There just might be an ice giant planet hiding in the outer reaches of our solar system

You likely acquired knowledge while growing up that there are nine celestial bodies revolving around the sun—or eight, subsequent to the notorious downgrade of Pluto. However, what if an additional planet concealed itself in the far outer regions of our solar system?

Astronomers have demonstrated in a recent paper accepted by the journal MNRAS Letters that there could be more than just comets present at the outermost regions of the solar system. In reality, they have computed a 7 percent probability that Earth possesses an additional neighboring planet concealed within the Oort cloud, an area filled with icy fragments and rocks where comets reside. The Oort cloud is incredibly massive and distant: Its border is tens of thousands of times more distant from the sun compared to Earth’s proximity to our star. The researchers’ computer simulations indicate that approximately one out of every 200 to 3,000 other stars is likely to possess one of these distant planets as well.

Nathan Kaib, an astronomer at the Planetary Science Institute and co-author of the study, suggests that it is entirely possible for our solar system to have successfully trapped a planet from the Oort cloud. He further highlights that these unknown entities belong to a group of planets that are undoubtedly feasible, yet have not garnered much focus until recently.

In the event that there exists a celestial body within this nebula, it would most likely be an icy behemoth. When massive celestial bodies such as Jupiter, Saturn, Uranus, or Neptune come into being, they emerge as twin entities. The predicament lies in the fact that these substantial worlds possess a considerable gravitational force, and akin to bickering siblings, they frequently collide with one another. These slight impacts create instability within the nascent solar system, occasionally resulting in the expulsion of a planet—either forcefully ejected from the system entirely or perhaps banished to the outskirts with a few peculiar orbital idiosyncrasies that indicate its journey.

“The survivor planets have eccentric orbits, which are like the scars from their violent pasts,” states Sean Raymond, the primary author and investigator at the Astrophysics Laboratory in the University of Bordeaux. Consequently, the banished planet in the Oort cloud would not only be situated at a significant distance from its star but would also possess an elongated trajectory, similar to the elliptical orbit of a comet, contrary to the almost flawless circle that Earth follows around the sun. The vast separation is also precisely why we have not yet observed such a planet. If it does indeed exist, it would be exceedingly faint. “It would be extremely hard to detect,” Raymond further explains.

Malena Rice, an MIT astronomer not affiliated with this study, concurs that if a planet the size of Neptune resided in our Oort cloud, it is highly likely that we have not yet detected it. Astonishingly, it can occasionally be simpler to observe planets located hundreds of light-years distant than those in close proximity to us.

Despite the challenge, astronomers have been exploring the Oort cloud (and the closer Kuiper Belt) for many years, with the aspiration of discovering the mysterious “hypothetical Planet X.” Planet X, alternatively referred to as Planet Nine—to the displeasure of Pluto’s devoted followers—is a Neptune-sized planet believed to revolve 60 billion miles away from the sun. Astronomers from Caltech, Mike Brown and Konstantin Batygin, utilized observations of objects in the Kuiper Belt to deduce that an entity of equivalent mass as Planet X must be guiding these objects into the observed configurations, but this hypothesis is yet to be verified.

Regrettably, the Oort cloud celestial body from Raymond and his group couldn’t be the identical Planet X that Brown and Batygin have been pursuing. Despite the fact that this alleged Oort cloud celestial body would be distant and possess an elongated, irregular path, that is where the resemblances cease. “The Oort cloud celestial bodies in our models would be considerably more remote than the proposed Planet Nine trajectory—at minimum 10 times farther away,” clarifies Kaib. “Our models cannot situate celestial bodies on Planet-Nine-like trajectories.”

There might be a duo of planets awaiting our discovery in the outer region of the solar system, in addition to numerous others revolving around various stars. Rice states, “These findings emphasize the vast amount of unexplored territory in exoplanet systems, as well as within our very own solar system.”