Cosmosera

Cosmosera is a fictional exoplanet used in educational materials and science fiction to illustrate planetary habitability and rocky-planet geology. It functions as a stand‑in for real-world exoplanets in discussions of planetary structure, atmospheres, and climate. The name combines the word cosmos with a common planetary-nomenclature suffix.

In the canonical description, Cosmosera orbits a sun‑like star at roughly 0.9 astronomical units, placing it in the habitable zone. The planet’s radius is about 1.3 times that of Earth and its mass around 2.5 Earth masses, implying a predominantly rocky interior with a substantial water component. Its modeled atmosphere is nitrogen–oxygen with trace carbon dioxide, supporting liquid water under moderate surface pressures.

Its surface is described as ocean‑dominated, with continental regions that influence climate and tectonics. Geological evidence in the canon suggests active plate tectonics and a magnetic field. The climate is moderated by oceans, yielding mild average temperatures and seasonal variability. Possible biosignatures include atmospheric redox disequilibria and other gas combinations compatible with life in a water‑rich world.

Exploration in fiction and pedagogy often imagines future telescopic observations to detect atmospheric constituents, surface composition, and potential biosignatures. Cosmosera is used to discuss questions of habitability, observational limits, and ethical considerations surrounding planetary engineering and colonization in speculative scenarios.