Astronomers said on Monday that they had identified another invasive asteroid.

Unlike Oumuamua, the cigar-shaped rock that caused a sensation when it cruised through the inner solar system and right back out toward interstellar space last winter, however, this asteroid has taken up permanent residence among us, according to a new study published Monday in Monthly Notices of the Royal Astronomical Society: Letters.

The asteroid, known as 2015 BZ509 — “BZ” for short — was discovered in 2014 sharing orbital space with Jupiter, making a circuit of the sun about every 11.6 years. But it goes around the sun in the opposite direction of Jupiter and the other planets — in a so-called retrograde orbit. The only reason it can avoid banging into Jupiter is that its orbit is egg-shaped and so the rock slips inside and then outside of the giant planet’s orbit as it goes around.

Fathi Namouni, of the Observatoire de la Côte d’Azur in France, and his colleague Helena Morais, of the Universidade Estadual Paulista in Brazil, were trying to figure out how the asteroid got that way, when they discovered that it couldn’t have gotten to where it is, at least according to the history of the solar system as we understand it. BZ had to have been an outsider from the start.