Ossus
the third planet in the Adega system, Ossus was home to the site of an ancient Jedi stronghold and training center thousands of years before the Freedon Nadd Uprisings and the Great Sith War. Many historians believe that the Jedi Order originated on Ossus, but this was only conjecture. The planet's atmosphere was laced with electrical storms, probably resulting from the near-devastation it suffered during the Clone Wars. It orbited each of the stars Adega Prime and Adega Besh in an unusual figure-eight orbit, while the other planets in the system had elliptical orbits around both stars. Following the Freedon Nadd Uprisings on Onderon, Jedi Master Arca planned to send the ancient Sith artifacts recovered from Freedon Nadd's ship there for examination, but Exar Kun was able to retrieve them first. In the chaos surrounding the Great Sith War, Aleema Keto and Crado destroyed the Cron System, located near the Adega System. Ossus was caught in the wave of destruction radiating from the supernova. The Jedi attempted to transport the artifacts and lore from the libraries there, but were only able to take a fraction of the wealth stored there over the millennia. In an attempt to preserve a cache of lightsabers, Master Ood Bnar initiated his lifecycle change, becoming a gnarled old tree with the lightsabers engtangled in his roots. He was nearly destroyed by the radiation from the Cron System. Over the ages, great cities grew out of the planet's rough, irradiated terrain. In modern times, the planet was nearly wiped out during the Clone Wars. The enemies of the Jedi Knights struck there, attempting to destroy the stronghold and root out the Jedi. Although the planet was devastated, the Jedi survived. Later, following the death of Emperor Palpatine's first clone on Byss, Luke Skywalker and Kam Solusar discover the planet's ancient Jedi connection, and were directed there by Master Vodo's holocron just before Sedriss executed Operation Shadow Hand. There, they found the Ysanna tribe and the ancient Jedi Master Ood Bnar. In the wake of the Yuuzhan Vong invasion of the galaxy, Master Skywalker chose to establish a new Jedi training academy on Ossus.