Pirdia XI is the farthest moon of a large gas giant Pirdia, which is situated in the Tyrius system of the Savareen sector. It has been called the smallest moon in the whole galaxy and with no atmosphere and a rocky surface, it is generally uninhabitable.

Due to its size, Pirdia has a strong gravitational field. However, the distance and orbit of Pirdia XI suggest that the pull between the gas giant and its moon is tenuous at best. Some scientists believe that this is due to Pirdia XI's small size, which is equal to many asteroids. It has also been hypothesized that the tiny moon was once an "independent" planet, which was caught in the gravitational field of Pirdia, but never strongly bound to it.