Is ‘Planet Nine’ a zero?
The hunt for Planet Nine—an as-yet-unseen ninth planet lurking somewhere in the outer reaches of our solar system—has consumed astronomers since its existence was first hypothesized in 2016. But new research suggests that this mysterious object might not exist, reports Astronomy.com. Planet Nine believers think that only a single, massive world could explain the strange orbits of many small icy and rocky objects in the Kuiper Belt, a doughnut-shaped region beyond Neptune. Antranik Sefilian, from the University of Cambridge, said he found that theory “fascinating” but wanted to see “whether there could be another less dramatic and perhaps more natural cause for the unusual orbits.” He and his team ran computer models to see what other celestial bodies might have a gravitational pull similar to Planet Nine’s. They determined that an enormous disk of icy debris—with a mass up to 10 times that of Earth—would do the trick. Sefilian is confident his “shepherding disk hypothesis” is feasible. But he acknowledges that, as with Planet Nine, there’s no evidence for the disk’s existence.