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Earth Space Science

What Struck Earth in 775? 344

Posted by samzenpus
from the park-that-anywhere dept.
ananyo writes "Just over 1,200 years ago, the planet was hit by an extremely intense burst of high-energy radiation of unknown cause, scientists studying tree-ring data have found. The radiation burst, which seems to have hit between 774 and 775, was detected by looking at the amounts of the radioactive isotope carbon-14 in tree rings that formed during the 775 growing season in the Northern Hemisphere. The increase in 14C levels is so clear that the scientists conclude that the atmospheric level of 14C must have jumped by 1.2% over the course of no longer than a year, about 20 times more than the normal rate of variation (abstract). Yet, as the only known events that can produce a 14C spike are supernova explosions or giant solar flares, and neither event was observed at the time, astronomers have a cosmic mystery on their hands."
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What Struck Earth in 775?

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  • by eldavojohn (898314) * <eldavojohn.gmail@com> on Monday June 04, 2012 @08:51AM (#40207591) Journal
    You need only look at the years leading up to 775 to unravel this mystery. In 773 [wikipedia.org] at the start of the Islamic Golden Age, the number zero was introduced to Baghdad which would, in 775 [wikipedia.org], surpass China's capital of Chang'an as Earth's largest city. Now, we know from the second law of thermodynamics [wikipedia.org] that 'the entropy of an isolated system that is in equilibrium is constant.' Now with all those people suddenly using zero in tons of transactions and writings, Earth experienced a huge decrease in entropy. I'm sure if you analyze the existing works from the time, you'll find that pervasive use of the hot new number zero increased the frequency of numbers at the time by 1.2%. That means that somewhere there had to be an increase in entropy to maintain the balance described by the second law of thermodynamics. Of course, anyone with a mail-order internet degree can tell you the obvious natural source of entropy at the time would be the decay of nitrogen-14. What? Falsifiability? Just watch, the floods in Thailand have lead to a decrease in production of ones and zeros hard drives which means we'll finally get a break from this 'global warming' or (let's just call it for what it really is) the 'entropic energy extravaganza!'

    Also, for good measure: Nazis.
  • by MyLongNickName (822545) on Monday June 04, 2012 @08:53AM (#40207603) Journal

    I don't have a comment other than to say that I enjoy articles like this one. Please bring more like it and i will hit refresh 20 times to get yor page hit count up :)

    • by belthize (990217) on Monday June 04, 2012 @08:58AM (#40207665)

      I don't know, I've read the article and it's still not clear to me whether an iPhone or Android is better, who to vote for, whether I should be mad at banks and who to vote for.

      On a more serious note, I wholeheartedly agree.

      • by Anonymous Coward on Monday June 04, 2012 @09:31AM (#40207991)

        I don't know, I've read the article and it's still not clear to me whether an iPhone or Android is better, who to vote for, whether I should be mad at banks and who to vote for.

        Whether an iPhone or Android is better: Yes. While both iPhones and Android phones also emit radiation, that radiation is for sure less harmful than the high-energy radiation from this event.

        Who to vote for: It was an event of huge radiation. Radiation is bad, so to prevent such radiation in the future, you should vote for the Green: Since they are against radiation, they will certainly make sure that such a disastrous event (so disastrous that even the records about it got destroyed!) won't happen again.

        Whether you should be mad at banks: Banks usually have security personnel, therefore being mad at that place might not be a good idea. On the other hand, if you are a danger to yourself when going mad, it may be a better idea to be mad at a bank than when alone at home. Just make sure it's not your bank you get mad at, because they might not let you in again afterwards.

        Who to vote for: Well, this was possibly caused by solar flares. Now the Green are all for solar energy, which, as this event shows, is not without danger. Therefore you should vote for anyone but the Green.

        SCNR :-)

        • by stanlyb (1839382)
          Maybe their Obama decided that the treat of Chingiz Han is too big, and wanted to protect his country by using the well forgotten and useful TSA agency, which resulted the before mentioned peek in radiation..... And after that, silence, of the lambs.
    • Re: (Score:3, Insightful)

      > I enjoy articles like this one. Please bring more like it.

      You want more articles about huge things hitting the Earth?!?!??

      I'd just as soon there be not much to write about.

  • Lavos (Score:5, Funny)

    by shiftless (410350) on Monday June 04, 2012 @08:53AM (#40207605) Homepage

    Is that you?

