Our solar system is known to host eight planets – with Pluto controversially demoted to dwarf planet status in 2006. However, recent astronomical calculations suggest that Earth might have an additional, hidden neighbor lurking in the distant Oort cloud.
Astronomers have determined there’s a 7% chance that an undiscovered planet resides in the Oort cloud, a spherical region of ice chunks and rocks located tens of thousands of times farther from the sun than Earth. Nathan Kaib, an astronomer at the Planetary Science Institute and co-author of the study, stated, “It’s completely plausible for our solar system to have captured such an Oort cloud planet.”
These hidden worlds represent “a class of planets that should definitely exist but have received relatively little attention” until now, according to Kaib.
If such a planet exists, it’s likely an ice giant. Large planets like Jupiter and Saturn typically form in pairs. However, their substantial gravitational forces can sometimes destabilize one another, potentially leading to one being expelled from the solar system or relegated to its outer regions, where the Oort cloud is located.
“The survivor planets have eccentric orbits, which are like the scars from their violent pasts,” explained Sean Raymond, lead author and researcher at the University of Bordeaux’s Astrophysics Laboratory. Consequently, an Oort cloud planet could have a significantly elongated orbit, unlike Earth’s near-perfect circular path around the sun.
Despite the tantalizing possibility of a hidden planet, spotting it is an enormous challenge. “It would be extremely hard to detect,” said Raymond. Malena Rice, an astronomer at MIT not involved in the study, added, “If a Neptune-sized planet existed in our own Oort cloud, there’s a good chance that we wouldn’t have found it yet.” She noted that “amazingly, it can sometimes be easier to spot planets hundreds of light-years away than those right in our own backyard.”
As our technology and methods for detecting distant celestial bodies improve, the possibility of finding an elusive Oort cloud planet becomes more feasible. Until then, astronomers and enthusiasts alike might be inspired to look to the skies with renewed curiosity. Who knows? The ninth planet of our solar system could be waiting to be discovered in the distant reaches of the Oort cloud.
