Read more of this story at Slashdot.
It's one of the most intriguing questions about the Solar System from the last five years: Is there a large planet, lurking out in the cold dark reaches, on an orbit so wide it could take 20,000 years to complete? The answer has proven elusive, but a new study reveals what could be traces of the mysterious hypothetical object's existence. From a report: Astronomer Michael Rowan-Robinson of Imperial College London in the UK conducted an analysis of data collected by the Infrared Astronomical Satellite (IRAS) in 1983, and found a trio of point sources that just might be Planet Nine. This, Rowan-Robinson concludes in his preprint paper, is actually fairly unlikely to be a real detection, but the possibility does mean that it could be used to model where the planet might be now in order to conduct a more targeted search, in the quest to confirm or rule out its existence. "Given the poor quality of the IRAS detections, at the very limit of the survey, and in a very difficult part of the sky for far infrared detections, the probability of the candidate being real is not overwhelming," he wrote. "However, given the great interest of the Planet 9 hypothesis, it would be worthwhile to check whether an object with the proposed parameters and in the region of sky proposed, is inconsistent with the planetary ephemerides." Speculation about the existence of a hidden planet in the outer reaches of the Solar System has swirled for decades, but it reached a new pitch in 2016 with the publication of a paper proposing new evidence. Astronomers Mike Brown and Konstantin Batygin of Caltech found that small objects in the outer Solar System's Kuiper Belt were orbiting oddly, as though pushed into a pattern under the gravitational influence of something large. But finding the dratted thing is a lot more complicated than it might sound. If it is out there, it could be five to 10 times the mass of Earth, orbiting at a distance somewhere between 400 and 800 astronomical units (an astronomical unit is the average distance between Earth and the Sun; Pluto, for context, is around 40 astronomical units from the Sun). This object is very far away, and quite small and cold and probably not reflecting much sunlight at all; and, moreover, we don't know exactly where in the very large sky it is. So the jury is out on whether it is real or not, and the topic is one of pretty intense and interesting debate. IRAS operated for 10 months from January 1983, taking a far-infrared survey of 96 percent of the sky. In this wavelength, small, cool objects like Planet Nine might be detectable, so Rowan-Robinson decided to re-analyze the data using parameters consistent with Planet Nine.