From Halopedia, the Halo wiki
Cygnus was one of two habitable worlds in the system colonized by the Unified Earth Government, the other being New Jerusalem. Chyler Silva of the Silva family was born on Cygnus before moving to Mamore.
In 2550, a colony ship traveling to Cygnus suffered a catastrophic slipspace malfunction due to its improperly mounted slipspace drive. When the drive was activated, the ship was cut in half and 700 crew and passengers were killed.
List of appearances