Astronomers have found compelling evidence of an unseen 9th planet in our solar system

Rick Stella

After work done by Caltech professor Mike Brown led to Pluto’s famous plantary demotion in 2006, the esteemed astronomer is back in the headlines this week with one hell of a reported finding. Published in The Astronomical Journal, Brown’s (in conjunction with Caltech assistant professor Konstantin Batygin) report states that recent analysis done of our solar system suggests the presence of a planet ten times as massive as Earth located some billions of miles beyond Pluto. Though Brown and his colleagues have yet to actually detect the planet (of which they’re dubbing “Planet Nine”), all relative evidence points towards its existence.

Before Brown and Batygin’s recent discovery, theories of a long lost ninth planet (sorry, Pluto) began circulating among the astronomer community back in 2014. Gemini Observatory’s Chad Trujillo and Carnegie Institution of Science’s Scott Sheppard reported sightings of smaller planetary objects in the same area of the solar system and posited that it was likely something planet-sized lurked in the area. During their analysis, the scientists noticed a particularly odd occurrence regarding the orbit patterns of their discovered objects.

Following extensive research, the duo were able to argue that the object’s obscure orbit patterns were best analyzed using what’s called the “argument of perihelion.” Essentially, this notion looks at the amount of time it takes an object to make its closest pass by the sun compared to the recorded time of it crossing the plane of the solar system. Based on the readings Trujillo and Sheppard took from known celestial objects, it became increasingly clear something else was greatly affecting their gravity — i.e. an unknown, large planet.

Artist rendition of "Planet Nine" looking towards the Sun
Artist rendition of "Planet Nine" looking towards the Sun

Artist rendition of “Planet Nine” looking towards the Sun

Caltech/R. Hurt (IPAC)

“We noticed something curious,” Trujillo says in the 2014 report in Nature, “and said ‘someone should go explore this further.”

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With this information already recorded, Brown and Batygin stepped in to see what they could find. Initially, the pair noticed that each of the object’s orbits register in the same area of the sky, meaning they’re all pointing in the same direction. Closer examination revealed that each object’s orbit not only featured similar arguments of perihelion but closely aligned elliptical orbit patterns as well, making it increasingly evident something else was greatly influencing their paths. Like a light going on, Brown says it was “ridiculous” something of this nature had yet to be discovered.

“Shouldn’t something like this be hard to miss?” Brown questions in the findings. “Yes, you would think so. This is a case where we had our noses buried in the data, never stepping back and looking at the solar system from above. I couldn’t believe I’d never noticed this before.”

Brown goes on to admit it wasn’t the initial intent to assume the signs pointed to an actual planet, calling the idea “crazy.” Instead, research and analysis focused on deciding if the Kuiper Belt actually deposited some of these objects which, over time, would create a massive cluster. However, it was quickly determined the Kuiper Belt lacked the available mass to create such an object capable of influencing orbit patterns of the magnitude detected, moving the scientists to put the seemingly ludicrous idea of another planet back on the table. A series of simulations proved the “crazy” theory to have traction, producing the correct type of aligned orbits to what was actually discovered.

Caltech professor Mike Brown and assistant professor Konstanin Batygin
Caltech professor Mike Brown and assistant professor Konstanin Batygin

Caltech professor Mike Brown and assistant professor Konstanin Batygin

Lance Hayashida/Caltech

As mentioned above, scientists say the assumed ninth planet is likely about ten times as massive as Earth, meaning it fits into the category of being a “super-Earth.” Before the recent discovery, scientists have deemed several planets as being a super-Earth, however, none have ever existed within our solar system. Though little is currently known of the planet’s actual orbit or size, it’s suggested that its likely orbit would only ever bring it to within roughly 19 billion miles from the sun (and roughly three to six times further at its furthest orbit point). As Brown and Batygin continue analyzing the thrilling findings, Brown hopes he’s the first to physically see it.

“I want to know what it’s like. I want to see that it’s really there,” says Brown. “It will hurt when somebody finds it and it’s not me — but I assume it’s going to happen, and I’m willing to feel the pain.”

Feasibly, only the Japanese Subaru Telescope in Hawaii possesses the capability of detecting the distant planet, boasting a giant mirror adept at pinpointing distant light as well as an incredibly wide field of view. Though it’s likely Brown won’t be the first to lay eyes Planet Nine (neither he or Caltech own the Subaru), the scientific community won’t give the object a definitive planetary ruling until someone physically sees it. As SwRI researcher Hal Levison puts it, he’s “seen many, many such claims” in his career, “and all of them have been wrong.”