    • By total coincidence, I just came here from ordering the CT remake on DS. Apparently this cosmic ray burst happened to make me feel special today.

  • Behind the Sun? (Score:5, Insightful)

    by Maximum Prophet (716608) on Monday June 04, 2012 @08:54AM (#40207613)
    If the supernova was behind or near the Sun, earthlings around 775 wouldn't have been able to detect it.
    • Re: (Score:3, Informative)

      by Anonymous Coward

      If there was a supernova around then, then there would be remnents of a supernova that we could date back to then, right? We would be able to observe the remnents today and work back to about when that particular star died, even if it wasn't observed back in 775, right?

    • by forand (530402)
      Two problems with your hypothesis: 1) if the Earth was hit by a huge burst of radiation coming from the direction of the Sun it would have been recorded as a solar flare or something odd. 2) There would be remnants of such a nearby super nova clearly visible now and most assuredly in the months immediately following the event.
      • Re:Behind the Sun? (Score:5, Insightful)

        by Lumpy (12016) on Monday June 04, 2012 @09:37AM (#40208035) Homepage

        You cant see a Gamma Ray burst. Sorry the real world is not like SCI-Fi.

        And no, they would not see it. Can you see ANY nebula in the night sky with your eyes? there are several that are LARGER than the moon up there if they were visible to the eye, but require a camera to show them, something that did not exist back then. Supernovae dont stay lit in the sky for a very long time they fade out to below human visibility within a short time and if it was close to the viewing line of the sun, Nobody would have ever seen it even if it was Lit up for a few weeks..

        • Re:Behind the Sun? (Score:5, Informative)

          by smooth wombat (796938) on Monday June 04, 2012 @09:45AM (#40208095) Homepage Journal
          Can you see ANY nebula in the night sky with your eyes?

          Yes, there are. Orion, Pipe, Eta Carinae and Coal Sack are four you can see with the naked eye. Granted, the people back then wouldn't have known they were nebulas, but those objects were still visible in the night sky.
        • Re:Behind the Sun? (Score:5, Informative)

          by bigrockpeltr (1752472) on Monday June 04, 2012 @09:57AM (#40208219)
          M42 (Great Nebula in Orion) is clearly visible with the naked eye even in fairly light polluted areas. Also, people have reported seeing at least one supernova with the naked eye from back in those days when light pollution was essentially zero. but you are right about not being able to notice a SN if it was only visible during the day.
          • Re:Behind the Sun? (Score:4, Informative)

            by Lumpy (12016) on Monday June 04, 2012 @10:46AM (#40208781) Homepage

            Unfortunately M42 is not visible from around here, and most people cant spot it until it is pointed out, even in low light pollution areas. People in general dont notice. But the trained eye certainly can, like you point out.

            But, IT would have to be brighter than -2.5 to be seen from Earth during full daylight. Anything near the sun within several sun widths would have to be ungodly bright to even be noticed. Even during a 2 month period a close supernovae would be unnoticed. The could would not stay at -2.5 for very long, so even if it was a super bright -1 it would be close to 6 months before it would swing around into twilight.

            You could have a 4.5 month period of not being able to see it. Plenty of time for a distant one to dim considerably.

        • by mrsquid0 (1335303)

          One cannot see the gamma-ray part of a gamma-ray burst, but one can see the afterglow, and afterglows can be very bright. A typical optical afterglow from a gamma-ray burst lasts for several days, and can be brighter than a supernova. If a gamma-ray burst did cause this burst of radiation then it is quite reasonable that the optical afterglow would have been seen. However, if the burst did occur behind the Sun then, because the afterglow fades very fast, it is possible that the afterglow would have faded

        • Re:Behind the Sun? (Score:5, Interesting)

          by forand (530402) on Monday June 04, 2012 @10:21AM (#40208491) Homepage

          If a GRB went off in the Galaxy then a few years of increased radioisotopes would be the least of the indicators. A mass extinction would be associated with such an event as most of the ionosphere would be striped from the Earth causing cosmic rays to reach the surface, this would have dramatic and lasting effects on life. I also neither implied nor stated that this was associated with a GRB.

          While supernova do not "stay lit in the sky for a very long time" you need to scale that with your time scale of the event. The Crab Nebula is the result of a supernova that went off in 1054 [wikipedia.org] (Earth time) and was visible to the human eye for a period of approximately 2 years after it went off. There is no associated increase in radioisotopes for that event, thus indicating that a larger (likely closer as well) event would have to be the cause of the increased radioisotopes observed in 775.

