XVIIlea

XVIIlea is a fictional exoplanet in the Terra Synthesis science fiction setting. It is described as a rocky terrestrial world in the habitable zone of a K-type star, about 20 light-years from Earth. The planet is characterized by broad, level plains of grassland, interspersed with tall basalt formations and scattered alpine plateaus, yielding a stark but varied landscape.

Name and discovery: The name combines XVII, the seventeenth target in the series’ survey nomenclature, with lea, an Old English term for meadow, chosen to reflect the expansive plains described by early explorers. In-universe surveys began with orbital reconnaissance and progressed to surface expeditions during the Asterion era of Terra Synthesis publications.

Physical characteristics: Estimates place XVIIlea at roughly 1.1–1.2 Earth radii with a mass near 0.9–1.0 Earth masses, yielding surface gravity close to 0.95 g. The orbital period around its star is about 72 days. The atmosphere is nitrogen-rich with trace carbon dioxide, producing a surface pressure around 0.7 atmospheres and a relatively thin air column.

Geography and archaeology: The plains are cut by escarpments and basalt columns. Seasonal winds drive dust storms that influence erosion and sedimentation. The XVIIlea Ruins, an extensive network of arches, carved panels, and kiln-baked bricks, are the major archaeological feature and have yielded inscriptions that inform models of the planet’s late prehistory. No confirmed macroscopic native life has been documented on the surface.

In fiction, XVIIlea is used as a setting to explore themes of climate change, ancient migration, and the coevolution of human and planetary histories. It appears in several Terra Synthesis works, including the novels The Cartographer’s Atlas and the video game Echos of the Plains.