Ettra

Ettra 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. Ettra is described as a tidally locked world, meaning one side perpetually faces its star, while the other is in eternal darkness. This extreme condition has shaped the evolution and society of the Moties.

The star that Ettra orbits is designated as the "Mote." Due to the planet's tidal locking, Ettra experiences extreme temperature gradients. The starward side is scorching hot, while the dark side is frigid. The habitable zone for the Moties is a twilight band between these two extremes. This unique environment has led to a complex and resource-intensive civilization, as the Moties must manage and channel energy across their world. Their technology is highly advanced, particularly in areas related to environmental control and resource management, driven by the necessity of survival on Ettra. The challenges of their homeworld have also significantly influenced their biology and social structure, fostering a highly communal and organized society.