This is an artist's view of a Kuiper Belt binary object, called 1998 WW31. These icy bodies orbit each other at the fringe of our solar system. The illustration depicts one member of the duo in the foreground; its companion - the dark, round object - is in the background. The objects are about the same size. Both are illuminated from behind by the Sun [the white dot at upper left]. Like other Kuiper Belt objects, this duo orbits the Sun, completing a circuit every 301 years. The planet Pluto orbits the Sun every 248 years.

Credit: NASA/ESA and G. Bacon ( Space Telescope Science Institute)