6 ms·
Possible exposure of Earth to dense interstellar medium 2-3M years ago
- profsummergig 2y agoAnyone here read "Neck of the Giraffe"? He hypothesizes that cosmic ray bursts are responsible for mutational leaps in evolution. This seems similar.
- dilippkumar 2y agoI thought Ford Prefect was responsible for this one.
- buildbot 2y agoThat entire sequence is so absurd. Leaves are money!
- FooBarBizBazz 2y agoThe timing does seem to roughly match first known tool use in Homo habilis, if my Googling serves me well.
- jauntywundrkind 2y agoThe geologic time record shows a pretty noticeable drop in this time frame, before the glacial period started & temperatures started swinging up & down. https://en.wikipedia.org/wiki/Geologic_temperature_record#Overall_view https://en.wikipedia.org/wiki/Geologic_temperature_record#Ov...
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- animaomnium 2y agoVery interesting paper! Proposes (with lower bound of 1.3% chance) that the solar system may have passed through a local interstellar cloud, which would have caused the heliosphere to shrink to smaller than the orbit of the earth (0.22 au) some 2-3 mya. This may have affected the Earth's atmosphere and climate. Scroll down for some cool illustrations of a simulation showing how the heliosphere would have been tiny with an elongated tail in a denser interstellar medium. There's also a map showing the interstellar cloud relative to the trajectory of the solar system.
- dylan604 2y agoThat's one of those fun astronomy topics that is mind boggling to think of the forces involved to diminish the effect of Sol's solar radiation to that level.
- delichon 2y ago> This may have affected the Earth's atmosphere and climate. Adding uncertainty to climate forecasting models. Can we detect or predict changes to the interstellar medium in our path through space and improve forecasts with that? Maybe we could at least put an upper bound on the magnitude of the effect.
- gerad 2y agoI learned this in the Cal Academy of Sciences the other day! Apparently we’re about halfway through a region of less interstellar activity. https://en.m.wikipedia.org/wiki/Local_Bubble https://en.m.wikipedia.org/wiki/Local_Bubble
- westurner 2y agoAre there fossil records that correspond to higher levels of dense interstellar medium radiation 2-3M years ago? Punctuated equilibrium: https://en.wikipedia.org/wiki/Punctuated_equilibrium https://en.wikipedia.org/wiki/Punctuated_equilibrium
- gliptic 2y agoPunctuated equilibrium is not about higher mutation rates or even faster evolution, but about long periods of _stasis_ interrupted by "normal rate" evolution due to an upset in the equilibrium such as a sudden geographic isolation of two populations.
- westurner 2y agoWas there a higher rate of cladogenesis 2-3M years ago? Higher levels of radiation do correlate to higher rates of genetic mutation; presumably because radiation so affects transcription. Does the punctuated equilibrium theory model radiation level in estimating rate of evolution? Rate of evolution: https://en.wikipedia.org/wiki/Rate_of_evolution https://en.wikipedia.org/wiki/Rate_of_evolution
- jcims 2y agoEvery square meter of a space ship passing through this at the speed of light would interact with ~3e13 hydrogen atoms per second. I don't know if I did this correctly but that's only ~27kJ per second of mass energy. I thought it would be a lot more.
- dylan604 2y ago> I thought it would be a lot more. Yet another example of just how big space is, and how empty atoms are
- jcims 2y agoEvery time i even remotely have the illusion of understanding it gets upended. I think that’s why i like it so much
- EnigmaFlare 2y agoIn the space-ship's frame, it would be a lot more.
- SJC_Hacker 2y agoIf it was the speed of light, it would be infinite mass-energy. Which is why you normally talk of "x% of the speed of light", e.g. 99% of the speed of light.
- bloopernova 2y agoAre we able to determine if other star systems have experienced the same type of encounter? (Not statistically, I mean detection or instrument based) I'm assuming it's either difficult or impossible to measure another star's heliopause. It would be fascinating to see the effects of a cold cloud interaction in "real" time!
- s1artibartfast 2y ago>I'm assuming it's either difficult or impossible to measure another star's heliopause. It would be fascinating to see the effects of a cold cloud interaction in "real" time! I'm pretty sure we observe it routinely. There are tons of beautiful pictures of stars blowing away Nursery nebula. This is the heliopause of those Stars interacting with dense interstellar medium
- jcims 2y agoPresumably it has happened before in the history of the earth but it would be interesting to know what effects it had on life on earth and, by extension, the arrival and development of modern humans.
- NooneAtAll3 2y agoare there no tree fossils from that era that can show one part of the year being different from the rest? I remember reading that dinosaur meteorite was discovered to have fallen in spring by those marks surely regular pattern of getting in-out of heliosphere be noticeable?
- s1artibartfast 2y ago>surely regular pattern of getting in-out of heliosphere be noticeable? Why do you say that? What would you look for?
- itishappy 2y agoInterstellar isotopes! > By studying geological radioisotopes on Earth, we can learn about the past of the heliosphere. Fe60 is predominantly produced in supernova explosions and becomes trapped in interstellar dust grains. Fe60 has a half-life of 2.6 Myr, and Pu244 has a half-life of 80.7 Myr. Fe60 is not naturally produced on Earth, and so its presence is an indicator of supernova explosions within the last few (~10) million years.
