Astronomy Picture of the Day . Orcus of the Outer Solar System . ... Credit: M. Brown ( Caltech ), C. Trujillo ( Gemini ), D. Rabinowitz ( Yale ), Samuel Oschin Telescope Explanation: A newly discovered object in the outer Solar System moves like an anti-Pluto. 90482 Orcus was first discovered in 2004 and is slightly smaller than Pluto , although still one of the largest Kuiper belt objects known. ... Publications with words: kuiper belt . ... Solar System Object Larger than Pluto Discovered . ...