The Mt. Polomar Facility has found a planet found a planet that can be smaller then pluto and threee times further away than pluto. yet still orbits
the sun. I never Heard of it until today but it sounds true.
Sedna is one of many 'Transneptunian' or 'Kuiper Belt Objects' known to orbit the sun beyond Neptune. Pluto, and Eris (which is larger than
Pluto) are now both classified as 'dwarf planets'.
This wikipedia page looks to be fairly accurate so far as I can tell. As you can see, Sedna is one of a number of candidates to be classified as a
'dwarf planet'.