation tolerance) since the vast majority of mutations are silent or disadvantageous. But this would have influenced evolution nevertheless, simply by killing a load of creatures and creating turmoil in the ecosystem, leading to a period of rapid change and differing evolutionary pressures.

        Evolution occurs primarily in response to outside influences of the time, rather than towards any particular goal. Asteroid impacts, volcanic eruptions, and now apparently (although IANA astronomer, and mistrust CNN) supernovae all have a bearing on how things have turned out today.

        • And maybe that's the best reason to think that it didn't happen (or CNN fouled up the time scale, like they fouled up the distance to the next possible supernova): IIRC the fossil record does not show unexplained or sudden massive extinctions in land animals 2 million years ago. This was an ice age, so the climate was highly variable, and this did influence evolution by frequently changing the evolutionary pressures. This would have pushed evolution towards the more versatile types -- say a smart bipedal ape that can figure out how to survive when the climate keeps flipping back and forth between extremely wet and semi-desert every few generations.

          Phytoplankton get some radiation shielding from the water, so a supernova that hit hard enough to kill 40% of them would have killed many more land species, and I don't recall anything like that. The big extinctions were either earlier (presumably when the Ice Age was starting) or later (when the bipedal apes started killing large animals with sharp flakes tied to sticks.) Especially, I don't recall any massive plant extinctions (land plants would be the most vulnerable) which aren't related to climate changes.

          Note also that most humanoid fossils have been found in the Great Rift Valley, where Africa was being ripped apart 2 million years ago. Geological change might have accentuated the evolutionary pressure towards smart and adaptable. Or it may be that Australopithecus was evenly distributed all over Africa, but was generally smart enough to avoid the sudden burials that form most fossils. The Great Rift Valley had plenty of volcanic eruptions and flash floods, so the only way intelligence would have kept any species non-fossilized was by living somewhere else. It might explain a few things if the Leakeys are digging up the bones of the losers who had to live in the most undesirable real estate in the continent, rather than the more successful forms of early man...
          • a supernova that hit hard enough to kill 40% of [Phytoplankton] would have killed many more land species, and I don't recall anything like that.
            Man, you must have some memory!

            it may be that Australopithecus was evenly distributed all over Africa, but was generally smart enough to avoid the sudden burials that form most fossils.

            I am not a Paleontologist (in fact I can't even spell it), but it seems to me that land species getting caught in circumstances conducive to producing fossils was the exception rather than the rule. And not only did conditions have to be just right to form fossils, but conditions from that point on had to be conducive to not eroding the fossils back into dust.

            While we have substantial fossils going back to the Neanderthal era, I think the total number of sites where hominid specimens older than 1 millions years have been found can be counted on both hands [talkorigins.org].

            So to make any inference as to whether or not any specific environmental event made a noticable change in the evolution of hominids that long ago, is anybody's guess. However, the earliest member of the genus Homo, Homo habilis did appear just about 2 million years ago. Though various Australopithecus species continued to exist in parallel with the Homo species for several hundred thousand years after that.

    • Huh? Evolution happens, period. It doesn't require supernovae or comet strikes or asteroid impacts. Such events merely act to change the course of evolution as it was situated at the time of the event.


      Dinosaurs weren't static and unchanging, they were evolving just like everything else. Their evolutionary history merely came to an end with the probable K-T asteroid impact. It that hadn't happened, we would not be here but some other form of life would be - different dinosaurs or something else. Not necessarily (by ANY stretch) technically advanced life as we fashion ourselves, but something other than what is.


      Evolution just happens. Its fortunes can be altered for any given species or genera, etc, by some catastrophic event but don't make the mistake of thinking that such episodes are required for evolution to happen.

    • Makes you wonder if we're here to discover it happened because it happened.

      It also makes you wonder if this kind of thing is common enough that it tends to take out intelligent races before they develop interstellar travel.

      Or if it might make interstellar travel at sublight speeds sufficiently hazardous that there isn't much of it.

