Ceti Alpha VI

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 to 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, Chekov realized that they were mistaken. (Star Trek II: The Wrath of Khan)