The Solar System just got a lot more far-flung. Astronomers have discovered1 a probable dwarf planet that orbits the Sun far beyond Pluto, in the most distant trajectory known.

Together with Sedna, a similar extreme object discovered a decade ago2, the find is reshaping ideas about how the Solar System came to be. “It goes to show that there’s something we don’t know about our Solar System, and it’s something important,” says co-discoverer Chad Trujillo, an astronomer at Gemini Observatory in Hilo, Hawaii. “We’re starting to get a taste of what’s out beyond what we consider the edge.”

Trujillo and Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington DC, report the finding today in Nature.

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