      Or perhaps the cluster has made this region sufficiently dangerous that nobody has come here recently (like in the last few million years).

      Any (or a combination) of these might help to explain why, as far as we can tell, no little green men have dropped in to visit.
  • If the life is gone then how can we verify that it even existed at all?? Kind of like saying 100 unknown species of animals go extinct in the rainforest every day...
    • "If the life is gone then how can we verify that it even existed at all?? "

      You are so right. And to think of it until recently i believed the lies scientists told me about dynasours roaming the earth.

    • by cp99 (559733)
      Because all of a sudden, their fossils stopped appearing in the geological column.
      • Because all of a sudden, their fossils stopped appearing in the geological column.

        And here's me thinking that fossils of practically everything appear and disappear abruptly in the fossil record. Now where on earth did I get that silly idea? Oh, yes: Earnst Mayer, Stephen Gould, Niles Eldredge, Richard Goldschmidt, Roger Lewin, and let's not forget Charles Darwin. Sounds a bit like a who's who, dunnit?

        Ergo: non sequitur.
  • Hmm... Could mass radiation have done something to life forms today? We always hear about our odds of being a planet with life. First our distance from the sun and then the fact that it gives out lower then average radiation. Is the time frame right for creating the "missing link" or just plain skipping it? As you can tell, I'm no biologist.
  • It's a space station!
  • They talk about this showing up in the marine fossil record, but what about on land? The article mentions some geological data, but is there any on-land paleontological evidence to support this? Also, they only talk about it killing plankton - does that mean that it was too far away to kill anything larger directly? Perhaps this is why we haven't run across it in any other fossil records...
  • I personally think this was the accident that killed off all the smart proto-plasm.

    Anyone else with me on this hair brained idea?
  • Time (Score:1, Interesting)

    by radoni (267396)
    When exactly *is* 500,000 years? let's say that the next-nearest Nova goes off somewhere in a galaxy far far away. the actual light wouldn't reach for half a million years?

    I'm sure this is rocking a dead baby, but how do the "experts" signify exactly *when* things happen, and what specifically that means. Do the anomolies happen and are observed later, the event of which is estimated in reverse?

    Does this mean if i put instant coffe in a microwave, i'll go backwards in time?

    • Well firstly like others have pointed out, Antares is nothing like 500,000 light years away. That's a 1000-fold error and lazy journalism on CNN's part.

      As for when it's going to happen, the stellar time scale is so big compared with what we're used to that it really comes down to a guess. This is figured out based on studying other stars and coming up with theories about the life cycles that they follow... and the theories are always being revised and revised and revised as more information pours in.

      Antares is a red giant star that's used up all it's hydrogen, and now it's fusing together heavier and heavier elements, and starting to run out. It might die tommorrow or it might die a million years from now. All that's known at the moment is that it's very near to the end of its life cycle, and that it's massive enough such that when it dies it'll likely go out with a very big bang, probably about as bright for a while as the rest of the Galaxy put together. (We see this happen with stars in other galaxies every so often when an unknown star that couldn't be seen individually suddenly lights up out of nowhere.)

      Nobody knows exactly when it'll happen, though.

    • Well actually you're facing the same problem many have whith special relativity. (including my prof. :o): To realize that there is not one "true" universe where space and time counts, but every point sees (or even has) it's own universe.

      Well in the non existing global universe you could say that the star exploded 500,000 years ago, but this view is irrelevant. For us 500,000 light years away, the star explodes "right now" in the moment we see it's flashlight. Or receive a massive neutrino impact the day before. (Thats not because neutrinos travel faster than light! But because the star stars sending them a day before it explodes.)

      Again every point has it's own universe. You can feel it mathematically if you take two equations, which hold both true but for two different obversers and substitute them toghether, you get math. nonsene like 1=2. Thats because bath equations may be true, but not in the same "universe". As Einstain proofed this even goes further, as there isn't even global simultaneousness, things that way happen synchron for one observer, way be seen in sequence by anoter observer, or even in reverse sequence by yet another observer.

