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Surprising supernova scars cover the Earth
- mitchbob 2y agohttps://archive.ph/2024.05.24-143644/https://www.scientificamerican.com/article/how-often-do-supernovas-strike-earth/ https://archive.ph/2024.05.24-143644/https://www.scientifica...
- pcthrowaway 2y agoDown unfortunately :'( I really hope it comes back, archive.today is doing a valuable service for humanity.
- roenxi 2y ago> Each of those iron 60–enriched layers marks a time during the past nine million years when Earth was bombarded by a nearby supernova. As the article notes, this sounds like it is a remarkably common event. Dinosaurs only died out around 100 mya.
- gumby 2y ago> Dinosaurs only died out around 100 mya. They did? I need only step into my back yard to see birds and lizards. > remarkably common event Probably not normally distributed but depends on the age of a given galaxy. But indeed, it does look like they are not super uncommon in our neighborhood.
- booleandilemma 2y agoI think parent meant the kind of dinosaur that can eat you.
- forgetfulness 2y agoThe correct term is "non-avian dinosaur" for the ones that died en masse, but making that point in the first place is already pretty pedantic, doing it with snark is just being annoying for the sake of being annoying.
- perihelions 2y agoWe're far off the topic of the thread which is iron-60 supernova paleoarchaeology but I can't help myself from pulling things even further off-course. Did you know there were flying dinosaurs in the medieval era that hunted humans from the skies? - "'[Haast's] eagle had the possibility to hunt people,' Joanne says. 'It's hard to imagine a bird in that role but if it could successfully hunt a 250kg moa, then 80kg humans were possibly on the menu. There is oral tradition which suggests it was the case.'" https://www.nhm.ac.uk/discover/news/2021/december/worlds-largest-eagle-hunted-unlike-any-other-bird-of-prey.html https://www.nhm.ac.uk/discover/news/2021/december/worlds-lar... https://en.wikipedia.org/wiki/Haast%27s_eagle https://en.wikipedia.org/wiki/Haast%27s_eagle
- thaumasiotes 2y ago> It's hard to imagine a bird in that role What? People have been imagining birds in that role for as long as there have been people. Has Joanne never heard of rocs?
- gus_massa 2y ago>> It's hard to imagine a bird in that role Do they have to fly? Have you ever meet Ostrich or Rheas? (Protip: Keep your fingers, food and everything shinny hidden. They will not eat your fingers, but I can't guaranty that.) A giant Ostrich would make me very afraid, but the giant versions are extint. PS: Goose are smaller but very mean. I'd be even more afraid of a giant goose if they were real.
- tsimionescu 2y agoWhile birds are technically a kind of dinosaur, lizards are not.
- BurningFrog 2y agoNote that there are only 2 such layers. "60" refers to the Iron-60 isotope.
- AnimalMuppet 2y ago> Dinosaurs only died out around 100 mya. Isn't 66 mya the generally accepted value?
- busterarm 2y agoAt the time scales we're considering that's not even a rounding _error_.
- HunterWare 2y ago40% is a rounding error? I hope not ;) (edit, fine 34%... but I'll say THAT might be a rounding error grin)
- dmd 2y agoIt's not 40%, though; the relevant 100% is not 100 million years, it's "several billion years".
- busterarm 2y agoI said specifically it's not a rounding error. You would, at minimum, round to the nearest hundred million years, which was done.
- AnimalMuppet 2y agoNo. First, if the best known number is 66 mya, why throw away almost all the precision and call it 100 mya? Second, the number it was being compared to in roenxi's comment was 9 million years, not 4 billion years. So, yes, it is in fact a rounding error. ;-)
- roenxi 2y agoAs numbers get bigger the amount of rounding gets more acceptable. 100 to 101 is as 1e100 to 1e101, despite te latter technically being off by 90%. I think 100mya is perfectly fine. It doesn't undermine the point and this isn't trivia I plan to remember more accurately than that.
- Aardwolf 2y agoAccording to this there would be 250,000 stars within a 250 light year radius from Earth: https://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/Back/250lys.html https://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/LocalGroup/B... So if all of those will explode eventually, that's a lot of supernovas (if the Earth is still around for all of those...)
