Earthin

Earthin is a fictional planet that appears in science fiction narratives as an Earth analogue. In many depictions it shares a familiar solar neighborhood and a breathable atmosphere, while exhibiting variations that invite exploration of alternate histories, ecologies, or technologies. The planet is usually described as roughly Earth-sized, with a radius near 0.95 to 1.15 times that of Earth and a similar bulk density, giving surface gravity close to 0.9 to 1.1 g. Its orbit around a sun-like star often places it in the habitable zone, and rotation periods range from about 20 to 30 hours, producing days shorter or longer than Earth’s.

The atmosphere is typically nitrogen-oxygen dominated, but some versions feature different compositions, higher or lower greenhouse effects, or episodic air quality issues that affect climate and habitability. Oceans are common, covering a comparable fraction of the surface and driving weather patterns that resemble Earth’s, yet regional climates may diverge due to altered land distribution or ocean currents.

Geography on Earthin is variable across works: continents may resemble Earth’s or be reorganized to produce distinct biomes and climate belts. Life is often terrestrial and aquatic, with ecosystems ranging from forests to deserts; some narratives also introduce indigenous intelligent species or human settlements.

As a storytelling device, Earthin provides a familiar framework for examining environmental stewardship, geopolitics, colonization, and the social implications of technological change, while remaining distinct enough to explore speculative ideas.