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Effect of a giant meteorite impact on Paleoarchean environment and life
- EGreg 2y ago[flagged]
- dan353hehe 2y ago> Drabon and her colleagues went in search of evidence of ancient major impacts in a remote area south of Kruger National Park in South Africa. There they sought out rocky outcrops containing a layer of spherules – molten droplets formed following a major meteorite impact that rained down over huge swathes of the planet. There are eight such spherule bands in this area, each preserving an ancient impact event. > While the impact crater itself is long gone, analysis of rocks from 3.26 billion years ago tells a tale of planetary devastation. The layer of spherules from this huge impact was 15 to 20cm thick in places, compared with less than a centimetre for the famed dinosaur-killing meteorite, says Drabon.
- EGreg 2y ago[flagged]
- mmooss 2y ago> it's just a theory that tries to fit this data What do you feel is missing? You might find that if you read the paper, it goes through the evidence, prior evidence, and their hypothesis.
- andrewflnr 2y ago> Yeah, but it's just a theory that tries to fit this data. Doesn't mean it is correct. Yes. What else do you expect from science, or really from any human attempt to find truth? Are you just upset they don't include the caveat "subject to potential future evidence or better theories" on literally every single piece of science journalism? Are you upset that people do their best to make sense of weird situations and then tell people about their work, even if it's not absolute truth? What do you want to happen here?
- drdaeman 2y agoI hope that your reaction is because the headline is way more sensational (to the extent of probably being incorrect) than the actual paper's abstract (https://www.pnas.org/doi/10.1073/pnas.2408721121 https://www.pnas.org/doi/10.1073/pnas.2408721121) Here's what the actual paper says: > [...] Thus, the S2 impact likely had regional, if not global, positive and negative effects on life. The tsunami, atmospheric heating, and darkness would likely have decimated phototrophic microbes in the shallow water column. However, the biosphere likely recovered rapidly, and, in the medium term, the increase in nutrients and iron likely facilitated microbial blooms, especially of iron-cycling microbes. Which sounds and - if I understand it correctly - means something kinda different than how "reset early life" is ordinarily understood, huh.
- EGreg 2y ago[flagged]
- dang 2y agoPlease don't take the bait. It's fine to let us know when a headline is sensational/distorted so we can change it. It's not fine to take to the comments about it, because that is likely to produce a shallow and less interesting discussion, which is what happened here. Edit: I've changed the title to that of the paper.
- _moof 2y agoHave you got a better theory that fits all available data and has predictive power?
- tracerbulletx 2y agoPublications are institutionally incapable of publishing an article (and readers incapable of appreciating) that says, A Paper Investigates How Early Archean Impacts Might Have Possibly Affected The Development of Nascent Life
- animex 2y ago[flagged]
- tengbretson 2y agoYep. Good ol' observing, questioning, hypothesizing, experimenting, analyzing and concluding.
- mmooss 2y agoThe purpose of scientific papers is to explain that, starting with observations.
- iambateman 2y agoThe downvotes are misplaced. This is a good question. The value of HN is when people-who-know help curious folks understand the validity of a story. Surely someone here is more capable of assessing this story and I agree that skepticism is in order at first.
- phalangion 2y agoExcept the article explains in fairly easy to understand terms how the study came to this theory, and the original paper is linked from that article. The question here gives the impression that the asker read only the headline.
- _moof 2y agoThe downvotes are because people are reading the question as rhetorical rather than being asked out of genuine curiosity. It's only a good question if the person asking it is doing so with an open mind. (That and the article answers the question.)
- bulatb 2y agoSkepticism should begin with the skeptic's own motives. A skeptic's second question (after "Really?" or "Why?") should be, "Why am I asking?" Do they want to test the claim to learn something, or to dismiss it, just to dismiss it? If they're asking questions which are literally answered as part of the claim, they need to start over, and start with themselves.
- iambateman 2y agoThe article claims that 363 billion tons of phosphorous were dropped on earth 3.26 billion years ago during a decade of darkness. I’m completely incapable of making sense of that claim because it’s so far outside of my expertise. But my fundamental problem is that I don’t trust the source’s incentives to deliver reliable information and I want someone independent to help me understand if this is a how strong or weak this science is. And my starting point for that is “it’s very hard to know anything specific about the deep past. And I’m tired of scientific retractions.”
- kevinkeller 2y agoI love this type of articles where we can reconstruct what happened so long ago just based on careful observations. Some other instances I've come across: * The K-Pg extinction event that wiped off dinosaurs had the impact it did because the asteroid happened to impact a shallow water region. This kicked up a lot of sulfur (in gypsum) that further affected global climate: https://en.wikipedia.org/wiki/Chicxulub_crater#Effects https://en.wikipedia.org/wiki/Chicxulub_crater#Effects * Earth likely had rings ~466M years ago. We deduced this by looking at impact craters from that time period, and seeing that they all lie near the equator (accounting for continental drift): https://www.sciencedirect.com/science/article/pii/S0012821X24004230 https://www.sciencedirect.com/science/article/pii/S0012821X2... * Earth's rotation period was probably frozen at 21h, ~600M years ago, likely due to interaction between lunar and solar tides. This resonance could have been broken by ice ages (!!!). Amazing to think that global climate affects earth's rotation: https://en.wikipedia.org/wiki/Earth%27s_rotation#Resonant_stabilization https://en.wikipedia.org/wiki/Earth%27s_rotation#Resonant_st...
