October 25th, 2016 by James Ayre
The past few years have seen a lot of speculation and debate about a possible ninth planet orbiting somewhere on the very out fringes of the solar system. Now, new research from the University of Arizona has provided some further support for the theory.
The research also narrows the possibilities of where such a planet could theoretically be found, and what it would be like.
The new work shows that the 4 Kuiper Belt Objects with the greatest distance from the Sun (of those that are known of by humans) revolve “around the Sun in patterns most readily explained by the presence of a hypothetical ‘Planet Nine’ approximately 10 times the mass of Earth.”
That would be something to see wouldn’t it?
A press release on the subject provides more: “According to the researchers’ calculations, such a hypothetical planet would complete one orbit around the Sun roughly every 17,000 years and, at its farthest point from our central star, it would swing out more than 660 astronomical units, with one AU being the average distance between Earth and the Sun.”
To provide more of a handle on the methods used by the researchers — current theory (largely backed by observation) is that objects in the Kuiper Belt are heavily influenced by the movements of Saturn, Uranus, Neptune, and Jupiter, whether directly or indirectly.
The Kuiper Belt, for those that aren’t familiar with the term, is an enormous region beyond the orbit of Neptune where vast numbers of dwarf planets, comets, meteors, and spheres of ice, dust, and rocks, orbit.
The press release continues: “However, there are a few known Kuiper Belt objects (KBOs) that are unlikely to be significantly perturbed by the known giant planets in their current orbits. Referred to as ‘extreme KBOs’ (eKBOs) by the authors, all of these have extremely large orbital eccentricities, in other words, they get very close to the Sun at one point on their orbital journey, only to swing far out into space once they pass the Sun, on long elliptical orbits that take these strange mini worlds hundreds of AUs away from the Sun.”
“We analyzed the data of these most distant Kuiper Belt objects,” commented Renu Malhotra, a Regents’ Professor of Planetary Sciences in the UA’s Lunar and Planetary Lab “and noticed something peculiar, suggesting they were in some kind of resonances with an unseen planet.”
What the researchers found was that “the orbital period ratios of these objects are close to ratios of small whole numbers. An example of this would be one KBO traveling around the Sun once while another takes twice as long, or three times as long, or four times as long etc, but not, say, 2.7 times as long. According to the authors, such ratios could arise most naturally if the extreme KBOs’ orbital periods are in small whole number ratios with a massive planet, which would help to stabilize the highly elliptical orbits of eKBOs.”
These findings corroborate earlier ones from other research teams that found that 6 of these bodies move on “highly eccentric orbits whose long axes all point in the same direction. This clustering of orbital parameters of the most distant KBOs suggested a large, planetary size body shepherding their orbits.”
The researcher’s calculations also lead to 2 likely orbital planes for the ninth planet, if it exists — one relatively near the mean plane of the solar system, and also near the mean plane of the 4 eKBOs (~18°); and one heavily inclined, at around 48°.
As you can probably guess, the researchers stressed involved in the new work have stressed that there it isn’t definitive proof of a ninth planet, but simply an exploration of the subject/theory. Much remains unknown about the objects that orbit in the far reaches of the solar system.
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