Martian Federacy
Federacy.  It is home to eight planets, numerous dwarf planets, and a myriad of
smaller celestial bodies.  Mars is the only inhabited planet, being the very first
planet terraformed.  Seven of the moons in the system have been terraformed
(four Jovian, one Saturnian, and one Neptunian.  

The system is also home to two megacorporations.