Space and Physics
PUBLISHED
4
Something big appears to be warping the orbital plane of the Kuiper Belt. We can’t see it, but if some unobserved beast is responsible, it’s potentially bigger than the planet Mercury, and astronomers may have just detected its influence for the first time.
The idea of an elusive planet hurtling around the outer reaches of the solar system isn't new, and theories regarding a so-called "Planet 9" or "Planet X" have abounded over the past decade or so. However, researchers say this new discovery represents an entirely different celestial body, which they have dubbed "Planet Y".
Located somewhere beyond the orbit of Neptune, this mysterious object lies within the Kuiper Belt, a ring-shaped region of space in the outer solar system. Populated by thousands of icy, rocky bodies, the Kuiper Belt is most famously home to Pluto.
Previously, astronomers had noticed that the orbits of some Kuiper Belt objects appear to be clustered, suggesting they may be under the gravitational influence of a huge planet beyond the belt itself. It’s this hypothetical object that is usually referred to as either Planet 9 or Planet X.
The authors of the new study, however, decided to look for variations in the orbital plane of the Kuiper Belt itself in order to learn more about the secrets it might contain. By tracking the orbits of more than 150 Kuiper Belt objects, they determined that the belt’s plane is roughly similar to that of the inner solar system at distances of 50 to 80 astronomical units from the Sun - where one unit represents the distance between the Sun and Earth.
Between 80 and 200 astronomical units, however, the study authors observed a warp that had previously gone undetected. After running a series of simulations, they found “a planet with mass between that of Mercury and the Earth… to be the most likely cause of the warp.”
“Such a body is distinct in both mass and semimajor axis from the various versions of an unseen planet invoked to explain apsidal clustering in the outer Solar system,” they write, indicating that Planet Y is not the same thing as Planet 9 or Planet X.
Compared with the latter, Planet Y is much less massive and closer to the Sun, the study authors explain. And while we know little else about this possible world, the researchers state that “a body like the one described here could have plausibly been produced in the early history of the Solar system.”
With any luck, we might soon catch a glimpse of this planet - if it exists at all - thanks to the recently initiated Legacy Survey of Space and Time run by the Vera C. Rubin Observatory in Chile.
According to the researchers, this 10-year project could massively enhance our resolution of the Kuiper Belt, and “is expected to confirm or deny the existence of the warp reported here, and might detect the planet that may produce it.”
The study was published in the Monthly Notices of the Royal Astronomical Society.
