Now Brown and his co-author, Konstantin Batygin, believe they've compiled the best evidence for a true ninth planet to take Pluto's place in the history books. Most members of the general public probably don't know about all of the planetoids he has found — but many know about the one planet he has killed. If outrageously calling myself 'Pluto killer' helps people understand what the solar system is really like then I'm happy with it Dr Mike Brown, Caltech 
 
 "There is no other way of categorising our Solar System than to describe it as having eight dominant objects in it which are the planets we know. Instead, they have inferred its existence from the motion of recently discovered dwarf planets and other small objects in the outer solar system. Mike Brown and Konstantin Batygin stand for a portrait in front of an artist portrayal of Planet Nine at Caltech (Photo by Patrick T. Fallon for The Washington Post) 
 
 "Until then, we didn't really believe our results ourselves. MB: I think that there are people who would still love for Pluto to be a planet, and they wish people who kept reminding them why it’s not would be quiet and go home. MB: It all happened kind of accidentally back in the early days of Twitter. The gas giant is thought to be almost as big as Neptune and orbiting billions of miles beyond Neptune's path — distant enough to take 10,000 to 20,000 years to circle the sun. WP: So size isn't really the thing to get hung up on? One of the trickiest criteria for planet status, based on the standards set by the International Astronomical Union, is that a planet must "clear the neighborhood" around its orbital zone. The "Pluto killer" added: "Not to mention the fact that it's 5,000 times the mass of Pluto." Read More: 
 
 Nah, this possible new ninth planet isn’t Pluto 
 
 Q&A: The ‘Pluto Killer’ who thinks he’s found the true ninth planet 
 
 Flashback to 2004: Mike Brown discovers "Sedna" 
 
 This is what it looks like when a black hole tears a star apart 
 
 This broken space telescope keeps spotting new planets 
 
 Why NASA’s top scientist is sure that we’ll find signs of alien life in the next decade 
 
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– Pluto is gonna be PO'd. While the dwarf planet tries to fight its way back into the good graces of Those Who Deem What Counts as a Planet, another icy orb even further out may snatch that designation first. Astronomers at the California Institute of Technology say a giant celestial body "lurking at the end of our solar system," as the Washington Post puts it, may actually be a planet, and they're even already calling it "Planet Nine." In their research published in the Astronomical Journal, the sky-watching scientists—one of whom is known as the "Pluto killer" for his role in getting Pluto demoted—think their find is five to 10 times as massive as Earth, and per the AP, almost as big as Neptune and orbiting billions of miles past that planet's orbit. Michael "Pluto Killer" Brown and Konstantin Batygin haven't seen the supposed planet directly, but say they can infer the "massive perturber" exists by how the orbits of smaller bodies nearby are affected by its gravitational pull, the Post notes. What's interesting is that Brown and Batygin originally set out to disprove the existence of Planet Nine. "We thought their idea was crazy," Brown says of the scientists who originally floated the idea of a large, hidden planet. But as they did their own research, they soon came to their own conclusion in what Brown calls a "jaw-dropping moment" that Planet Nine could be the real deal. Now they're simply hoping more astronomers join in to actually try to spot the alleged planet—and they're not concerned it will face Pluto's fate. "That's not even a question—it's definitely a planet," Brown says. Not everyone's convinced. "I have seen many, many such claims in my career," a planetary scientist at Colorado's Southwest Research Institute tells Nature. "And all of them have been wrong." (The Washington Post caught up with Brown for a Q&A on the latest Pluto-killing endeavor.)