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Will Planet Nine Emerge from Hiding Soon?
Few science stories rise to the occasion of occasioning push notifications from both the New York Times and NPR. Planet Nine was among a handful of recent examples.
In mid-January of 2016, two Caltech Professors -- Konstantin Batygin and Mike Brown -- kicked the news media into high gear by predicting the existence of a new, but as-yet unseen, planet in the outer solar system. They asserted that Neptune et al.'s erstwhile sibling has an orbital period of about 20,000 years, and a super-Earth mass more than sufficient to bring the planet count back up to nine.
Batygin and Brown's paper, despite containing a bracing dose of secular perturbation theory, has been downloaded over 300,000 times, and presents indirect dynamical evidence for Planet Nine. Its presence is inferred through the gravitational sculpting that it has produced in the trajectories of the most distant Pluto-like worlds that lie beyond Neptune's orbit.
Based on the host of recent results, Metaculus now calculates a most probable current sky position for Planet Nine of RA=2h, Dec=0 deg. This area of the sky is currently close to optimal visibility for a planet at opposition. At the most probable location, the planet's current distance would be r~600 AU, and the expected V magnitude is 21. A number of groups have engaged in the hunt, and there is something of an emerging consensus that if the planet is to be found, it'll be found sooner rather than later. As an example, Mike Brown gives sixteen months. This second update to our original, now closed, Planet Nine question is thus in order:
Will the discovery by direct observation of a new solar system planet having characteristics substantially similar to those described in the Batygin-Brown paper, be announced in a peer-reviewed paper prior to the Jan. 20, 2017 first anniversary of the Batygin-Brown prediction?
(For this question to resolve as "Yes", the new solar system planet should have an inferred radius larger than that of Earth, an orbital period greater than 5,000 years, and an orbital eccentricity e > 0.25).
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