- vlz 2y agoInteresting question! From the Dendrochronology article on Wikipedia it seems we can at most go 14k years into the past with tree rings: > Bard et al write in 2023: "The oldest tree-ring series are known as floating since, while their constituent rings can be counted to create a relative internal chronology, they cannot be dendro-matched with the main Holocene absolute chronology. However, 14C analyses performed at high resolution on overlapped absolute and floating tree-rings series enable one to link them almost absolutely and hence to extend the calibration on annual tree rings until ≈13 900 cal yr BP." https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#Continuous_sequence https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#C... Interestingly it seems that tree ring chronologies can be mapped to increases in cosmic radiation named "Miyake events". https://en.wikipedia.org/wiki/Miyake_event https://en.wikipedia.org/wiki/Miyake_event
- barfbagginus 2y agoWhy does this make me feel a little dirty and exposed? Like, who knows what kinda alien DNA strands or spores are carried by the ISM?! I wonder if it would be possible to track biodiversity increases caused by the transit? Assuming there is biological material in the ISM, perhaps some of it made it into our biosphere! Very fun!
- dylan604 2y agoMaybe it was a large cloud of mushroom spores: https://en.wikipedia.org/wiki/Panspermia https://en.wikipedia.org/wiki/Panspermia
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- barfbagginus 2y agoThis is an amazing idea! In my response to imiric, I detail an ICM Panspermia version of the Stoned Ape Theory, and hypothesize that we could use genomic dating techniques to experimentally falsify the theory (which is probably false because we probably had magic mushrooms for many millions of years). That makes it a fun theory to work with!
- shiroiushi 2y agoRemember, modern humans appeared around 1.5-2M years ago, so this event, geologically speaking, happened shortly before the arrival of modern humans. Perhaps this event had something to do with us evolving.
- bloopernova 2y agoDo you mean Homo Erectus or Homo Sapiens? Sapiens arrived around 300k years ago, according to Wikipedia. Erectus did indeed arrive around 2M years ago. https://en.wikipedia.org/wiki/Human https://en.wikipedia.org/wiki/Human https://en.wikipedia.org/wiki/Homo_erectus https://en.wikipedia.org/wiki/Homo_erectus
- mlhpdx 2y agoI wonder what effect this would have had on the sun itself — not like blowing in a fire, apparently.
- kadoban 2y agoVanishingly close to no effect at all. It's hard to have an effect on something you could throw planets at without harm.
- itishappy 2y agoNone! The Sun has a forcefield called the heliosphere to protect it, and this protects the planets as well. This paper is arguing that the interstellar medium may have been dense enough to shrink the heliosphere to within the orbit of some planets, but it'd take a helluva lot more to shrink it down to the Sun's surface. https://en.wikipedia.org/wiki/Heliosphere https://en.wikipedia.org/wiki/Heliosphere
- mlhpdx 2y agoI understand, but given the dramatic change I'd expect some things to "bend" a little. Perhaps literally, like solar flares? Does "holding them closer" increase/decrease surface temperature?
- itishappy 2y agoFair enough, I'm sure "none" is a slight exaggeration. Two effects I could see (but have no source for) are: 1. A slightly increased return radiation due to the increased proximity of the heliopause and the the increased collision rate with the denser interstellar medium. The radiation from this should reach the surface of the Sun and slightly increase surface temps, but this effect would be dwarfed by the amount of radiation already coming from the Sun itself. 2. A tighter coupling of the Sun's magnetism to the stellar wind and interstellar magnetic field. This would slow down the Sun's rotation slightly, and it if increased differential rotation it could cause an increase in solar flare activity.
- semireg 2y agoIt’s not every day you read something that completely boggles your mind. Our solar system passes through interstellar clouds and it can affect our planet. Wow.
- showlife 2y agoReminds me of the plot of "Exit Earth" by Martin Caidin where humanity has to evacuate the planet in an ark to survive passage through an interstellar dust cloud. Martin Caidin is known more for "Cyborg", the book that was used as the basis for the TV show "The Six Million Dollar Man".
- noobermin 2y agoWait are they arguing this is what caused the last ice age, essentially????
- pvaldes 2y agoseems a decent explanation
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- anacrolix 2y agoThat's when the aliens in the cloud modified the genome of primates and set us on the course that is today.
- boredemployee 2y agocurse*
- Grimblewald 2y agothe ultimate prank. "hey Xe-lurp, lets make 'em ponder"
- noobermin 2y agoJust a comment, I sent this to my advisor who was an astrophysicist a few years back (he and I are in plasma physics today) and here's something he pointed out, "[...]Abraham Loeb is about as controversial of a figure in astronomy as you can find. He is also the head of a UFO monitoring project and he still insists that the rod like object that telescopes saw pass through the solar system about a decade ago had an extraterrestrial origin." Googled his name (he's one of the co-authors of this article) and found this on his wiki page: "In 2018, he suggested that alien space craft may be in the Solar System, using ʻOumuamua as an example.[7] In 2023, he claimed to have recovered material from an interstellar meteor that could be evidence of an alien starship,[8] which some experts criticized as hasty and sensational,[9][10] and for which other experts found more Earth-related explanations instead, demonstrating that the seismic signal attributed by Loeb to the alleged interstellar space craft was actually caused by ordinary truck traffic.[11]" Take from this what you will. The section on the Galileo project talks more about the controversy surrounding him. https://en.wikipedia.org/wiki/Avi_Loeb https://en.wikipedia.org/wiki/Avi_Loeb
- snowwrestler 2y agoKeep reading down that Wikipedia page and you’ll see that he is also a serious and well-respected scientist.
- DiggyJohnson 2y agoHe's controversial but not crazy. Lots of interesting people are controversial. I think you understand that, but I'm sharing this comment so that others aren't immediately turned off at the notion.
- thegrim33 2y agoCan you believe that Galileo guy? What a crank. What a controversial figure. He actually insists that the Earth goes around the Sun. That's not science, that's just a madman, all our scientists know that the truth is the other way around. Don't read this new paper he wrote guys, look at the controversy surrounding him. Take from this what you will.
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- Grimblewald 2y agoSomething interesting to note, the rough timing of this occurring, if it did, coincides with the appearance of homo erectus.