- nappy-doo 2y agoNot all of those explode eventually, rather it's a small amount. Only the most massive stars explode into a supernova. The majority of stars are smaller, and will have different lifetimes. For example, the sun, an unusually bright star (brighter than about 95% of stars) will eventually turn into a red giant, slough off material then collapse to a white dwarf. It's estimated that the majority of stars are brown dwarf (very small, some not too-too much larger than Jupiter), and less than 1% of stars are massive enough to go supernova. The problem is that only the big stars go super nova, and the big stars also have the short lifetimes because they're burning fuel so quickly.
- pfdietz 2y agoWhite dwarfs can also explode, if they are in a binary system. It's a different kind of explosion (more akin to a thermonuclear bomb) but it also produces iron.
- v3ss0n 2y agoDoes it trigger an ELE?
- jdiff 2y agoNo, the article says the only noticeable effect was a particularly bright star. The same amount of material received from the supernova is absorbed by earth each day. It was an ordinary Tuesday besides the lightshow.
- BurningFrog 2y agoChatGPT says: In astronomy, ELE stands for Extinction-Level Event
- perihelions 2y agoAn exceptionally large cosmic radiation source could cause mass extinctions—it's a postulated explanation for several of the geologic ones. That's not due to the radiation itself. The mass column of the atmosphere—equivalent of a 10-meter thick water layer—is plenty adequate radiation shielding. Rather it's secondary effects of the interaction of radiation with the high atmosphere, such as the destruction of ozone. https://arstechnica.com/science/2020/08/researchers-propose-a-supernova-triggered-the-late-devonian-mass-extinction/ https://arstechnica.com/science/2020/08/researchers-propose-...
- chasil 2y ago"As matter expands away from the blast site, it thins out, so by the time the ejecta from a nearby supernova reaches Earth, perhaps a few hundred metric tons might rain upon our planet over a length of time. That might sound like a lot, but about that same amount of meteoric material slams into our atmosphere every day. So supernovas aren’t appreciably adding to Earth’s weight, nor are they a big danger to us in this way."
- badcppdev 2y agoObligatory xkcd reference: https://what-if.xkcd.com/73/ https://what-if.xkcd.com/73/ > Which of the following would be brighter, in terms of the amount > of energy delivered to your retina: > * A supernova, seen from as far away as the Sun is from the Earth, or > * The detonation of a hydrogen bomb pressed against your eyeball? > > ... the supernova is brighter ... by nine orders of magnitude.
- cduzz 2y agoAny time you're killed by neutrino radiation poisoning you're likely done in by a bunch of other things at the same time...
- jajko 2y agoto the point that probably all atoms once within your body are spread rather evenly far from each other, and not coming back
- adrianN 2y agoLethal doses of neutrinos are a plot point in Diaspora by Greg Egan.
- luyu_wu 2y agoAlso in Supernova Era if I remember correctly!
- duncan-donuts 2y ago[flagged]
- hammock 2y agoSummary - Scientists have found evidence of two separate supernova events in the last 7.5 million years that showered the Earth with radioactive debris like iron-60. These events were traced back to the Scorpius-Centaurus association of young, massive stars about 300-400 light-years away. While the amount of supernova material that reaches Earth is tiny compared to the total ejecta, it indicates that our planet has been bombarded by radioactive ashes from exploding stars thousands of times over its history. The most recent known nearby supernova event may have been visible in the sky to early human ancestors like Australopithecus afarensis, appearing as a bright star or "guest star" in the sky
- bell-cot 2y agoWelcome to the "new & improved" Scientific American. I was a subscriber from ~1972 to ~2000, and kept my old issues. Folks have told me that even in '76, SciAm had been heading down for a long time.
- deleted 2y ago[deleted]
- adolph 2y agoThat in turn is important because we only know of one natural place where this isotope can be forged: in the nuclear fires of a supernova. Some scientists will do anything but consider the Silurian hypothesis. https://en.wikipedia.org/wiki/Silurian_hypothesis https://en.wikipedia.org/wiki/Silurian_hypothesis
- Iolaum 2y agoWhile that's an interesting argument I don't this applies to the Fe-60 isotope. I don't think we know of an energy production process (fission or fusion) that would result in Fe-60 as a byproduct which would cater to the Silurian hypothesis. Especially in the quantities and locations discovered. Hence I think their assumptions - of looking for natural places where the isotope is forged - in this case are valid.
- pfdietz 2y agoA DT fusion reactor with iron in its structure would produce a small amount of Fe-60, by double neutron capture on Fe-58. The amount would be limited because the half life of Fe-59 is 44.5 days.
