Two Planets May Lurk Beyond Pluto

It might soon be time to change all those grade-school dioramas of the solar system again: Astronomers think at least two more planets exist, reports Universe Today. In two studies from the UK and Spain, scientists say the planets' existence is the only way to explain why objects are behaving as they are in the nether regions beyond Neptune (and recently demoted non-planet) Pluto, reports Smithsonian. These objects—called extreme trans-Neptunian objects, or ETNOs—should be zipping around randomly but are instead doing so with "unusual symmetry," in the words of Discovery.

“We consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto,” says an astronomer from Complutense University of Madrid. It's just a theory at this point, and EarthSky points out two issues: "First, their proposal goes against the predictions of current models on the formation of the solar system, which state that there are no other planets moving in circular orbits beyond Neptune." (The astronomers suggest other research is disproving this anyway.) And second, the study sample of just 13 objects is small. More research on ETNOs is coming soon, however. “If it is confirmed, our results may be truly revolutionary for astronomy,” says the Madrid astronomer. (Earth, meanwhile, isn't doing well in a new report card of sorts.)