Planet 9: Closing In On The Mysterious Planet At The Edges Of Our Solar System

Planet 9, the hypothetical planet that lurks at the outskirts of our solar system, may be coming into focus in the near future, thanks to the efforts of scientists around the world. New theories are emerging about the potential location and even the possibility that there are two or more as yet undiscovered planets orbiting the sun beyond Neptune.

Back in January, scientists Mike Brown and Konstantin Batygin of Caltech released their evidence for the existence of Planet 9. The two planetary scientists began by examining the orbital patterns of the six most distant objects in the Kuiper Belt, a region populated by asteroids and dwarf planets – including Pluto – that lies beyond Neptune in our solar system. Certain anomalies in these orbits suggested that the six Kuiper Belt objects (or KPO) were responding to the gravitational pull of a single source – potentially Planet 9. Mathematical models suggested that Planet 9 would be up to 20 times larger than earth.

Brown and Batygin have continued to analyze and work with the data and the two planetary scientists published their latest findings in the June 20 issue of Astrophysical Journal Letters. They believe that Planet 9 is about 500 to 600 times farther from the sun than earth, or up to 250 billion kilometers away, and that its orbit is both stretched into an oval and tilted at a 30 degree angle as compared to the rest of the solar system. That means its orbit would take it both above and below the orbits of the other eight planets, and explain in part why it has not been viewed so far. It is also believed that Planet 9 lies in a part of the sky around the constellation Orion.

Planet 9, 10, And 11?

One of the newest theories about Planet 9 is that it is, in fact, not just one planet but a cluster of planets. As reported in the Daily Mail, two freelance Spanish astronomers, Carlos and Raúl de la Fuente Marcos, together with scientist Sverre J. Aarseth from the Institute of Astronomy of the University of Cambridge, looked at the same data. Their calculations showed that the orbits of the six KPO would become unstable within 10 million years, leading them to eventually escape the solar system entirely. The researchers theorize that one or more additional planets acting in mutual resonance could be responsible for stabilizing their orbital paths.

The International Hunt For Planet 9

Teams of astronomers from around the world are searching for the elusive Planet 9. Renu Malhotra and his colleagues at the University of Arizona in Tucson have also been examining the data and point out that the six KBOs are not only responding to a similar pattern, but are more or less in sync with each other.

Scott Sheppard, a planetary scientist at the Carnegie Institution for Science in Washington, D.C. and Chad Trujillo, of the Gemini Observatory in Hilo, Hawaii, are looking for Planet 9 by looking for the farthest KPO. Their research suggests that these objects are all following roughly the same orbital alignment.

As the various scientific teams zero in on Planet 9's location, the latest technology, including the Subaru telescope in Hawaii, means they may be able to actually – and finally – view it. So far from the sun, Planet 9 would be extremely cold and theories suggest it may be composed largely of hydrogen and helium. Jonathan Fortney, a planetary scientist at the University of California, Santa Cruz, is quoted in Science News.
"We expect the planet, if it's there, to be a kind of mirror. We think it would be bright with a whitish hue."
His report is published in June 20 issue of Astrophysical Journal Letters.

At the Paris Observatory in France, a team working under Professor Jacques Laskar is attempting to calculate Planet 9's position and then turn their instruments to viewing it. As reported in the Daily Mail, researchers at Lund University in Sweden have developed a theory that Planet 9 is actually an exoplanet from another star that was "stolen" by our sun when it was younger.

According to a story in Wired, another group from Harvard-Smithsonian Center for Astrophysics is using data from NASA's Cassini mission, currently orbiting Saturn, to calculate the distance from Cassini back to ground stations on Earth. The figures are then extrapolated to help pinpoint Planet 9's location. With so many teams on the hunt, some controversy is perhaps inevitable. According to the Daily Mail, NASA has played down the concept, suggesting that any anomalies in Cassini's data are due to minor errors.

The evidence is intriguing, but nonetheless slim. Renu Malhotra, a planetary scientist at the University of Arizona in Tucson is quoted in Science News.

"The argument that a planet is there is not ironclad."
With the latest in viewing technology and teams of researchers from the top facilities around the world on the case, there may be a definitive word on Planet 9 and its location sooner rather than later.

[Image via Caltech/R. Hurt (IPAC)]