Pluto

Description
Pluto is one of Sol's numerous "ice dwarf" worlds. It is mainly of note for being the gravitational "anchor" for the Mass Relay to Arcturus. Pluto and the Charon Relay (formerly encased in ice, and considered a moon) orbit each other. Pluto's orbit was circularized in 2157 as a side effect of the Charon Mass Relay recovery operations.

Population (gateway stations): 9300

Trivia

 * Mass Effect was completed somewhat before Pluto's "demotion" to dwarf planet status. The game therefore treats Pluto as the ninth planet. It is not presently known whether the Mass Effect canon will continue to treat Pluto as a full planet or reflect its demotion.
 * While in actuality Pluto has three satellites, this is not the case in Mass Effect, as Charon, the largest moon of Pluto, is revealed to be a Mass Relay that has been encased in ice.