Is it possible that meteoroids, comets, asteroids or other small bodies from around a nearby star (such as Alpha Centauri) could get into the solar system?

How low is that possibility?


Since the Oort Cloud is not being gravitationally attracted enough to the Sun to form a disk, I assume this is the same for Alpha Centauri's Oort cloud. Therefore, my question is: can the Sun gravitationally pull a comet from Alpha Centauri's Oort cloud?

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    $\begingroup$ Some of these comets probably shed rocks on their way through the solar system: List of hyperbolic comets: en.wikipedia.org/wiki/List_of_hyperbolic_comets Jupiter probably slowed some of those rocks down. $\endgroup$ Nov 2, 2016 at 13:24
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    $\begingroup$ The Oort cloud not forming into a disk is not because it is not "being gravitationally attracted enough to the Sun". I think the short answer to your question is it is highly improbable. A full answer verifying that improbability could end up being an entire published paper on the subject and likely too much work for anyone here to undertake. $\endgroup$
    – zephyr
    Nov 2, 2016 at 18:34

1 Answer 1


Most, and perhaps all, stars form in stellar clusters. Most likely, the sun formed in a open cluster. In clusters the density of stars is quite high, therefore close encounters are common. So, I think it would be quite likely for such close encounters to disturb Oort clouds enough to send comets out of their host systems. Some small fraction of these comets would be recaptured by other stars within the open cluster.

In addition, it is thought that in the early period of planetary disk formation, there were many more planets than today, but they often collided with each other, often sending pieces out of the stellar system. Moreove, many small planets and asteroids were thrown out by gravitational interactions with the large planets (see Tremaine). These 'debris' would be roaming interstellar space. Occasionally, one could fall into any random stellar system.

The odds that we have any asteroids or comets from any particular nearby star is low, unless it happened to have been from the Sun's birthplace. We do not have the ability to determine which of the nearby stars are from the Sun's open cluster, but the Gaia Satellite may make that possible soon. And, if we explore the solar system long enough, we may find exo-solar asteroids among the hordes of asteroids.

  • $\begingroup$ Indeed, the precision of radioisotope dating makes it eminently feasible to identify "odd" pieces of rock, given that stars in a cluster may form over a few million years. $\endgroup$
    – ProfRob
    Nov 7, 2016 at 22:57

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