Back in the day, we thought we knew everything there was to know about our solar system.

Then they went and demoted Pluto.

Now, it seems there might be a mystery contender that has been hiding out all this time.

Two new papers were recently published, and both lend credibility to this idea, which has been circulating for some time.

The theory, known as “Planet 9,” argues that a whole planet has existed under our noses since basically forever.

Caltech planetary researchers and coauthors Konstantin Batygin and Mike Brown rely on the idea of “trans-Neptunian objects,” or TNOs, that are out there beyond Neptune.

The most important of these TNOs is Sedna, a dwarf planet discovered in 2004. It has an offbeat orbit, and since this is a pattern among TNOs, the researchers suggest there must be something out there affecting their elliptical axes.

The concept of P9 arose as an explanation – the possibility of a whole planet affecting the orbits of these TNOs.

No one has observed such a planet, but the authors of this paper agree that it’s the simplest and best explanation for these TNOs with strange orbits in the same area.

They want to utilize the growing power of our space observation technology to try to find it. They’re hoping the upcoming Vera C. Rubin Observatory in Chile could help them out.

It’s slated to open in 2025, and will “be sensitive to all but the faintest and most northern predicted positions.”

They believe that tech like this will allow us to see everything that exists, even in the outer reaches of our solar system.

I, for one, am here for it.

But I’m not going to be the one to explain it to Pluto.

If you thought that was interesting, you might like to read about a second giant hole has opened up on the sun’s surface. Here’s what it means.