Khitomer

Gagarin IV – Location of the Federations' Darwin Genetic Research Station. Possibly named after Yuri Gagarin, the first Human in space in 1961.

Gaia – Gamma Quadrant Class-M planet surrounded with a strange quantum energy barrier. In the 22nd Century, the planet was colonized by the crew of the USS Defiant who were sent back into an alternate timeline when the Defiant crashed on the planet and could not send a distress call.

Galador II – A Galador freighter is described as traveling between Farius Prime and Galador II in DS9 episode "The Maquis."

Galdonterre – Planet where the alien known as "The Albino" hid after enacting his revenge against the Klingon's Kang, Kor, and Koloth.

Galen IV – Planet contested between the Federation and the Talarians. It is the birthplace of Jeremiah Rossa/Jono.

Gallos II – Planet with a ruling family named Tanagra.

Galor IV – Location of the Daystrom Institute.

Galorda Prime – Planet where in 2370, a Klingon transport crashed.

Galorndon Core – A magnetically unstable planet near the Romulan Neutral Zone. In 2366 Lt. Cmdr. La Forge is trapped on the planet with a Romulan survivor of a crashed shuttle named Centurion Bochra. The electromagnetic storms blinded Geordi's VISOR and paralyzed the Romulan's nervous system, and the two had to work together to survive. The planet was a rendezvous point for the delivery of a stolen deflector array; The Romulan commander Chulak was defeated here.

Galvin V – Planet indicated by Data as having inhabitants who only consider a marriage successful if the couple has a child within the first year.

Gamelan V – Planet threatened by a space barge that leaked radioactive waste into the atmosphere.

Gamma 400 – System where Starbase 12 is located. It lies near the Mutara Nebula.

Gamma II – An uninhabited planetoid where an un-manned Federation research station is located. It was visited by the USS Enterprise

Gamma VII-A – A system around a fourth magnitude sun with billions of inhabitants, killed by a giant space amoeba.

Gamma Canaris IV – Planet Commander Kieran MacDuff (a disguised Satarran) claimed he was from.

Gamma Canaris N – Planet where the developer of Warp technology, Zefram Cochrane, survived alone for many years.

Gamma Hromi II – Planet in the Hromi Cluster where a group of Acamarian Gatherers planned an ambush of Federation personnel.

Gamma Hydra II – Captain Kirk, under the effects of rapid aging, mistakes Gamma Hydra IV for Gamma Hydra II.

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Wikipedia