Last month the science sections of various media were ablaze with the “discovery” of a ninth planet in our Solar System. Or at least, that’s the impression one could get when skimming the titles. Some less reputable media I saw in print even had it without a doubt: “New planet discovered in solar system,” trumpeted The Sun.
To be clear, no such planet was discovered. A discovery, especially of a planet in our solar system, would entail photographs or data indicating its existence with a very high degree of certainty. There was no such solid proof. Instead, Professor Mike Brown and Dr. Konstantin Batygin, researchers at Caltech, have published “evidence” that there could be a very large object at the edge of the Solar System (5,000 times larger than Pluto).
The word “evidence” was used in a recent phys.org article about the possible celestial body, and it’s not wrong. But it was not a “discovery.” The two researchers published a mathematical article detailing mathematical modelling that could indicate the presence of such an object. Personally, I wouldn’t call it “evidence” either, but it seems like solid science—even if it turns out they were wrong. Some doubts have already been formulated by other scientists.
The principle of their calculations is that the elliptical orbits of six large objects in the Kuiper Belt (the outermost region of the Solar System, full of small and large icy debris) are all aligned at one end in a highly improbable way. Their orbits are also tilted (with respect to the plane of the other eight planets in our system) in the same way. After trying out several models, they found that a large object traveling a particular elliptical path 13–26,000 billion km from the sun, is a stable model to explain these observations… in a computer.
I don’t want to take away from the science these researchers have done. They seem to have done a decent work, and they are making predictions that can be tested and verified. It won’t be easy to find such a darker object on an orbit that may take 20,000 years to rotate around the Sun, but it is doable. Researchers will be searching for it with the Subaru telescope in Hawaii, and may use other means of direct detection as well. Furthermore, now that the paper is published, other astronomers will vet it, possibly finding errors or corroborating the calculations. That is exactly how science works and how it should work.
It is therefore a bit sad to see media running away with words like “discovery” and “evidence.” The articles would be just as interesting with “calculations show that” and “possible evidence,” and they would at the very least be correct and could avoid the possibility of disillusioning lay readers with unrealistic expectations.
All this reminds me of the early 2000s, where there was talk of a Planet X (there were still nine planets at that time) which didn’t materialise. (Nor did it show up for its first projected appearance in 1995, or subsequent predictions by mystics and conspiracy mongers who claimed it would arrive in 2012, 2013, 2014, or 2015.) Those calculations didn’t take a lot of confounding factors into account, including that the mass of said planet could be distributed around the Sun in the Kuiper Belt. On the other hand, we could have the same situation as when the discovery of Neptune was predicted in the 18th century, or as in 1930, with the prediction and discovery of Pluto—although it later turned out it was a lucky find and didn’t match the calculations. Only time and decent science will tell.