Eetris

Eetris is a fictional planet featured in the science fiction novel "The Mote in God's Eye" by Larry Niven and Jerry Pournelle. It is the homeworld of the Moties, an alien species encountered by humanity. Eetris is described as a tidally locked world orbiting a red dwarf star, resulting in extreme environmental conditions. One side of the planet experiences perpetual daylight and intense heat, while the other is in constant darkness and frigid cold. The Moties inhabit a narrow habitable zone between these extremes, known as the terminator.

The planet's geology is characterized by volcanic activity and a thin, toxic atmosphere. Resources are scarce, which has profoundly shaped the Motie civilization and their evolutionary path. Their biology is adapted to this harsh environment, leading to a complex social structure and advanced technology, particularly in areas related to survival and resource management. Eetris's unique conditions are a central element in the plot of "The Mote in God's Eye," influencing the interactions and conflicts between humans and the Moties. The novel explores how the environment of Eetris has driven the Moties' biological and societal development, making them a formidable and intriguing alien race.