Some scientists believe that a huge planet which has never been seen by astronomers could be lurking, almost invisibly, at the dark edges of our solar system.
But the idea of ‘Planet Nine’ might be wrong – and instead, there might be another mysterious object out there – a spinning disc of icy bodies, 10 times the mass of Earth, a new study has suggested.
Beyond the orbit of Neptune lies the Kuiper Belt, which is made up of small bodies left over from the formation of the solar system.
Some of the rocks out there – trans-Neptunian Objects (TNOs) – have distinctly odd orbits, which has led some scientists to believe there’s a planet out there.
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But the new study used computer modelling to suggest that there might be a huge disc of icy objects out there instead.
Study author Antranik Sefilian, a PhD student at Cambridge said, ‘The Planet Nine hypothesis is a fascinating one, but if the hypothesized ninth planet exists, it has so far avoided detection.
‘We wanted to see whether there could be another, less dramatic and perhaps more natural, cause for the unusual orbits we see in some TNOs.
‘We thought, rather than allowing for a ninth planet, and then worry about its formation and unusual orbit, why not simply account for the gravity of small objects constituting a disk beyond the orbit of Neptune and see what it does for us?’
‘If you remove planet nine from the model, and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs.’