Lexos

Lexos is a fictional planet featured in the science fiction novel "Project Hail Mary" by Andy Weir. It is the homeworld of the Eridians, an alien species. The planet is described as having a dim, red sun and a nitrogen-oxygen atmosphere. Lexos is characterized by its extremely high gravity, which has significantly influenced the evolution and physiology of its inhabitants. Eridians are adapted to this intense gravitational pull, possessing dense bones and a compact, robust build.

The planet's environment is harsh, with extreme temperature fluctuations and a lack of readily available water on the surface. Much of the Eridian civilization is subterranean or located in shielded habitats to cope with the planetary conditions. Lexos plays a crucial role in the narrative as the source of an organism, Astrophage, which poses a threat to Earth's sun. The Eridians, facing their own existential crisis due to Astrophage, are the key to discovering a solution that can save both their planet and Earth. Their advanced scientific knowledge and their unique biological adaptations are central to the plot's resolution.