- thangalin 2y ago> reconstruct what happened so long ago just based on careful observations. Me too! My book is filled with them. Like how minerals in lava, affected by Earth's magnetic field, lock into place while cooling, which provides us with yet another cross-check for radiometric dating. See page 23: https://impacts.to/downloads/lowres/impacts.pdf https://impacts.to/downloads/lowres/impacts.pdf
- chiefalchemist 2y agoNot to nitpick but the dinosaurs were on already on the way out, the asteroid merely finished them off early. https://www.theatlantic.com/magazine/archive/2018/09/dinosaur-extinction-debate/565769/ https://www.theatlantic.com/magazine/archive/2018/09/dinosau...
- Arech 2y agoTo the best of my knowledge not everyone agrees to that hypothesis. One of the strongest arguments against it is that paleontological evidence is always incomplete. Holes in it that are treated in favor of the hypothesis are actually smaller or comparable to holes that appear just due to incompleteness.
- jeffbee 2y agoThe paper also mentions that, at the time, "dinosaur killer"-sized objects hit the Earth every 15 million years on average, which must have been sort of disruptive.
- kevinkeller 2y agoLikely due to this: https://en.wikipedia.org/wiki/Late_Heavy_Bombardment https://en.wikipedia.org/wiki/Late_Heavy_Bombardment
- jeffbee 2y agoWhat these authors claimed recently was that prior LHB estimates were low by a large factor. https://www.nature.com/articles/s41561-021-00835-9 https://www.nature.com/articles/s41561-021-00835-9
- kevinkeller 2y agoThanks for the paper link!
- 1970-01-01 2y agoVote for Giant Meteor 2028! https://votegiantmeteor.com/ https://votegiantmeteor.com/
- hehehheh 2y agoWhen is the next one coming? Or what is the probability distributuon like?
- patrickthebold 2y agoIt's a poisson distribution.
- dataflow 2y agoHave the data actually been fit a Poisson distribution? Or is this is just a guess assuming constant rate and independence?
- glial 2y agoNo natural phenomena ever exactly fits any probability distribution.
- dataflow 2y agoRight but I'm saying do we have data showing it's even close? (Genuinely asking, I have no idea.)
- Q_is_4_Quantum 2y agoexcept the emission spectra from atoms :)
- nverno 2y agoI imagine it is more of an exponential decay mixed with poisson since strikes were far more common back in the day. Also, I'd guess an exponential decay in the expected size of impactors over time as they've been smashing themselves into pieces.
- Arech 2y agoLikely it isn't, because the Solar system today and 3Bln years ago are two very different systems.
- dang 2y agoThe paper is at https://www.pnas.org/doi/10.1073/pnas.2408721121 https://www.pnas.org/doi/10.1073/pnas.2408721121. We've adopted its title above.
- Timwi 2y agoThe article perpetuates the widespread misconception that dinosaurs are extinct. In reality, (some) dinosaurs survived and evolved into modern birds. Everything from penguins to ostriches, hummingbirds to albatrosses and woodpeckers to eagles is a dinosaur. Science communication should do better and clear up this misunderstanding. It would be so much cooler to say that the asteroid killed the pterosaurs. Not only is it factually correct, it also opens doors to more curiosity. Why do they say pterosaurs instead of dinosaurs? Turns out they are separate clades. The pterosaurs, plesiosaurs and mosasaurs are all extinct as best as we can tell. The dinosaurs are not.
- bregma 2y agoDinosaurs are delicious. They taste like chicken.
- pier25 2y agoProof we live in a simulation. Everything tastes like chicken!
- jvanderbot 2y agoThis is fascinating. Although I'm having trouble mapping your comment onto this: https://opengeology.org/historicalgeology/case-studies/dinosaur-classification/ https://opengeology.org/historicalgeology/case-studies/dinos... What is the complete set and which are extinct?
- addaon 2y ago> What is the complete set and which are extinct? That's as good a complete tree as you're likely to get, down to the class level. Some species in the class Aves survived, and progenitor species with Aves are still around today. There's no significant evidence of species in other classes of the clade Dinosauria surviving much past the impact boundary. You can push this up one level to the clade Avemetatarsalia (including Pterosaurs along with Dinosaurs) and the statement above would still be true; but pushing it further to Archosauria would not be valid, because crocodilians survived (and survive) as well.