Meet Planet X, The ‘Killer’ Giant Lurking At The Edge Of Our Solar System

Artist's impression of Planet Nine as an ice giant eclipsing the central Milky Way. Image by Tomruen, nagualdesign via Wikimedia Commons

The solar system is a pretty exclusive club—fewer than 10 planets have ever been admitted to the collection of celestial bodies that make up Earth’s little neck of the galactic woods. Famously, in 2006 the most recently discovered member—sweet, icy little Pluto—was controversially demoted from the roster and downgraded to mere “dwarf planet,” leaving us with a mere eight in our circle. (Miss you, P.)

Now it looks like we might actually have a new contender to fill the Plutonian void: The science world has been in a tizzy over the proposed existence of a previously unknown planet, located at the far-flung edge of our solar system. It’s being called “Planet Nine,” or (more mysteriously), “Planet X,” and it’s a big one—potentially 10 times more massive than Earth. Its existence would explain the behavior of a group of icy objects moving through the Kuiper Belt, a region beyond Neptune. And if Planet X is actually out there, the newly discovered orb would take around 20,000 years to complete a single trip around the sun.

But can Planet X ever really be as cool as our last ninth, Pluto? While Venus enjoys a more romantic mythological moniker, only Pluto can lay claim to an actual heart within its terrain. Pluto was there for us through the second World War, the cola wars, Ken Burns’ Civil War, and humanity’s first forays into space. It was the namesake for Mickey Mouse’s dog. It is thought to be connected to H.P. Lovecraft’s Yuggoth, a fictional outer planet from his 1931 story “The Whisperer in the Darkness.” (And don’t forget about the dark area along Pluto’s equator, now dubbed Cthulhu Regio after the author’s most famous creation). It’s a hard act to follow.

Pluto has heart. Image via NASA

At least initially though, it’s looking good for the possible new ninth planet: Both the science and the hype are shaping up rather nicely. For one thing, Planet X is likely to stay in the headlines, as conspiracy theories, controversy, and end-times predictions have already been spun off its proposition. The New York Post, for example, calls it the “killer planet” in an April video, asserting that its “orbit might cause asteroids to come shooting at the Earth.”

And if you’ll just don this tinfoil hat that I’ve prepared for you for a sec—yes that’s right, the shiny side up, keeps the Zeta radiation out—a number of the internet’s top crackpots have attached the new planet to the work of Wisconsinite and self-proclaimed extraterrestrial communicator Nancy Lieder, who asserts a mysterious planet will soon collide with Earth, killing most of our species. (Though Lieder herself says the newly theorized planet is “just a distraction.”) Some are saying the new discovery could even be Nibiru, a cosmic object considered by “ancient alien architect” theorist Zecharia Sitchin to be the home of mankind’s creators, who only come into contact with humanity once every 3,600 years.

These out-there theories might be funny, but they appear to irk Mike Brown of Caltech, one of the researchers who first found evidence for the existence of Planet Nine. He tweeted: “Planet Nine is not going to cause the earth's destruction. If you read that it will, you have discovered idiotic writing!”

See Brown’s Twitter handle there? He goes by “@plutokiller” because he Anne Boleyn-ed Pluto himself over size-related issues. That’s right. The same guy who wrote How I Killed Pluto and Why It Had It Coming, just happened to discover a new planet to take Pluto’s place. Pretty convenient, Brown. The scientist’s lack of sentimentality over dumping Pluto has long been upsetting to the former planet’s fans and well-wishers.

Along with fellow researcher Konstantin Batygin, Brown proposed the existence of Planet Nine through “mathematical modeling and computer simulations,” and though no one has actually seen Planet Nine yet, the search to catch a telescopic glimpse is on. For now, scientists are trying to figure out how, if Planet Nine exists, it originally formed, and how it even got that far out from the sun in the first place. One theory is that Planet Nine was once dragged out by the pull of another passing star. But it seems more likely that Jupiter and Saturn teamed up to bully the theoretical planet to the nether ends of the solar system with a succession of gravitational pushes. (Typical Jupiter and Saturn.)

Prediction of hypothetical Planet Nine's orbit. Image by nagualdesign via Wikimedia Commons

So will Planet X fill the Pluto-shaped hole in our hearts? While the evidence is compelling, we still aren’t even totally sure it actually exists, or if it is in fact, a planet. But the very fact that we’re having this conversation is proof that it’s time to move on. We couldn’t hold on to “my very excellent mother served us nine pizzas” forever. It’s time to get excited about Planet X. Even Brown, cold-hearted destroyer of worlds, seemed to acknowledge the collective yearning to restore the solar system to its former glory.

“All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found,” he said in a CalTech press release about Planet Nine earlier this year. “Now we can go and find this planet and make the solar system have nine planets once again.”