Ceti Alpha VI
Ceti Alpha VI was the uninhabited sixth planet of the Ceti Alpha system. This system was located in Sector 25712 of the Alpha Quadrant. It was located a considerable distance from the Delphic Expanse and the planet Denobula as well as three days away from Regula I at an unspecified warp speed. The nearest starbase was Starbase 12. (; ; )

The planet exploded for reasons unknown in 2267, approximately six months after Khan Noonien Singh and his followers were exiled on Ceti Alpha V. The shock of the explosion shifted the orbit of Ceti Alpha V, destroying that planet's ecosystem, making the planet virtually uninhabitable. 

In 2285, the  arrived in the Ceti Alpha system to find a suitable planet for testing of the Genesis Device. Pavel Chekov and Captain Clark Terrell beamed down to Ceti Alpha V, mistakenly thinking it was Ceti Alpha VI. Just before they were captured by Khan and his Augments, Chekov realized that they had made a grave error, discovering that the cargo containers they'd found belonged to Khan's ship, the Botany Bay. ()

In an alternate timeline, Human refugees fled to the Ceti Alpha system, following the Xindi's successful destruction of Earth in February 2154, during the relentless pursuit of the Xindi to eradicate all Human colonies. ()

Appendices

Background information 

This planet's quadrant of origin is inferred based on the position of Starbase 12, the closest starbase, as seen in the star chart appearing in the  episode .

Apocrypha 
In Greg Coxs  To Reign in Hell: The Exile of Khan Noonien Singh, Spock theorizes that a small black hole might have passed through the system, too small to be detected easily by the sensors aboard the , and that its immense gravity destroyed Ceti Alpha VI and fundamentally altered the orbit of Ceti Alpha V.

The Star Trek: Vanguard novel Storming Heaven sets out that its destruction is inadvertently caused by Starfleet use of  technology.

External link 
    

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Ceti Alpha 06