Ceti Alpha VI was the sixth planet in the Ceti Alpha system. The planet exploded some time around 2267, approximately six months after Khan Noonien Singh and his followers were stranded on Ceti Alpha V. The shock of the planet's explosion shifted the orbit of Ceti Alpha V and laid most of the planet waste. In 2285, the USS Reliant arrived in the Ceti Alpha system to find a suitable planet for the Genesis Device. Pavel Chekov and Captain Clark Terrell beamed down to Ceti Alpha V, thinking it was Ceti Alpha VI. When they were captured by Khan and his augments, Khan realized that they were mistaken. (Star Trek II: The Wrath of Khan)
- It was not revealed in the story what forces were at play to cause an entire planet to destroy itself, or possibly be destroyed by external forces. It was also not revealed whether the explosion was a spontaneous reaction or some other type of long-term build-up.