![\"Hypothesised](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/05\/SEI_253653853-0611.jpg\")
\n\t\tPlanet Nine, also called Planet X, has never been caught on a telescope (Picture: Getty Images\/Science Photo Libra)<\/p>\n
\t\t
\n\t\tPlanet Nine, also called Planet X, has never been caught on a telescope (Picture: Getty Images\/Science Photo Libra)<\/p>\n
Scientists hunting for Planet Nine, an elusive planetary body<\/a> that could change our understanding of the solar system, have found something.<\/p>\n Planet X is a hypothetical planet seven times the mass of Earth<\/a> tucked just behind Pluto. <\/p>\n Despite possibly being the fifth most massive planet, scientists have never tracked the white whale of astronomy down \u2013 that is, if it even exists. <\/p>\n But a trio of American scientists trying to find the elusive gas giant have discovered a new planet\u2026 of sorts, a dwarf planet called 2017 OF201.<\/p>\n What is 2017 OF201?<\/p>\n \t\t A dwarf planet is an object large enough that its gravity squishes it into a round shape, but not large enough to \u2018clear the neighbourhood\u2019 of other celestial bodies. <\/p>\n According to a study<\/a>, which has not been peer-reviewed, 2017 OF201 is roughly 430 miles across, three times smaller than Pluto<\/a>.<\/p>\n The object is an extreme trans-Neptunian object (eTNO),\u00a0a minor planet that orbits the Sun far beyond Neptune. <\/p>\n So far away, in fact, OF201 would take 25,000 Earth years to complete a solar lap. Its orbit even swings out into the Oort Cloud \u2013 a sphere of icy comets a trillion miles from the Sun.<\/p>\n OF201 can only be observed from Earth 0.5% of the time, making its closest approach to us in 1930 and won\u2019t do so again until 26,186.<\/p>\n The International Astronomical Union\u2019s\u00a0Minor Planet Center<\/a>\u00a0added 2017 OF201<\/a> to its database last week. Five other dwarf planets are officially recognised: Pluto, Eris, Ceres\u00a0and two others beyond Neptune, Haumea and Makemake.<\/p>\n What is Planet Nine?<\/p>\n \t\t The search for a ninth planet in our solar system has been going on for a century. <\/p>\n The evidence for it that hunters have long clung to is how six objects \u2013 dwarf planets and icy balls \u2013 have been discovered in the vastly empty outskirts of the solar system. <\/p>\n Bizarrely, they huddle together as they orbit, as if something a gassy behemoth of a planet were shepherding them<\/a>, said Imo Bell, astronomer at the Royal Observatory Greenwich.<\/p>\n They told Metro<\/strong>: \u2018Some astronomers believe that proving the existence of this planet would explain the behaviour of many other eTNOs with highly elliptical orbits clustered on one side of the Sun. <\/p>\n \u2018It\u2019s thought that Planet Nine, with a mass of about five Earths, would explain the confined orbits of these\u00a0eTNOs.\u2019<\/p>\n So why is 2017 OF201 a big deal?<\/p>\n \t\t Sihao Cheng of New Jersey\u2019s Institute for Advanced Study and Princeton University graduate students, Jiaxuan Li and Eritas Yang, discovered 2017 OF201.<\/p>\n They did so by combing through an archive of images of the outskirts of the solar system, taken by the Blanco telescope in Chile, as well as by the Canada-France-Hawaii Telescope in Hawaii.\u00a0 <\/p>\n Over time, they realised that tiny dots in the images were a single dwarf planet-sized rock with a wide and eccentric orbit. <\/p>\n Yang said: \u2018It must have experienced close encounters with a giant planet, causing it to be ejected to a wide orbit.\u2019<\/p>\n Yet the discovery isn\u2019t exactly what the team had hoped for, explained Bell, as it\u2019s not part of the pack of eTNOs that imply Planet Nine exists. <\/p>\n \t\t They said: \u2018The discovery of 2017 OF201 is significant\u00a0because it\u2019s\u00a0found in a region of the Solar System thought to be empty, and it\u2019s presence points to the existence of other similar\u00a0eTNOs\u00a0with orbits that challenge ideas about Planet Nine as they are not clustered in the way that has been seen with other eTNOs.\u2019<\/p>\n Yang\u2019s simulations only considered one proposed orbit of Planet Nine, meaning that the findings don\u2019t disprove the planet\u2019s existence altogether. <\/p>\n Cheng hasn\u2019t lost hope, saying that the existence of 2017 OF201 suggests there \u2018could be\u00a0another hundred or so other objects with similar orbit and size\u2019.<\/p>\n \u2018They are just too far away to be detectable now,\u2019 he added. <\/p>\n Get in touch with our news team by emailing us at webnews@metro.co.uk<\/a>.<\/strong><\/strong><\/strong><\/p>\n For more stories like this, <\/strong>check our news page<\/strong><\/a>.<\/p>\n Arrow Arrow![\"Astronomers](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/05\/SEI_253654476-7f6f.jpg\")
\n\t\tThese tiny dots are of a newly discovered dwarf planet candidate (picture: Dr Sihao Cheng)<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/05\/SEI_253655445-caff.jpg\")
\n\t\tMany objects have been discovered beyond Neptune that act strangely \u2013 and shouldn\u2019t even be there (Picture: Education vector illustration)<\/p>\n![\"Undated](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/05\/AN_89820912-ac37.jpg\")
\n\t\tProving the hidden giant exists has long been the goal of some stargazers (Picture: PA)<\/p>\n![\"An](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/05\/SEI_48646978-f65a.jpg\")
\n\t\tOF201\u2019s orbit doesn\u2019t match the clustering of other trans-Neptunian objects (Picture: NASA)<\/p>\n
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