Planet Nine?

By: Julian Fahrion

Earlier this year, Caltech researchers Konstantin Batygin and Mike Brown presented theoretical data pointing towards a ninth planet in our solar system. The pair began their study after several astronomical bodies in the Kuiper Belt, a ring of asteroids and other small bits of rock or ice, were found to have very similar orbits in 2014. Though the idea of a larger planet pushing the smaller bodies with its gravity was considered, it was not seriously examined. Brown and Batygin set out to put the idea of a ninth planet to rest, but they ended up finding that a large planet with an abnormal orbit would not only explain the orbits of the Kuiper Belt bodies, but also the movements of Sedna, a dwarf planet.

This theoretical planet, which has been nicknamed George, Jehoshaphat, or simply “Fatty” by Brown and Batygin, would orbit from approximately 250 to 1200 astronomical units (AU) away from the sun. An astronomical unit is the distance from the sun to the earth, which is about 93 million miles. For comparison, Mars is 1.52 AU away from the sun, Neptune is 30.10 AU, and the man-made probe Voyager 1 is 125 AU. Planet Nine’s orbit would follow a highly elliptical path that takes 10,000-20,000 years to complete. The planet itself is estimated to be two to four times Earth’s diameter, and its gravity would dominate a wide area of the solar system, prompting Brown to call it “the most planet-y of the planets.”

However, NASA has been quick to say that Planet Nine is still theoretical. Until its existence is confirmed with images, Batygin and Brown’s idea remains an unverified hypothesis.

The difficulty of finding Planet Nine depends on its location. If it is near its perihelion, the part of its orbit closest to the sun, it will be relatively easy for astronomers to find. If it is closer to its aphelion, the portion of the orbit farthest from the sun, only the strongest telescopes will be able to find it. The Subaru Telescope has the potential to locate Planet Nine, and the powerful James Webb Space Telescope, which is scheduled to launch in 2018, could spot the small amount of light reflected off of Planet Nine’s surface.

The idea of a huge discovery in our own solar system has sparked the interest – and criticism – of both experts and non-scientists around the world. Brown himself made a blog post entitled “Why Planet Nine might not exist” that points out various areas where the theory could be wrong. Nevertheless, people are hopeful for a new planet, and searches have already started.

“We hope that other people are going to get inspired and start searching,” Brown said.

Whether from hope, doubt, or sheer curiosity, the idea of Planet Nine has inarguably motivated humankind to take a second look at our own solar system.


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