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Astronomers spot a possible interstellar comet

A fuzzy view of a comet in deep space
Comet C/2019 Q4 seen on September 10. Photo: Canada-France-Hawaii Telescope

Astronomers think they've found an interstellar comet on its way through our solar system.

Why it matters: If confirmed, this will be only the second interstellar object on a track through the solar system found by scientists, and it could help researchers learn more about how star systems beyond our own form.

Where it stands: This comet — called Comet C/2019 Q4 (Borisov) — was first seen by amateur astronomer Gennady Borisov on Aug. 30, and it's expected to come within about 190 million miles of the Sun in December, according to NASA.

  • Scientists around the world will now likely start observing the comet to nail down its orbit and learn all they can about the newfound object.
  • "Absent an unexpected fading or disintegration, this object should be observable
    for at least a year," the Minor Planet Center wrote in a circular.
  • NASA expects that the comet will enter the inner solar system on Oct. 26, when it flies in from above, crossing the plane where the planets orbit the Sun.
  • At the moment, measurements suggest that the comet is between 1.2 and 10 miles across, NASA said, but further observations could refine that estimate.
An orbit map showing the path of an interstellar comet through our solar system
Gif: NASA/JPL-Caltech

Background: The first interstellar object spotted by scientists came through the solar system in 2017.

  • Named 'Oumuamua, the object was found by the University of Hawaii's Pan-STARRS1 telescope while it was on its way out of the solar system.
  • Unlike 'Oumuamua, scientists will have plenty of time to study C/2019 Q4 over the coming months as it makes its way toward the Sun.
  • "This gives us precious opportunity to look at things from another solar system up close, it will help us to understand the formation and evolution of planetary systems in general, including our own solar system," Quanzhi Ye, of the University of Maryland, told Axios via email.

The big picture: Astronomers think interstellar objects like these could have been ejected from their own solar systems through interactions with planets or other objects.

  • According to NASA, an object like 'Oumuamua likely passes through the inner solar system once per year.

What's next: In the coming weeks and months, scientists will try to learn more about the comet, figuring out its size and trajectory, and possibly even examining the light emitted by its atmosphere to learn what it might be made of.

Editor's note: This story has been updated to include new information from NASA.