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Alien star system buzzed the Sun
- 1971genocide 12y agoWeren't humans alive back 70,000 years ? I wonder if one of our ancestor then gazed at the sky and saw something or not. Guess we will never know :(
- antognini 12y agoThe authors actually discuss this possibility in their paper. (Section 4 of [1].) The star is very faint (an M dwarf), so even at its nearest approach it would have been far too faint to be seen with the naked eye. However, M dwarfs do show occasional flares, so it is possible that it would have brightened to be visible to the naked eye for a few minutes to hours during a flare event. [1]: http://arxiv.org/abs/1502.04655 http://arxiv.org/abs/1502.04655
- scrumper 12y agoPossibly a fairly dim point of light, moving slowly like a planet? It was a red dwarf star (with a brown dwarf companion) so not that bright in the first place, and very, very, very far away - that perspective diagram has a log scale. The sun seen from the outer planets isn't much more than a particularly bright star, and it's much bigger and hotter than Scholz's star.
- lkbm 12y agoYes, I believe modern humans came about around 200 000 years ago, and around 70 000 years ago were heading out of Africa.
- ddeck 12y agoNot sure why you're being down voted without comment since you directly answered the parents question with broadly accurate information: Anatomically modern humans first appear in the fossil record in Africa about 195,000 years ago (see Omo remains), and studies of molecular biology give evidence that the approximate time of divergence from the common ancestor of all modern human populations was 200,000 years [1] Migration out of Africa is estimated at around 125000 years ago for modern humans. [2] [1] http://en.m.wikipedia.org/wiki/Homo_sapiens http://en.m.wikipedia.org/wiki/Homo_sapiens [2] http://en.m.wikipedia.org/wiki/Early_human_migrations http://en.m.wikipedia.org/wiki/Early_human_migrations
- lfnoise 12y ago20 light years per 70000 years in miles per hour = 191604.751 miles per hour, according to google
- joshvm 12y agoIt's travelling at around 80km/s radially according to the paper so that sounds about right. Almost all the velocity is radial, only 3km/s is observed tangential to us. In perspective, it's only around 4-5 times faster than Voyager 1 or New Horizons.
- eyko 12y agoIt's also _speeding_ away (no info on how many km/s per year faster it is?). It could've been much slower 70.000 years ago.
- mangeletti 12y agoSince it is moving away from a large body of mass, namely, the day star, it's likely that it has been decelerating over the past 70k years, meaning it would have been moving more quickly when it passed by.
- andyjohnson0 12y agoThe article links to a paywalled source for the paper "The Closest Known Flyby of a Star to the Solar System" by Mamajek et al. Full text is freely available on arXiv at [1]. [1] http://arxiv.org/abs/1502.04655 http://arxiv.org/abs/1502.04655
- jessriedel 12y agoFor reference, 0.8 light years is about 50,000 AU. (AU = the distance from the Earth to the Sun.) Pluto is about 49 AU away.
- JoeAltmaier 12y agoRight, the Oort cloud is frickin huge - goes halfway to the next star (well, what we used to think of as the next star)
- mrec 12y agoAnd presumably the next star's own Oort cloud goes halfway to us, meeting ours in the middle? I remember some people a while back playing with the idea that the practical way for humanity to colonize the stars was by very gradually "rock-hopping through the Oort cloud", as opposed to "One Giant Leap" approaches like generation ships or crossing our fingers and desperately hoping for hyperdrive.
- dragonwriter 12y ago> And presumably the next star's own Oort cloud goes halfway to us I don't know that we have enough information about how the size of Oort-like clouds would relate to other observable cahracteristics of stars to have a reasonable basis for any conclusion about the size of "Oort clouds" of other nearby star systems.
- mrec 12y agoYou're right, "presumably" was much too strong a word. "Potentially", maybe.
- JoeAltmaier 12y agoWe assume gravity, the speed of light etc are the same everywhere. What reason have we to suppose our own stellar neighborhood is the only one to have an Oort cloud? If we assume physics is the same everywhere, then this cloud would extend throughout the galaxy.
- hasenj 12y agoI'm starting to wonder if a somewhat similar event could have occurred ~66 million years ago and triggered a series of events leading to the extinction of dinosaurs.
- Thrymr 12y agoThat is basically the Nemesis hypothesis: http://en.wikipedia.org/wiki/Nemesis_%28hypothetical_star%29 http://en.wikipedia.org/wiki/Nemesis_%28hypothetical_star%29
- Sanddancer 12y agoThat's the basis of the Nemesis hypothesis [1]; that supposedly there's a star that roughly orbits the sun and causes havoc every few miillion years. However, it's been pretty much debunked at this point [1]http://en.wikipedia.org/wiki/Nemesis_%28hypothetical_star%29 http://en.wikipedia.org/wiki/Nemesis_%28hypothetical_star%29
- hasenj 12y agoWell it doesn't have to be orbiting the sun and causing this periodically. It could've been a one time event.
