Giant ninth planet?

A MONSTER may be lurking in our solar system. The strange orbit of a newly discovered dwarf planet hints at a giant, unseen rocky world, 10 times bigger than Earth and orbiting far beyond Pluto. The dwarf planet, dubbed 2012 VP113, is an interesting discovery in itself, as it is now the most distant known body in our solar system. At its closest approach, it is 80 astronomical units from the sun (1 AU is Earth’s distance), says Scott Sheppard of the Carnegie Institution for Science in Washington DC, who led the team that discovered it (Nature, DOI: 10.1038/nature13156). That’s twice as far as the most famous dwarf planet, Pluto. The previous record holder was Sedna, at 76 AU out. But Sheppard’s team also report that the orbits of 2012 VP113, Sedna and 10 other objects are strangely aligned. One explanation could be the tug of a rocky planet that is 10 times the size of Earth and orbits the sun at 250 AU. Although a NASA telescope has already scoured for distant planets without success, it could only detect the warmth of gas giants – a rocky planet is colder. But there are other ways to explain the orbits, including the pull of stars or “rogue” planets kicked out of our solar system.