Písluný

Písluné is a term used in speculative fiction and worldbuilding to describe a luminous atmospheric phenomenon associated with a gas giant in a fictional star system. It denotes a broad, halo-like arc that encircles the planet's equator and is visible from the planet's moons or from space.

The phenomenon is described as photochemically produced by ultraviolet radiation from the parent star interacting with complex hydrocarbons in the upper atmosphere, forming a diffuse, glowing haze that refracts light. Colors are typically reported as pale blue to emerald, with brightness that can vary according to the planet’s seasons, atmospheric composition, and solar activity.

Observation and interpretation vary across their fictional settings. In many narratives, písluné serves as a navigational marker for interplanetary travelers and as a cultural symbol that influences calendars, mythologies, and storytelling. The feature may appear as a continuous halo or as distinct elements such as arcs or veils, depending on atmospheric dynamics described in the world.

Etymology and usage: the name písluné is a constructed term without a real-world linguistic lineage, chosen to convey a sense of light and lunar association within the fictional framework. In published worldbuilding resources, it is often categorized under atmospheric optics and planetary phenomenology, alongside other imagined phenomena.

See also: aurora, zodiacal light, atmospheric optics, planetary science, worldbuilding concepts.