Big Trans-Neptunian Object(TNO), 2003 EL61, found beyond Pluto in the Edgeworth-Kuiper belt. It´s either a bright asteroid/huge comet - these denizens of the solar system´s edge are difficult things to describe in a way that wouldn´t create wrong impressions - or possibly a planet bigger than Pluto itself, if it´s dim enough. Some objects found from the Edgeworth-Kuiper belt have been previously thought to be bigger than they really are, because they have been found out to be brighter than expected.