          • by Lumpy (12016)

            And if it was in line with the galactic disc it can easily be hidden from the dust and all the light pollution from our galaxy, Very good point.

        • by CptNerd (455084)

          Gamma rays wouldn't form C14, only neutrons that got caught in the nuclei.

    • by siddesu (698447)
      Two problems with that theory - a supernova close enough to cause a radiation spike would probably still be visible by the time the Sun moved out of the way, and in 775 someone would have noticed it. Even if it was far enough so it wasn't, the remains would still be very obvious -- it ought to have been much closer than the Crab Nebula remnant (6.5k light years, assploded in 1050 or 1060), and even I have seen that.
    • Re:Behind the Sun? (Score:5, Informative)

      by pla (258480) on Monday June 04, 2012 @11:10AM (#40209055) Journal
      If the supernova was behind or near the Sun, earthlings around 775 wouldn't have been able to detect it.

      Nearby supernovae appear as one of the brightest objects in the sky for a few days to a week. The remnants remain visible for months, and then have a habit of leaving a nebula behind.

      The Earth travels slightly more than one degree of its orbit per day; The Sun, as seen from the Earth, subtends half a degree of arc. In the absolute worst case, the sun couldn't completely "hide" a supernova for more than a single day; and half a week later, the supernova remnant would dominate the dusk (or dawn) as the brightest thing in the sky except possibly the moon.
      • by pla (258480)
        The Earth travels slightly more than one degree of its orbit per day

        Mea culpa - make that slightly less than one degree per day.
  • by Anonymous Coward on Monday June 04, 2012 @08:55AM (#40207625)

    Would this mean carbon dating is inaccurate for items older than 1300 years?

    Time to redate the Shroud of Turin?

    • by h4rr4r (612664) on Monday June 04, 2012 @09:04AM (#40207733)

      Why do we care when a poorly made fake was made?

      Your first question is more interesting.

    • Not it just means an adjustment to c14 dating. It would not affect the shroud of turin, since it is clearly from well after 775.
    • by vlm (69642) on Monday June 04, 2012 @09:23AM (#40207911)

      Would this mean carbon dating is inaccurate for items older than 1300 years?

      Things that were alive in 775 appear to have more C14 than usual, so even after centuries of decay, they'd still have more C14 than usual, which would make them measure younger. This is my understanding from reading the "Amateur Scientist" column in "Scientific American" about doing radiocarbon dating at home. SciAm used to be a pretty cool magazine, well, 50 years ago. When I was a high school kid I spent about two weeks one summer reading on microfilm pretty much every Amateur Scientist column from the 30s (when it was all telescopes) until the 70s when it started sucking. You can buy a collection of those columns on a cdrom now, of course.

      Time to redate the Shroud of Turin?

      I'm not up on my mythology, but I think it's made of woven plant or animal fibers, and this would have no effect unless the plants or animals that made it were alive in 775. If it was grown in 775, then it would be misdated to be somewhat younger. I might misremember but isn't the mythology something along the lines that it was grown just a short time before year 0 ? This error is going in the opposite direction then. Or theres some alternate mythology as regards templars and freemasons and such, which is too recent to be fixed by the error.

      Or the TLDR summary version of the above is ... "no, and no".

    • by EasyTarget (43516) on Monday June 04, 2012 @10:10AM (#40208355) Journal

      "Would this mean carbon dating is inaccurate for items older than 1300 years? "

      No; RC dating uses lots of correction tables to account for events like this (this is not the only such event, just the biggest one that is not explained) and for natural/cyclic variations in C14. So the effects of this will already be catered for when computing dates; it's just the 'WTF' of the event itself being discussed here.

    • by goodmanj (234846) on Monday June 04, 2012 @10:20AM (#40208481)

      No, scientists have known for a long time that the 14C creation rate isn't quite constant, and have taken this into account in order to do accurate radiocarbon dating. In fact, it was by looking at this carbon-dating calibration curve that they first noticed something unusual in 775.

      http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11123.html [nature.com]

  • by LWATCDR (28044) on Monday June 04, 2012 @08:55AM (#40207629) Homepage Journal

    Where people making observations of the Sun in 775?

  • by arthurpaliden (939626) on Monday June 04, 2012 @08:58AM (#40207663)

    The Sol system was the site of a major inter-stellar battle. Two great space armadas firing nuclear weapons at each other. Each one trying to gain a foothold in this part of the Western Spiral Arm until of course they realized there was nothing worth it here.

