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Efros, also known as Efros Delta, is the fourth planet in the Flarset system and homeworld of the humanoid Efrosians, a member of the United Federation of Planets.


See Efrosians.

The planet Efros was in the throes of an ice age as recently as the mid-13th century. In fact, the very name "Efros" translates as "ice" in the Efrosian language.


The United Federation of Planets made first contact with Efros in 2278 when the USS Surak visited the planet.

A notable citizen of Efros is Federation President Ra-ghoratreii. (TOS movie: Star Trek VI: The Undiscovered Country; ST novel: Articles of the Federation; TTN novel: Taking Wing)

Planetary Information


Efros is a cold world with virtually no variety in climate and massive glaciers dot the landscape. However, the planet does have an abundant supply of metals and geothermal energy. Most of the Efrosian people live in the small temperate zone aound the equator.

Natural History

The cold, harsh conditions on Efros make it difficult for animals and plants to thrive, but some native non-intelligent organisms do exist.