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How long would it take for an asteroid to travel to our sun-system ?

  1. Mar 21, 2014 #1
    How long would it take for an asteroid to travel to our "sun-system"?

    I have been informed about the rules of the forum, that the administrators strongly encourage members to make an effort on their own first to sought out answers, but that one mustn't do that. I'm very tired of Wikipedia, and good homepages which explain things simple are a bit hard to find. The rules of the forum also says, try to make one question of the time, but it's not a definite rule. The question is how long would it take for an asteroid to travel from another "sun-system" (I don't know the English word. Please tell me what it is. I hope you understand what I mean by sun-system. The system which contains the eight plantes) to ours? Thanks
  2. jcsd
  3. Mar 21, 2014 #2


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    Staff: Mentor

    The nearest star system is about 4 light years away, meaning it takes light 4 years to travel one way between us. At even the highest realistic velocities it would still take hundreds of thousands of years if not more for an asteroid to travel from one star system to another.
  4. Mar 21, 2014 #3


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    How long it would take, depends on how fast it is traveling. We can assume that said asteroid would have been kicked out of its own star system by interaction with the other planets of the system. Much like the Voyager probes were boosted by close passages to planets.

    Voyager 1 is traveling about 17 km/sec, so we'll use this speed as a base assumption. As already stated, the nearest star system is 4.3 light years away, so at 17 km/sec it would take ~75882 years to travel that far.

    But This isn't the end of the story. You see, the stars themselves have relative motions with respect to each other and these velocities are comparable to the 17 km/sec speed of Voyager itself. For example, Alpha Centauri, the closest star system, has a radial velocity of 21 km/sec towards our solar system. If Voyager were on a course to intercept Alpha Centauri (Which it isn't), the two would actually meet in ~33947 years.

    The various motions of the stars can have a large impact on travel times.
    For instance, on it present course, Voyager I will pass within a couple of light years of a star system which is presently 17.6 light years away in ~40,000 years, Now this seems a fairly short time, since it would take almost 34,000 yrs to reach a star system which is now 4.3 light years away. The short time is due to the fact that this star system is moving towards us at 119 km/s, so most of the 17.6 light years will be eaten up by its traveling towards us. ( I should point out that these radial velocities do not mean we have to worry about colliding with these star systems at some future date, as their motions also include a "sideways" or proper component. )
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