    Either that or a Vogon constructor fleet started making a hyper space by-pass. They got the planet between Mars and Jupiter and then the funding ran out.

    • by klik (93694)

      doesn't even need to be in this galaxy. a shot fired and missing will just keep travelling until it hits something.

    • I read a book once, it was about UFO's, ancient Chinese flying carts, and an ancient nuclear war. Maybe that is it!

  • Volcano? (Score:2, Interesting)

    by Anonymous Coward

    A Volcano could have spit out the this stuff?

    • A Volcano could have spit out the this stuff?

      Stop that! Stop that!

      You're not going to talk about Scientology while I'm here.....

  • by vlm (69642) on Monday June 04, 2012 @09:09AM (#40207781)

    Yet, as the only known events that can produce a 14C spike are supernova explosions or ... and neither event was observed at the time

    ... was observed at the time in surviving northern written records.

    Are there any detailed written astronomical observations from the southern hemisphere from that long ago?

    Also it would be pretty funny if the two guys recording solar observations in 775 both had a rainstorm the day of the largest solar flare.

    • by SirGarlon (845873) on Monday June 04, 2012 @09:49AM (#40208141)

      Are there any detailed written astronomical observations from the southern hemisphere from that long ago?

      In 775 the Maya [wikipedia.org] were almost certainly making astronomical observations. In the Eastern Hemisphere, I had to Google a bit but the Srivijaya [wikipedia.org] Empire would have had a strong interest in astronomy for navigational purposes. But neither the Maya nor the Srivijaya civilizations have near as many surviving records as do European or Chinese civilizations of the same period.

    • by goodmanj (234846)

      If it was a supernova, the Arabs and Indians were writing a lot about astronomy at around that time, and were observing from latitude 30 degrees or so. From there, they would be able to see over 90% of the sky, all but the area right at the south celestial pole. So odds are they'd have seen it. Also, the full scientific article points out that if a supernova had occurred close enough to cause the 14C spike, it would still be bright and obvious today. And while medieval Arabs might miss something, our mo

  • by Stirling Newberry (848268) on Monday June 04, 2012 @09:11AM (#40207807) Homepage Journal
    Since a near supernova enough to increase Carbon 14 levels would leave other effects, and the flares explanation is, similarly, weak.It is just as likely there was a temporary reduction in the earth's magnetic field that allowed more ambient cosmic rays to strike earth. While this amount of variation in the magnetic field is high, it isn't out of range of other events. It has the further advantage of not leaving a large number of highly visible effects, except for very strong auroras, which, given the date, might not have been recorded frequently or unequivocally enough.
    • by vlm (69642) on Monday June 04, 2012 @09:35AM (#40208017)

      It has the further advantage of not leaving a large number of highly visible effects

      What about geological magnetic field records?

      http://en.wikipedia.org/wiki/Magnetostratigraphy [wikipedia.org]

      A lot of the initial geomagnetic reversal theory was figured out by basically plotting magnetic field strips across the sea floor using pretty crude equipment. Screwing around with the field that much would seem easy to detect now?

      I had a geologist roommate once... I know just enough about geology to be really dangerous (like programmer with screwdriver)

      • 1908 - 775 = 1133.
        I've checked this several times and it always comes out the same. It's factually correct, so it must be the explanation.
      • by goodmanj (234846) on Monday June 04, 2012 @10:54AM (#40208859)

        I had a geologist roommate once... I know just enough about geology to be really dangerous (like programmer with screwdriver)

        Yeah, this probably won't work. Magnetostratigraphy typically gives you information about changes taking place over the timescale that rock formations are created -- millions of years. Those seafloor magnetic field stripes are 100,000 to a million years wide.

        That said, if you found a place with intense, continuous volcanic activity, like Hawaii or Iceland, you might be able to find a series of lava flows the right age that would preserve the magnetic field data. The problem would be precisely dating the lava flows -- you can't use 14C dating for that.

  • They bought the budget model that didn't include the extra shielding.

