There may be a ninth planet after all.

Beyond Neptune

Scientists have long been hunting for a hidden planet out in the furthest reaches of our Solar System — and new research suggests with even more credibility that it actually is out there.

In two new papers — one published in the Astronomical Journal and another shared but not yet peer-reviewed — the scientists responsible for popularizing the theory of a so-called “Planet 9” argue that the hidden world may have been right under our noses this whole time.

The crux of the theory, as Caltech planetary researchers and paper coauthors Caltech’s Konstantin Batygin and Mike Brown have long claimed, relies on what are known as “trans-Neptunian objects,” or TNOs, that lie beyond the planet of Neptune in the outer edges of our solar system.

As Scientific American notes in its reporting on the new research, the most important of these TNOs is Sedna, a dwarf planet Caltech researchers discovered in 2004 that’s considered the most distant object ever discovered in the Solar System. It has a very wonky orbit respective to the other things that make their way around our Sun, and as scientists began to discover more of these sorts of objects, a pattern emerged that suggested that something was affecting their elliptical axes.

Planetary Gambit

Named as a bit of a joke in the direction of planetary scientists chagrined at the de-planetification of Pluto in 2006, Planet 9 — or P9 as it’s affectionately called — arose as a sort of Schrodinger’s Planet, SciAm explains. What if, as the Caltech researchers began to wonder, a planet was affecting the orbits of TNOs?

Thus far, nobody has directly observed such a planet, but in the new papers that both deal with the search for P9, Batygin and Brown maintain that after looking at more and more TNOs, the best and simplest explanation for their strange orbits is that they’re caught up in the “gravitational perturbations” of a planet we haven’t yet spotted.

The next steps, as the researchers behind the papers urge, is to utilize the power of the next generations of space observatories to try to find it — though as they caution, it still may be a while before P9, or whatever is affecting the TNOs, is detected.

In particular, Batygin, Brown, et al are excited about the upcoming Vera C Rubin Observatory in Chile, which is slated to be turned on in 2025 and will “be sensitive to all but the faintest and most northern predicted positions,” as they predict in the Astronomical Journal.

“This upcoming phase of exploration,” they wrote in the arXiv paper, “promises to provide critical insights into the mysteries of our solar system’s outer reaches.”

More on our home galaxy: Ancient Structures Wound Together to Form Our Galaxy, Astronomers Find

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