      • Blockquoth the poster:

        Or receive a massive neutrino impact the day before. (Thats not because neutrinos travel faster than light! But because the star stars sending them a day before it explodes.)

        I thought the discrepancy came from the fact that neutrinos pass through matter much more easily than light, which needs to bounce its way clear.
  • Does anyone know how far away the cluster was at the time of the alleged nova? I googled around but couldn't find that figure.

    Ellen
  • "500,000 light-years away and is too far from the earth to cause any damage." Thanks for the double clarification, I knew my studies astrophysics class wouldnt last!
  • I was just wondering how much of this is tied to the neodarwinian theory of evolution. Doesn't that theory have circular dependencies with the fossile record? I've also heard a lot about errors in radiometric dating and stuff like that, but I have yet to fully look into it.

    Anyway, how much of this story is influenced by the idea of evolution, and how would the story read if fallicies were found in the NDT?

    • The fossil record is "tied to" Darwinian theory only in that the latter is the most successful explanation of the former. Fossils are found things, not theoretical constructs. Determining their sge depends a lot on physics (through radioactive dating) but only weakly, if at all, on biology.
      • Pi in yer eye! (Score:3, Interesting)

        by leonbrooks (8043)
        Fossils are found things, not theoretical constructs.

        True, but you left out a pivotal part of the story: what happened to them and when is a theoretical construct.

        Determining their [a]ge depends a lot on physics (through radioactive dating) but only weakly, if at all, on biology.

        Now that's just completely wrong. Biologists extracting blood cells from T-Rex bones can get a fairly good idea of an upper limit for the bone's age, based on home much the organic material has decayed. And it's shy at least four noughts of any figure you're likely have in mind. (-:

        Of course, when people dig up fresh dinosaur bones, or extract fresh wood from within Manley sandstone, that generally presents them with a pretty big hint about the age of what they've found. But, of course, the false assumptions undergirding this assertion...

        The fossil record is "tied to" Darwinian theory only in that the latter is the most successful explanation of the former.

        ...are so important on philosophical/metaphysical grounds that inconvenient observations like those tend to just get swept under the carpet.

        I think the pi in your post is a sign from the gods of science that you're making them do too many beetles, and you need to step outside of your reality bubble for a while so they can discuss things with you. (-:
        • Blockquoth the poster:

          Biologists extracting blood cells from T-Rex bones can get a fairly good idea of an upper limit for the bone's age, based on home much the organic material has decayed.

          The only dating method using how "much the organic material has decayed" that I know of would be radiocarbon 14 dating. C14 has a half-life of about 5000 years, so it cannot be used reliably for more than, let's say, 10 iterations. (That would be one part in 1000, approximately.) That puts its usefulness back to maybe 50,000 years. We can increase the accuracy by about a factor of 1000 and still only push back that date by a factor of 2 (to 100,000 years).


          Worse still, the whole "dating" part depends on assumptions of the constancy of the ratio of C14 to C12, which have to be taken more or less for granted.


          However, dating of really old fossils comes from dating the rock in which they are found. These inorganic methods use other radioisotopes, and can be reliable all the way out to 4 billion years, with no necessary assumption about constant abundances. So these methods, which are nearly armchair physics, establish the geological age of the Earth.

          • Biologists extracting blood cells from T-Rex bones can get a fairly good idea of an upper limit for the bone's age, based on home much the organic material has decayed.

            The only dating method using how "much the organic material has decayed" that I know of would be radiocarbon 14 dating.

            I recommend extending [dinoos.nl] your [bearfabrique.org] education [christiananswers.net] before pontificating. (-:

            I'm not talking about C14, I'm talking about meat, bone and blood cells.

    • These finds are unrelated to the theory of evolution. The theory of evolution is one of sciences most impressive theories which has withstood attacks both fair and foul. The basic theory doesn't rely on super nova's millions of years ago.

      The theory of evolution doesn't have circular dependencies on the fossil record. That's just creationist wishful thinking.