  • Aliens! (Score:4, Informative)

    by oneiros27 (46144) on Monday June 04, 2012 @09:16AM (#40207851) Homepage

    Lister: Your explanation for anything slightly peculiar is aliens, isn't it? You lose your keys, it's aliens. A picture falls off the wall, it's aliens. That time we used up a whole bog roll in a day, you thought that was aliens as well.
    Rimmer: Well we didn't use it all, Lister. Who did?
    Lister: Rimmer, *aliens* used our bog roll?
    Rimmer: Just cause they're aliens doesn't mean to say they don't have to visit the little boys' room. Only they probably do something weird and alien-esque, like it comes out of the top of their heads or something.

    --Red Dwarf, "Kryten"

    • Rimmer: Just cause they're aliens doesn't mean to say they don't have to visit the little boys' room. Only they probably do something weird and alien-esque, like it comes out of the top of their heads or something.

      Lister: Well, I wouldn't like to be stuck behind one in a cinema.

  • Atmospheric nuclear expolisions can also cause a spike in C14... http://en.wikipedia.org/wiki/Carbon-14 [wikipedia.org]
    The obvious answer is that earth was nuked in the year 775!!!

  • What was left of it took 775 years to get to earth.

  • Geeze, and these guys call themselves scientists.
  • by TheCarp (96830) <sjc&carpanet,net> on Monday June 04, 2012 @09:59AM (#40208243) Homepage

    775 was a year of false permissiveness when anyone could read or do anything as long as it was produced by a small cabal known as "the group", headed by "owner".

  • well (Score:5, Informative)

    by JustOK (667959) on Monday June 04, 2012 @10:10AM (#40208359) Journal

    A.D. 774. This year the Northumbrians banished their king,
    Alred, from York at Easter-tide; and chose Ethelred, the son of
    Mull, for their lord, who reigned four winters. This year also
    appeared in the heavens a red crucifix, after sunset; the
    Mercians and the men of Kent fought at Otford; and wonderful
    serpents were seen in the land of the South-Saxons.

    http://omacl.org/Anglo/part2.html [omacl.org]

  • A few hints (Score:5, Insightful)

    by aglider (2435074) on Monday June 04, 2012 @10:18AM (#40208447) Homepage

    First of all, the 14C measurements and related considerations could be simply flawed. It would not be the first time.
    Second, the fact that the primary natural source of carbon-14 on Earth is cosmic ray action upon nitrogen in the atmosphere [wikipedia.org] doesn't mean it's been a super nova for sure. That could also be due to abnormal solar activity (this is said in the article) which could easily go unobserved by civilizations that don't have the proper technology.
    Third, astronomical records at that era were relatively scarce and quite imprecise too.
    Fourth, the article talks about northern emisphere ... which would require a rather large number of samples to be studied and collected from a wide spread area (the whole northern emishere). I wonder how many (precious) samples of wood can be retrieved intact from 1200 years in the past to be literally burnt in order to measured the 14C.
    Fifth, you can also have a not-so-strong abnormal solar activity just lasting months or even quarters to produce the same amount of 14C.

    But all these could be as flawed as the original considerations ...

  • by careysub (976506) on Monday June 04, 2012 @04:25PM (#40213071)

    The original article links don't provide any useful data to assess the likelihood of either suggested potential cause (supernova or solar flare).

    Here is a nice report that does:
    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690024196_1969024196.pdf [nasa.gov] also see: http://journals.ametsoc.org/doi/abs/10.1175/1520-0469(1964)021%3C0134%3APOCBSP%3E2.0.CO%3B2 [ametsoc.org]

    What one finds is that the normal rate of C-14 production is around 2.5 C-14 atoms cm^2/sec, normally 95% of it from solar protons. The large solar flare of 1956 Feb 23, if at an opportune time of reduced shielding (the effective shielding fluctuates), would produce an annualized equivalent of 2.33, which would about double the normal production. The closest recent supernova of 1054 on the other hand is only capable of producing up to perhaps 0.2, only 8% more than normal.

    To get a 2000% increase over normal you either need a supernova 16 times closer and 250 times brighter than 1054, or you need one 20-fold super-solar flare, or 20 big normal solar flares at an opportune low shielding period. Whether or not anyone saw or recorded a supernova this close, the remnant would be glaring obvious today - it would be a naked eye object larger than the full moon. On the other hand no one even noticed a solar flare before 1857, except for the auroras seen. It suggests a rare abnormal solar flare, or a rare abnormal series of more typical solar flares is by far the most likely candidate.

    As others have noted on this thread, records do exist of strange events in the sky from that time, which might possibly refer to unusual auroras, and records from that time are terribly spotty anyway so the evidence would be expected to be thin, if present at all.

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