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fork(2) [soylentnews.org] writes:

      Science News [sciencenews.org] describes more evidenc and clues about where to search for a possible ninth planet lurking in the fringes of our solar system.

      From the article:

Evidence for the existence of Planet Nine is scant, based on apparent alignments among the orbits of the six most distant denizens of the Kuiper belt (SN: 2/20/16, p. 6 [sciencenews.org]). Their oval orbits all point in roughly the same direction and lie in about the same plane, suggesting that a hidden planet, about five to 20 times as massive as Earth, has herded them onto similar trajectories.

Planetary scientists Mike Brown and Konstantin Batygin, both at Caltech, announced this evidence in January. Now they've used it to refine Planet Nine's properties and narrow in on where it might be hiding. Their results appear in the June 20 [issue of] Astrophysical Journal Letters [iop.org].

Planet Nine's average distance from the sun is most likely between 500 and 600 times as far as Earth's, Brown and Batygin report. Its orbit is highly stretched and tipped by about 30 degrees relative to the rest of the solar system, taking it well above and below the orbits of the eight known worlds. And right now, it's probably near its farthest point from the sun -- possibly as far as 250 billion kilometers away -- in a large patch of sky around the constellation Orion.

But the evidence depends on orbital oddities among just six frozen worlds. "The argument that a planet is there is not ironclad," cautions Renu Malhotra, a planetary scientist at the University of Arizona in Tucson. "I think it's worth studying. There's enough there to not ignore this evidence," she adds. "We just shouldn't get depressed if the planet's not there."

Malhotra and colleagues have been looking for independent evidence for a ninth planet. And they think they've found another clue: The orbital periods of those six bodies [iop.org] are roughly synced to one another, her team reports in the same journal.

[...]

A planet at least 10 times as massive as Earth and orbiting the sun once every 17,117 years would be in sync with four of these bodies, Malhotra and colleagues find. That puts Planet Nine, on average, about 100 billion kilometers from the sun, or roughly 665 times the distance between the sun and Earth.

[...]

"The real problem is knowing where to look," [Jonathan Fortney, a planetary scientist at the University of California, Santa Cruz] says.

Brown and Batygin think they've narrowed it down to roughly 2,000 square degrees of sky near Orion. "That's not as horrific as you might imagine," Batygin says. The Subaru telescope in Hawaii, which is large enough to detect Planet Nine, could cover that swath in about 20 nights, he says.

      (Remember when Pluto [wikipedia.org] was the ninth planet? Not anymore, man!)

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