A little larger than Earth and very far away: new predictions for Planet Nine

A planet one and a half to three times larger than our Earth behind Neptune could explain many of the anomalies in the so-called Kuiper Belt. Two researchers from Japan have calculated this, and at the same time put forward a testable hypothesis for another planet that has been speculated for years as “Planet Nine.” The proposed planet could therefore orbit the Sun at a distance of 250 to 500 astronomical units and on an orbit tilted by 30 degrees, which would be on the outer edge of the so-called Kuiper Belt beyond Neptune. This means the planet will be much farther from the sun than FarFarOut, the previous record holder. Even if it is too far gone for current tools, it is possible to test the theory.

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Not a new proposal, but a more accurate forecast

The new study was presented by Patrick Likaoka and Takashi Ito of Kinki University in Osaka, Japan. It follows previous work that has now been essentially revised. As the two now explain, their hypothetical planet could explain why there are so many objects in the Kuiper Belt that are unaffected by Neptune’s gravity. The planet could also explain why there are many objects with particularly highly inclined orbits and some particularly extreme objects with more eccentric properties. There is already an example of the latter in our master. All of this can be explained by the gravity of a planet similar to Earth orbiting much further away.

Overall, this prediction is not surprising; Simulations have been running for years indicating that there must be another large planet in the Kuiper Belt beyond Neptune. Recently, Mike Brown and Konstantin Batygin of the California Institute of Technology (Caltech) have attracted particular attention with their work on this topic. The two researchers from Japan have now calculated that such a planet – even if it is too distant to detect directly – should ensure the formation of clusters of celestial bodies in the Kuiper Belt at a distance of about 150 AU from the Sun. If this could be proven, it would be indirect evidence of the hypothetical planet. They write in the astronomical magazine.

Just a few weeks ago, three other researchers presented a paper arguing that in addition to a hypothetical ninth planet at the edge of the solar system, there could be a tenth planet farther away. Such a celestial body in the so-called Oort cloud, which has so far been described only hypothetically, at the edge of the solar system would be much larger than “Planet 9” and perhaps comparable to Saturn or Jupiter. The research team also calculated that such exoplanets, particularly far from their stars, should not be rare. However, these predictions cannot be verified, as this potential tenth planet would be very far away.

(meh)