Pluto

Pluto is a dwarf planet (previously classified as a planet) in the Sol system. It lies between Neptune and Eris. It is the same classification as Ceres and Eris.

The planet which was also known as Sol IX became Humanity's new home after Earth's resources were exhausted. These remaining Humans were shipped to Pluto by the Usurians, and 6 artificial suns were placed around Pluto. (DW: The Sun Makers)