      When you mention errors in radiometric dating, do you refer to the unaccuracies that science knows and accounts for, or do you refer to delibrate misuse of radiometric dating by Steve Austin (the creationist, not the wrestler)?

      If NDT was incorrect, the science behind this (ie. supernova ~2 million years ago killed off lots of marine life) would still stand.
      • The theory of evolution is one of sciences most impressive theories which has withstood attacks both fair and foul.

        Not so much `withstood' as `denied and papered over the wounds from'.

        This consists very much of closing one's eyes and crying `It *IS*, dammit!' - only it's generally done professionally and en masse (cf Wistar and similar conferences).
        • by cje (33931)
          Not so much `withstood' as `denied and papered over the wounds from'.

          Ah, yes! The evil, black-helicoptered Scientific Orthodoxy! An army of jack-booted, blue-helmeted thugs, commanded by Persian-catted evil overlords in their concrete fortresses on the far side of the moon. They are coming for us. They are coming for us all.
          • Ah, yes! The evil, black-helicoptered Scientific Orthodoxy! An army of jack-booted, blue-helmeted thugs, commanded by Persian-catted evil overlords in their concrete fortresses on the far side of the moon. They are coming for us. They are coming for us all.

            Well, no. All that needs to happen, and it often does without specifically evil intent, is for papers [i5ive.com] to [visi.com] go [direct.ca] unpublished [answersingenesis.org] often [aaas.org] enough [rae.org]. And evidently they do.
  • by Alien54 (180860) on Monday March 11, 2002 @02:38AM (#3141405) Journal
    500,000 light-years away

    The Galactic core is closer than that, the last I checked. Andromeda is about 2 million LY away, if I recall right. Let's see.

    Antares = 520 light years [seds.org]

    CNN cites the Scorpius-Centaurus OB Association [mpifr-bonn.mpg.de] of stars which is actually about 470 light years away [mpifr-bonn.mpg.de].

    So CNN was off only by a factor of a thousand. Interesting theory, if they can get the facts right.

  • by jsse (254124) on Monday March 11, 2002 @02:38AM (#3141407) Homepage Journal
    Researchers have always worried about there might be in fact a single cause of Mass Extinction [bbc.co.uk]. You can refer to this graph [tulane.edu] for the rough interval of mass extinction.

    Most people believe that the meterorite impacts [tulane.edu] is responsible for the mass extinction, but now this new findings may sparks a new way of thinking - the murderer may be someone else.

    If we believed that there's a cycle for Mass Extinction, there we don't have much to worry about - as it's still millions of years away. However, some people also believe that the Sixth Extinction [well.com] might come earlier, because human was not present in the last 5 extinction, and that makes the great difference.

    Thank you for reading my trolling. I quote as much online reference as possible, but actually my point of view are from the books I read. My apology.
  • Sorry, I only read the headline and thought it was about the cultural damage cause by Elvis' exploding weight and ultimately his death. Would probably have made for a more interesting read.
  • by Waffle Iron (339739) on Monday March 11, 2002 @03:01AM (#3141452)
    Since most of our bodies' mass is made of elements heavier than helium, we've all been inside at least one supernova explosion. Things have really quieted down around here since those days.

    I don't even want to contemplate how much energy was given off forming the elements I'm made of. Now there's hardly enough energy left over for me to get up and fetch another beer.

  • by jquiroga (94119) on Monday March 11, 2002 @03:01AM (#3141453)
    Please read the paper [lanl.gov] before dismissing the theory.
  • > But don't worry about it happening again
    > anytime soon. The next expected supernova is
    > nearly 500,000 light-years away and is too far > from the earth to cause any damage."

