Varnex was one of two moons of planet Mestiko, along with Kifau. Sometime prior to 2265, a permanent research base had been established on Varnex, with a staff of thirty-four. When a rogue pulsar passed through the Mestiko system, the Starship Enterprise was able to evacuate the entire base, despite being unable to prevent massive damage to the planet. The pulsar also had the effect of pulling Varnex into a more elliptical orbit around Mestiko (and tearing Kifau from its orbit altogether). (TOS eBooks: Mere Anarchy: Things Fall Apart, The Darkness Drops Again)
In 2283, Dr. Theena elMadej proposed the establishment of the Discovery Center on the site of the lunar base on Varnex, as a facility where the Payav and others could dedicate themselves to pure scientific research. (TOS eBook: Mere Anarchy: The Blood-Dimmed Tide)
- The name of the moon was not revealed until The Darkness Drops Again.