The crossword solution for the term PLUTO, TO SATURN is SON. Pluto is a dwarf planet located in the Kuiper belt, beyond Neptune. It is the ninth-most-massive body observed directly orbiting the Sun and the second-most-massive known dwarf planet in the Solar System. Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. Pluto is the SON of Saturn in terms of its location in the Solar System.