Asteroid 2015 BZ509 Is First "Interstellar Immigrant" in our Solar System

A super super sneaky object lurking in Jupiter’s orbit has been up to something big.

According to a study published Monday in Monthly Notices of the Royal Astronomical Society: Letters, an asteroid known as (514107) 2015 BZ509 is not actually from our solar system — it’s a visitor whose vacation here will last permanently, much like Jimmy Buffett in his 1977 song “Margaritaville.”

You might be thinking, why this asteroid, right? There are so many of these things,, it’s hard to keep up. But 2015 BZ509 is a bit of a weirdo because it moves in “retrograde” orbit around the sun, meaning it travels in the opposite direction of most objects in our solar system. This gave some scientists pause.

“How the asteroid came to move in this way while sharing Jupiter’s orbit has until now been a mystery,” the study’s lead author Fathi Namouni of the Observatoire de la Côte d’Azur explains in a press release. “If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them.”

2015 BZ509, as seen by the Large Binocular Telescope Observatory (LBTO)C. Veillet / Large Binocular Telescope Observatory

Namouni and her team ran computer simulations to track the asteroid’s movement as far back as 4.5 billion years. They confirmed 2015 BZ509 must have come from another solar system because it’s always moved in this different direction.

Not to be confused with ‘Oumuamua, the first interstellar object to zip through our solar neighborhood, 2015 BZ509 is here to stay. ‘Oumuamua is currently on its way to exit our solar system, passing the gas giants until it blows this proverbial popsicle stand for good.

“Asteroid immigration from other star systems occurs because the sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids,” the study’s co-author Helena Morais of São Paulo State University says in a statement. “The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove, and capture asteroids from one another.”

Right now, 2015 BZ509 is enjoying its 15 minutes of fame, as scientists have declared it the “first interstellar immigrant” discovered in our solar system. This asteroid has built a pretty cushy situation for itself here, even though it will never get to enjoy the true goodness of Jimmy Buffett’s “Margaritaville”. Space rocks don’t drink margaritas.

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