When scientists measure the orbits of the planets of the solar system, they use known laws of the universe to predict the paths those planets will take. A variance between the motion predicted and the motion observed suggests that something's unaccounted for is going on, sending scientists into fits of glee as they uncover whole new arenas of knowledge. As this Live Science story points out, variations in planetary orbits helped Albert Einstein confirm his theory of relativity (Mercury wasn't behaving) and led to the discovery of Neptune (Uranus wasn't behaving -- and no, I'm not sorry).
Well, a bunch of "trans-Neptunian objects" or TNOs are orbiting oddly enough that what we know about the solar system right now doesn't explain it. Astronomers have postulated a faraway Planet Nine whose gravitational pull is affecting them, although this proposed body has not been sighted.
One new theory is that what we're seeing is being orchestrated not by a planet but by one of the extra-small black holes left over from the early days of the universe. Black holes today require at least 10 times the mass of the sun to form, and such an object would have already been detected if it was there. Conditions in the early universe allow for the possibility of a black hole with a smaller mass, although they have never been observed and are still hypothetical. If Planet Nine turned out to be one, it would be an amazing chance to study an object dating back billions of years. Hence the excitement at the possibility, expressed in the article's headline: "What if Planet Nine Is a Baby Black Hole?" There's just one problem, of course, that the article writer erroneously overlooks.
PLANET NINE IS PLUTO, DAGNABBIT!
I await both the correction and credit for discovering the error.