A majority of dwarf planets lie tucked away in the depths of our solar system.
The world, 2007 OR10, is much larger than astronomers previously thought, making it the third largest dwarf planet on a list of half a dozen worlds.
Many dwarf planets are hard to detect because they look like tiny points of light. That was one of the challenges of finding 2007 OR10.
Our revised larger size for 2007 OR10 makes it increasingly likely the planet is covered in volatile ices of methane, carbon monoxide and nitrogen, which would be easily lost to space by a smaller object.
One observation scientists have made is that 2007 OR10 is a very dark world, which could give us clues about the early history of our solar system
"We think this object is left over from when our sun and solar system first formed," NASA scientist Geert Barentsen said. "It's almost as old as the sun itself."