(55637) 2002 UX25




(55637) 2002 UX25 is a possible dwarf planet that orbits the Sun in the Kuiper belt beyond Neptune. Its orbit takes roughly 280 years, and it has one known moon. This moon makes it much easier to calculate mass, and when the size is known, also a density. The low density of about 0.82 g/cm3 has been a surprise to astronomers.<ref name=cowen>Ron Cowen - Nature - Astronomers surprised by large space rock less dense than water Kuiper belt object challenges planet-formation theories. (13 November 2013)</ref>

It is a trans-Neptunian object with an absolute magnitude of 3.9,<ref name="jpldata" /> making it highly likely to be a dwarf planet. The Spitzer Space Telescope results estimate it to be about 681 km in diameter.<ref name="spitzer" /> It was discovered on 30 October 2002, by the Spacewatch program.<ref name="MPEC2002-V08" /> It is a mid-sized cubewano similar in size to 20000 Varuna.

(55637) 2002 UX₂₅ sections