On the Science channel today on Complete Cosmos the approach of Barnard's star is shown (probably by computer simulation). It will not collide.<br /><br />Anyone have a time frame for this upcoming event?<br />
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So has anyone wondered or done a study on whether Barnard's or some other star in our neighborhood passes by like this on a regular basis? Say in some huge multi-million year elliptical orbit?<br /><br />The fossil record contains evidence of mass extinctions every 30 or 60 million years. Wouldn't that perturb the Oort cloud causing a swarm of comets to come crashing into the inner solar system? I know a lot of these would miss us and probably get eaten up by the Sun or Jupiter (hello, Shoemaker Levy 9), but seems like 1 could hit us. Ouch!
There are a few other stars that are approching Earth ,but they are coming slower from farther away than Barnard's star, which will like perturb our Comets less than the centari system, which has about15 times the gravity of Barnard's star. Likely a star comes within about three light-years two or three times per billion years, which isn't often enough for mass extintions at 60 million year intervals. Neil
Thanks, nexium. I didn't even think to compare the mass of Barnard's vs Centauri.<br /><br />Curious about the "2 or 3 times per billion years" stat though. Is that based on observation (of known star paths nearby) or theory? I do remember now seeing a documentary saying our sun bobs up and down through the galactic ecliptic plane on about that period, but zero explanation as to the orbital mechanics of that.
spaceJunki - HI! Well, yes, there have been studies done. With varying results considering varying parameters.<br /><br />Remember, not all stars are visible. Brown dwarfs would likely be invisible, for example.<br /><br />There have been studies indicating a 10th planet, a supergiant larger than Jupiter but smaller than a brown dwarf, is even now perturbing orbits in the Oort cloud.<br /><br />Others dispute this as the cause.<br /><br />Some do consider the cycle of perturbations which may include the extinction of the Dinosaurs to be caused by close encounters (not of the third kind, btw). <br /><br />One should also be careful about quoting dating estimates as gospel. One must consider the method and other details leading to the conclusion.