    Man, you had me going there for a minute. I was getting pretty worried, but I'm glad you straightened it all out for us in the end :-)
  • Must of been a supernova that caused CNN, AOL-TW, M$, the MPAA...
  • by abolith (204863)
    like a new supernova is the ever-present worry on my mind.....
  • "The next expected supernova..."
    You can expect these things?
    • by foul (89373)
      I havent read the article, shoot me ;-) But my guess is that they just look for the most massive star in the solar neighbourhood. The reasoning is:

      1) a star can only use about 10% of the available hydrogen, before more rapid evolutionary mechanisms set is (ie before some of them go boom)

      2) only 0.7% of the rest mass energy is turned into energy

      3) the relation between luminosity (L) and mass (M) is:

      - M proportional to L^4 (for massive stars)

      Thus nuclear time scale (tn):

      tn = 0.007*0.1*Mc^2/L ( = 10^10 year for the Sun)

      for other massive stars:

      tn = (M/Msun)/(L/Lsun) * 10^10 yr

      = (M/Msun)/(M^4/Msun) *10^10yr

      = M^-3 * 10^10 yr

      so if one would find a 10 Msun star nearby, you could expect it to go boom in 10 million years. In other words, a cosmic 'blink of the eye'.

      • Short version of above: once a large enough star leaves the main sequence, you can come up with an order-of-magnitude guess as to when it will blow. This guess, by the way, would likely be expressed according to observed time (i.e., our time), not absolute time.
  • This is what happens when you get science news from CNN. Antares IS NOT 500,000 ly away; it is 600 ly away. Big difference. As well, one cannot say that it is the "next expected supernova". It's a good candidate but so is Betelgeuse for that matter. Eta Carinae is much mre likely to go supernova than either of them.
  • Badastonomy.com (Score:3, Informative)

    by StarTux (230379) on Monday March 11, 2002 @04:48AM (#3141671) Journal
    best place to lay any media inaccuracies to rest.

    here it is again, www.badastronomy.com

    Although no-one has mentioned it on there bulletin board yet. Real astronomers visit this board, indeed a real one runs it.

  • by sunspot42 (455706) on Monday March 11, 2002 @04:59AM (#3141696)
    This star group the article refers to is around 500 light years away, not 500,000. Next time, CNN should assign this "reporter" to cover trends in hairstyles or sightings of Elvis or some other topic the "reporter" might be capable of understanding.

    Or maybe this is just another example of Time Warner math coming from CNN's parent, the same arithmetic that shows the record studios to be losing billions of dollars due to music "piracy". The multiples are probably similar in both instances.
  • by Veritan Drelor (468345) on Monday March 11, 2002 @05:03AM (#3141703)
    This all possible, yes, but it's also extremely unlikely.

    First the possible. A quick, back of a napkin calculation shows that a supernovae at around 3 light years would appear roughly as bright as the sun (depending on the circumstances). A good opprtunity to work on your tan, for a few days anyway. Nothing to really worry about, but if you're skinned, slap on some SP-40.

    Now, if it's much closer, you might have some problems. At ~1.5 light years, the supernova is 4 times as bright as the sun, and at ~1 light year, it's 9 times as bright. Hooray, we know what an inverse square law is.

    The real problem is this: there aren't that many stars nearby. The closest, Proxima Centauri, is 4.2 light years away. And there's no chance of it ever going supernova - only comparatively massive stars manage that. Within 10 light years of us, there are only 12 stars (and that includes Sol). Of those there is only one that's ever going to go supernovae - Sirius, at a distance of 8.6 ly. And that's an exceptional case. You have to go to the 70th nearest star before you find another star in the same situation - Altair, at 16.8 ly.

    Now, even with Sirius and Altair, they're going to be shining for millions of years to come. Now, what they're suggesting is that one of those really rare large stars just happened to be really close to us when it's lifetime of tens of millions of years came to a close. Right.

    Time for those astronomers to come down from the mountain - the altitude seems to be having an effect.
    • Your proof by induction isn't complete. You said that the chance of an exploding supernova affecting life here on Earth is very unlikely, but you only gave *currently-existing* stars as an example. I mean, if a star turned into a supernova ages ago, that star would be dead by now (and hence not mentioned in the "Guiness Book of Closest-Star Records" or whatever the astronomers call it), right?

      And the scientists just found evidence that this supernova might have existed before, in the form of those unusual iron samples on the ocean floor.

