A newly discovered object could bring astronomers one step closer to finding the elusive Planet Nine, a hypothetical super-Earth that is allegedly lurking in the outer reaches of the solar system.
This mysterious object, dubbed 2015 BP519, is a rocky body with an unusual feature: its orbit has a 54-degree tilt with respect to the plane of the solar system, Quanta Magazine reports.
Although this is not the first time that astronomers have uncovered objects with a bizarre orbit — in fact, the very existence of Planet Nine is inferred from the peculiar orbits of a small number of worlds in the Kuiper Belt; this new object and its unique orbit bring substantial evidence that makes Planet Nine appear more tangible than ever before.
Regarded as the “missing super-Earth,” Planet Nine is an ice giant presumably located beyond the Kuiper Belt, at a staggering distance from the sun, 20 times larger than that of Neptune. The existence of this very distant planet, estimated to be 10 times more massive than Earth, was theorized in a 2016 study by two Caltech planetary astrophysicists, Konstantin Batygin and Mike Brown.
Among their arguments in support of Planet Nine, the two astronomers cited the aforementioned few Kuiper Belt objects, only six in number, which are tilted “about 30 degrees ‘downward’ compared to the pancake-like plane within which the planets orbit the sun,” NASA’s Jet Propulsion Laboratory at Caltech noted last year in a news release.
Batygin and Brown argued that the six Kuiper Belt objects could be tilted by the gravitational pull of Planet Nine, which would eventually push them into even higher orbital inclinations.
According to Quanta Magazine, astronomers have actually already uncovered a number of alien worlds that orbit the sun perpendicularly to the solar system’s plane. The newfound 2015 BP519 is the first-ever object to be detected between the two orbital inclinations.
Spotted toward the end of 2014, this rocky object is estimated to be almost as big as a dwarf planet and was picked up by the Dark Energy Survey’s telescope, an international project that studies dark energy in order to measure the expansion of the universe.
Described in a paper hosted by the arXiv server, 2015 BP519 is seen as an important piece of evidence in support of Planet Nine’s existence, because its puzzling 54-degree-tilted orbit can’t be explained unless the hypothetical ice giant is factored into the equation.
“It’s not proof that Planet Nine exists,” study co-author David Gerdes, an astronomer at the University of Michigan, said in a statement. “But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine.”
The team has spent the last few years tracking 2015 BP519’s orbit and trying to figure out where this large space body came from. To uncover the object’s origin, the astronomers performed computer simulations of the solar system that ran 4.5 billion years both into the past and the future and found nothing that could explain how 2015 BP519 landed into its 54-degree tilted orbit, except for Planet Nine.
“The second you put Planet Nine in the simulations, not only can you form objects like this object, but you absolutely do,” said study lead author Juliette Becker, a graduate student at the University of Michigan.
As she pointed out, the only reasonable explanation for having such tilted objects in the Kuiper Belt would be a strong and sustained influence from Planet Nine, which presumably pushes these worlds away from the plane of the solar system.
“I think the case for the existence of Planet Nine is now genuinely excellent,” Becker pointed out.