Apr 28, 2020 - Science

Interstellar asteroids in our backyard

The aurora above Earth.
The aurora above Earth. Photo: NASA

A population of asteroids captured from other stars could be lurking in our own solar system, a new study contends.

Why it matters: Interstellar asteroids and comets represent astronomers' best chances of studying an object from another star system at close range, potentially revealing how unique (or average) we are in the process.

Details: So far, scientists have spotted two interstellar objects — Comet 2I/Borisov last year and 'Oumuamua in 2017 — but finding a population of these bits of debris from other stars in our own solar system could be a game-changer for researchers.

  • The new study, published in the Monthly Notices of the Royal Astronomical Society, suggests about 19 asteroids with odd orbits in the outer solar system could have been captured from other stars billions of years ago in the early days of the solar system.
  • “The close proximity of the stars meant that they felt each other’s gravity much more strongly in those early days than they do today,” Fathi Namouni, lead author of the study, said in a statement. “This enabled asteroids to be pulled from one star system to another.”
  • Instead of being forced to wait until another interstellar object is spotted whizzing through our part of the galaxy, astronomers could study this population of asteroids more easily.

But, but, but: The origin of these asteroids may not be interstellar at all.

  • The modeling done for this study doesn't take into account all variables that may have led to the positions of these objects in our solar system, potentially skewing the results.
  • "This is an interesting thing to study because we still don't have a great explanation for how you can get things onto these orbits," planetary scientist Kat Volk, who is unaffiliated with the new study, told Axios. "But I don't think that it was solved now by this paper."

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