      At least give them credit for that. Your sarcasm doesn't prove anything except that you're cynical. =)
    • The increased brightness, even for a few weeks, will cause problems with the weather. Not just the fact that days or nights will be much warmer (depending on where the SN appeared), but the changes in air circulation, evaporation, etc.

      But that's not the killer. The killer is the nebula that will hit years after the light (and cosmic ray) flash. It has a lot of mass (relatively speaking) and is moving fast. If we're lucky, it just destroys the ozone layer.
  • ..wreaking havok..

    Thanks for the nod, but I think you meant havoc [dictionary.com]

    Unless, of course, you've slipped into your Middle English Ultima character :)

  • To paraphrase the article a little more accurately than CNN, I hope.

    There is a cluster of young bright stars, currently about 500 ly away from us. They analyse the known movements of cluster (and the Sun) and the likely rate of supernovae in the cluster over the last 5-10 million years. They conclude that there could very plausibly have been enough supernovae from that cluster to account for two things:

    1. The "local bubble" a region of space about 500 ly in radius containing the Sun in which the usual interstellar gas is much hotter and thinner than usual.

    2. The unusually high levels of a stable, but rare
    isotope of iron in seabed sediments laid down at certain times.

    The rule out various mechanisms that might have stopped the iron from the supernovae reaching the Earth.

    They look, much as an afterthought at the possible biological impacts of these supernovae. These are not strong, and I would not say that the paper
    really supports the idea that this is the trigger
    of any mass extinctions. The closest of the supernovae would, apparently significantly reduce
    ozone levels in the stratosphere (charged particles from the SN catalyse NO formation, which
    destroys ozone), and this would increase levels of
    UV-B at the surface, to which plankton and corals
    are especially susceptible, so there might have been some extinctions there, but that seems to be all.
  • How do most people think that the heavier elements ended up in this system anyway? Think about it. You need a star of at least 8 solar masses to start the r-process, the rapid heavy-element formation process. There just isn't enough mass in the solar system to account for that. There must have been another close encounter billions of years ago that allowed a young star to "rip" enough material from an old supernova remnant /dense cloud to form the planets with the elements we have today.

    nahtanoj

    • I thought the latest idea was the the really heavy elements formed in neutron star collisions, which spray them out at close to light-speed in jets. Rare events, but they produce and scatter a lot if heavy elements, which are not all that common anyway.

      • These elements are formed as the >= 8 solar mass stars collaspe into neutron stars. The shockwaves of the collaspe initiate the formation of the elements. I don't know about the jets, but you might be right.

        nahtanoj

  • by NormalVisual (565491) on Monday March 11, 2002 @09:49AM (#3142204)
    It probably should be clarified that the statement about Antares being the next probable supernova really meant "Antares is the next likely SN candidate in that cluster". For quite some time, astronomers have been keeping an eye on Eta Carinae, which is about somewhere between 7.5K and 10K light years away, but could possibly let go at any time. It will likely be quite harmless except to astronauts and orbiting spacecraft (there is some discussion regarding whether it could become a gamma ray burster), but quite spectacular to see. There just aren't any sufficiently massive stars close enough to us to really worry about supernovas anytime soon.
  • Alright, I'll put the catalytic converter back on my nova. Geez, who'd a thought one chevy nova would cause that much of a stir?
  • "The next expected supernova is nearly 500,000 light-years away"

    That's a neat trick, considering that the Milky Way is only about 100,000 light-years across...
  • by xihr (556141)
    Here's [rit.edu] an analysis of the risks associated with nearby supernovae. The executive summary is that gamma rays offer the most potential for destruction, and the danger range is within about 100 ly.
  • So me live in a supernova hole/bubble?

    Is it possible that only in these areas of the glaxies suns have a planet system? The elements we all consist of are after all just supernova exhaustion.

    Maybe there are far less planet systems than we have expected?

The universe is like a safe to which there is a combination -- but the combination is locked up in the safe. -- Peter DeVries

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