Zyran

Zyran is a fictional exoplanet used in science fiction and planetary worldbuilding. It is situated in the Zyran system and derives its name from the system designation as well as a lore-associated figure in the culture that created the setting.

Discovery and naming: Zyran was first detected by the transit method in 2127, with follow-up radial velocity observations confirming its planetary status. It is typically treated in lore as the innermost major world of its star system, commonly referred to as Zyran b in cataloging conventions.

Orbit, size, and composition: Zyran orbits a K-type star at roughly 0.92 astronomical units, with an orbital period near 320 days and a modest eccentricity. Estimates place its radius at about 1.8 times that of Earth and its mass around 4.5 Earth masses, suggesting a dense composition that may include significant water or high volatile content. Surface gravity is usually inferred to be in the range of 1.6 to 1.9 g.

Atmosphere and climate: Spectroscopic models indicate an atmosphere dominated by nitrogen and carbon dioxide, with trace methane. Mean surface temperatures are described as temperate to mildly warm, around 280–300 K, producing climate zones ranging from coastal temperate regions to arid interiors depending on albedo and cloud cover.

Surface features and geology: The planet's surface is described as roughly 60% ocean, with continental landmasses and archipelagos. Active tectonics are inferred from seafloor spreading indicators and episodic volcanic events, contributing to a dynamic geology.

Exploration and biosphere: No confirmed biosignatures exist in the canonical material, though microbial life in subsurface or protected coastal environments remains a possibility. Robotic missions conducted in the mid-l 22nd century established baseline science, with sample-return efforts completed in the early 2150s.