- idiotsecant 2y agoBecause it seems pretty ridiculous on it's face. We might not have monuments of an ancient civilization, but we'd expect to see records of an equivalent anthropocene in the geologic record, similar to what we're making now, more or less. Increased bio-carbon deposits, increased sedimentation from agriculture, etc. We might as well wonder why scientists didn't consider whether the deposits of iron 60 were put there by mischievous leprechauns. 'scientists' need not consider every crackpot theory because someone on the Internet thinks they should.
- fooker 2y agoIt’s not so ridiculous once you learn that most of the earths crust gets recycled within 500 million years, and more than half gets recycled within a mere 100 million years. That’s why we don’t find fossils everywhere. And if humanity goes extinct today, it would be fairly tricky to find evidence of us in a billion years. It’s of course a non falsifiable hypothesis, so there’s not much we can do. But plenty of people believe in another non falsifiable hypothesis——invisible man in the sky.
- throwaway5959 2y agoIs there a way to filter out articles that are pay-walled? I know this is unrelated to the article but I’m curious as I’m tired of clicking on links and being unable to read them.
- deleted 2y ago[deleted]
- Traubenfuchs 2y agohttps://archive.is/ztYsz https://archive.is/ztYsz
- zamadatix 2y agoExpanding on the sibling's link you can prepend "archive.is/" to the url and it'll either have a snapshot already or you can click the link to create one. Typically a popular article that paywalls itself will have one of these links in the comments already as well. I think it's one of the more annoying policies on the site (won't avoid paywalled posts but also hides that it expects everyone to do that workaround to participate anyways) but it's pretty easy to deal with once you know the above dance.
- bilsbie 2y agoWe’ve been destroying our planet for a long time.
- cletus 2y agoHere's a partial list of civilization ending events: - Nearby supernovae - Gamma ray bursts (eg from a neutron star that happens to be pointing directly at us and is sufficiently close) - Large icy or rocky bodies hitting the planet - Coronal mass ejections - In about 1.6 billion years the increasing Solar output will make Earth uninhabitable - In about 4 billion years the dying Sun will expand and essentially swallow the Earth, which will be long dead anyway And here's a list of terretstial civilization killers: - Supervolcanoes - Climate change - Global war - Disease - Ice ages There are also others that we don't know how disruptive they will be other than probably super disruptive like the magnetic poles flipping (yes, this has happened at least 30 times). My point here is that living on Earth is living on borrowed time. To survive in the really long term, we are going to have do something pretty drastic. Whatever we do (eg interstellar travel, moving the EArth--yes, this is possible) will require such massive energy expenditure that IMHO the only path forward will be to build a Dyson Swarm. I'm also not yet convinced we can think of the time scales required to avoid our own destruction but at least, for a brief period of time, we will have created an awful lot of shareholder value. Over sufficiently long time periods, all of these turn from an "if" into a "when".
- cryptonector 2y agoAdd "running out of CO2" and "the atmosphere thins too much" to the list. I don't know when those could happen, but they've been happening slowly for billions of years, and they will finish happening eventually, most likely well before the Sun's output gets too high.
- cletus 2y agoAtmospheric loss is an interesting and not-entirely-understood subject [1]. But here's one aspect we do know that puts the scale in context. Any gas has a Boltzmann distribution of kinetic energies. You can calculate that a certain portion of that will have a kinetic energy high enough to escape gravity. This is called the Jeans escape energy [2]. For Earth this amounts to losing 60-100,000 tons of atmosphere every year, which is actually a complete non-issue. I mention this because the idea of terraforming Mars is a popular sci-fi trope but really makes absolutely zero sense. Mars has lower gravity (and no magnetic field, although part this is fixable) so the atmospheric loss would be significantly higher if we wanted to produce 1 atmosphere of pressure at the surface. So however we produced that atmosphere would have to be able to sustain a loss of 100,000+ tons of atmosphere every year as a rounding error. That's the scale of just one of the many problems in terraforming Mars. You also have to produce (or ship in) that atmosphere without boiling the planet. The scale combined with thermodynamics makes this a nontrivial problem. And where is all this energy coming from? We return back to the Dyson Swarm. [1]: https://sseh.uchicago.edu/doc/Catling2009.pdf https://sseh.uchicago.edu/doc/Catling2009.pdf [2]: https://en.wikipedia.org/wiki/Atmospheric_escape#Jeans_escape https://en.wikipedia.org/wiki/Atmospheric_escape#Jeans_escap...