The Cerullean Sector (also known as Celeste Sector ) was a the sector of the Polaris Galaxy, located west of the Zarkov Sector and the Verdigris Sector and southwest of Praxus Sector.
It was where Ratchet and Clank first crash landed onto Cobalia and met Talwyn, Cronk, and Zephyr.The duo crash landed on Cobalia and met The Smuggler, who gave them a flight to Kortog, only to eject them through the cargo hold. On Kortog, in the Hall of Knowledge, Ratchet and Clank got the coordinates to Fastoon. On Fastoon, they found an old Lombax ship named Aphelion. She became their ship for the rest of the game. Qwark sent them an invite to Mukow for the Imperial Fight Festival, where they won the Heli-Pod. On the Nundac Asteroid Ring, they met Talwyn, Cronk, and Zephyr, who joined the duo for the rest of the series. On Ardolis, Ratchet and Clank stole an artifact, that belonged to Talwyn's father, from the Space Pirates. Later, at the end of the game, on Fastoon, Ratchet, Clank, Talwyn, Cronk, and Zephyr fought through Tachyon's forces and leared the true fate of the Lombaxes.
During Ratchet & Clank: Into the Nexus, the Nebulox Seven Prison Ship was transporting Vendra Prog to the Vartax Detention Center by passing through this sector but was eventually destroyed by the Thugs-4-Less and killing Cronk and Zephyr in the process. Later, according to Talwyn, Mr. Eye destroyed a few of the Polaris Defense Force outposts in this sector after being released by Vendra Prog.
- The Cerullean Centipede and Cerullean Swarmer were named after the sector they originated in. Surprisingly however, they were also seen outside the Cerullean Sector, especially in Jasindu.
- This was the home sector of the Lombaxes due to Fastoon being in the Cerullean Sector.
- Angela Cross was last seen in the Cerullean Sector.
- 'Cerullean' is quite similar to 'Cerulean', which is another name for blue.