Scooping up an atmosphere
Interesting hypothesus. (registration required)
Prentice believes gases released from Titan's interior formed its air. Others, including Ross Taylor from the Australian National University, suspect Titan's atmosphere may not be its own.
Titan's neighbouring moon, Hyperion, suffers from a tumbling, chaotic rotation, the result of a long-ago cataclysmic collision with a comet or asteroid. Titan's gravity may have scooped up the debris - a readymade atmosphere.
Terraformers take note!