Medea was a planet that occupied the third orbital position in the 12 822 Equuleus system. It was once inhabited by a human population numbering approximately one billion. The population was extinguished by a virulent pathogen, whose release conincided with an Aurelian invasion. It is not clear which side released the pathogen.

Medea has purplish skies and seas. It had once been lush, but had become dry and cold when its aging sun swelled and cooled. The amount of sunlight that reached its surface was less than half that of a typical Earth-type planet. There were no trees on Medea.

When charted by the Pathfinder Ship Pegasus in the early 72nd Solar Century, Medea's surface was covered with craters from a recent asteroid bombardment. This was a common Aurelian tactic for softening the resistance in worlds they attacked. The Medeans, evidently, put up twenty to thirty years of sustained resistance, ranging from battlefield conflict to the use of nucleonic, sonic extreme, and anti-matter weapons. The use of the pathogen, which extinguished all human and animal life, was the ultimate escalation of the conflict.

There was an alternative postulate that Medea was used as aproving grounds for advanced Aurelian weapons.

Before Pegasus left orbit, they left behind a number of androids, programmed to use the planet to build a unique android civilization; their programming limited their numbers, and forbade them to harm humans or pursue space exploration.

(Book 3: Medea)

Years later, Phil Redfire was disappointed that the androids had failed to develop a unique civilization, and instead had put their energy into rebuilding and imitatinf the prior human civlization.

(Book 11: Charlemagne)