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  Fireballs yesterday and 70,000 years agoFeb 18, 2015 11:49 PM PST | url
Added 1 new A* page:Things flying at us from space! Or through space, anyway! Just the other night, an estimated 250 kg meteor from the asteroid belt put on a pretty good show as it exploded right over one of NASA's observing All Sky Fireball Network cameras near Pittsburgh, and you can see the brief bedazzlement the camera captured in video right here.
And just 70,000 years before that, a red dwarf star and its binary partner, a brown dwarf, passed through the outer Solar System—out around the outer part of the Oort Cloud, about 0.8 light years from the Sun. This is based on the calculated current trajectory of the red dwarf in question: Scholz's star, which is now about 20 light years away from us. Scholz and its companion, about 86 and 65 Jupiter masses, respectively (totaling about 0.15 solar masses between the two of them), are thought to be too small and too fast to have had much of an effect on the "trillions" of potential comets floating around out in the Oort Cloud (and anyway any such comets would take 2 million years to reach the inner solar system : o), and Scholz would have been too dim (apparent magnitude 10.3) to have been visible to the naked eyes of any of our ancestors who happened to be looking up at the time, but still this calculation is a vivid reminder of the kind of stuff flying around not-always-so-far-out in space! In fact, scientists estimate that a star probably passes through the vast reaches of the Oort Cloud about once every 100,000 years, but one coming as close as Scholz's did might happen only once every 9 or 10 million years (although I'm a little confused by this statement made both by the BBC article and Wikipedia, since the outer Oort cloud only goes out to 0.8 ly, ie about the same distance as Scholz is said to have reached : P). Wikipedia adds that there are about 100 star systems within 21 ly of the Sun.
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