- tomphoolery 12y agoWas gonna come in here to ask...will this explain Nemesis as not a recurring event but rather a one-time event caused by that trailing brown dwarf (or the star itself) flinging comets all over the place. It would also explain a lot of other crater-rich surfaces dating back to that time...
- legohead 12y agoDealing with asteroids feels plausible.. but how to deal with a star? scary stuff
- NoMoreNicksLeft 12y agoHow visible would this have been in the night sky?
- jccooper 12y agoAccording to the paper, not at all, barring some nicely-pointed flare events. It's a very dim star.
- mangeletti 12y agoAs a starting point, the sun's absolute brightness is much higher than this star's, and this star supposedly came within .8 light years of us. That's 50,591 further than Earth is from the sun, which means it would be no brighter than most of the stars you see in the sky... unfortunate, huh :(
- mangeletti 12y agoI meant "50,591 times further".
- jarin 12y agoNot only is this super amazing, it has probably the best sub-header I’ve ever read in a science article: “Grand theft Oort-o?”
- unreal37 12y agoPossibly the farthest away two things have ever been from each other where the word "buzzed" was used to describe their proximity.
- smeyer 12y agoI'd wager the word's been used on galactic scales before.
- S4M 12y agoI am wondering if we could predict those events, and then launch a space probe similar to Voyager I and II that would be hooked in the alien star's gravity and orbiting around it while it travels in the Milky Way, which would be a some free speed for the space probe to explore space further. Now, since stars rarely get that closed, I guess it's a bit pointless but I am still curious about it.
- bdamm 12y agoI wonder if another civilization had this same idea, and dropped a probe off some 70,000 years ago. Or perhaps the probe has yet to arrive, since elsewhere in this thread I see that comets dislodged by the perturbations of the passing stars are yet to arrive at Earth.
- Zelphyr 12y agoI'm curious about what, if any, gravitational effects this would've had on the earth? Seems like its a relatively small star and it was so far away that I'm guessing any pull would've been negligible.
- jontas 12y agoIt is explained in the article: > The effect of a passing star on the Oort Cloud is a function of the star's mass, speed and proximity. The worst case scenario for stirring up comets would be a slow-moving, massive star that came close to the Sun. > Scholz's star came relatively close, but the binary system (the red dwarf and its brown dwarf companion) has a low mass and it was speeding by. These factors conspired to make its effect on the Oort Cloud very small.
- mkempe 12y agoHow long would it take for Oort objects that are nudged out of their orbit to become comets buzzing or hitting Earth? Also, if that star system has its own Oort cloud, could some of the objects there have jumped system and become long-term comets?
- kryptiskt 12y agoThe Nature News article says: "Because Scholz’s star is puny and sped by quickly, it would have had a negligible impact on the Oort cloud, Mamajek notes. And any comets that the star might have sent hurtling towards the inner Solar System will not arrive for another few hundred thousand years, says Tremaine." http://www.nature.com/news/star-buzzed-solar-system-during-human-prehistory-1.16958?WT.mc_id=TWT_NatureNews http://www.nature.com/news/star-buzzed-solar-system-during-h...
- mkempe 12y agoSo the claim that the passage of the star had negligible impact on the Oort cloud (for life on Earth) is an untestable hypothesis.
- ufmace 12y agoThis reminds me of the story "A Pail of Air" [0] where a "dark star" passes through the inner solar system, and its gravity causes the Earth to be ejected from the Sun's orbit. The story features a family who can only survive by maintaining a fire and constantly fetching pails of frozen Oxygen to heat up to breathe and pressurize their living area. I thought of it as one of those things that's extremely unlikely to happen, but we'd be screwed if it did. A little surprising that other start passing through the outer Oort cloud might actually happen semi-regularly, on galactic timescales. Makes the idea sound a little less unlikely, though the inner Solar System seems to have been around for ~5 billion years, and hasn't been disrupted by any star-mass galactic bodies yet. [0] http://www.baenebooks.com/chapters/0743498747/0743498747___6.htm http://www.baenebooks.com/chapters/0743498747/0743498747___6...
- yongjik 12y agoNote that a distant star's ability to "perturb" the inner solar system is basically tidal force: it's the difference in how much the star attracts the Earth vs. the Sun, because if they are pulled by exactly the same acceleration then nothing is changed from the Earth and Sun's viewpoint. So, the effect is proportional to 1/(distance)^3. I guess anything that zips around at ~10,000 AU would basically have zero effect on the inner solar system. And if we reduce the expected distance, the "target area" gets incredibly small. I think we're safe for the time being. :)
- oofabz 12y agoSomeone should run an n-body simulation of the solar system and this star backwards in time to see if it had any perturbative effects on us. What if this star was responsible for ripping Pluto away from a planet or sending Phobos down into the inner solar system to be captured by Mars?