This agrees with recent paper about another planetary candidate, in an orbit which rules out the Brown-Batygin Planet Nine (which you’re calling X).

I don’t think we are in a position yet to say that the Brown-Batygin hypothesis is ruled out. But it is an interesting development, and it does suggest that there’s a lot more out there in the Kuiper Belt and Scattered Disc that we still haven’t found.

We’ll learn a lot more once the Vera Rubin telescope (first light planned for July 2025) is operational.

Michael McNeil: Fixed. Thanks.

David Ross: Minor point: I’m not calling it X, this was the term the researchers used in the paper.

They mention this other work you refer to here, which also suggests this theorized “ninth” planet doesn’t exist. Calling a “ninth planet” is in itself foolish, because this research is showing that there are a lot more than the nine planets known (I include Pluto, as do most planetary scientists). I am willing to bet that a large number of these Kuiper and Trans-Neptunian objects will be large enough so that gravity will forced them into a spherical shape, the definition for a planet that works best for the scientists who study these things.

Thus, our solar system likely has dozens more planets in its outer reaches. We just have to find them.