Eidolon

Eidolon is Uclea's moon and the astronomical basis of the ten-eidol lunar calendar. Its observed phase cycle lasts exactly thirty-six sols, allowing ten cycles to fit into the 360-sol year.

Orbit and physical properties

Eidolon physically orbits Uclea in approximately 32.73 sols and returns to the same observed phase every thirty-six. It lies about 125,000 kilometres from Uclea's centre and is roughly 1,200 kilometres across. Its low-density rock-ice body has weak gravity and little atmosphere.

Appearance

Despite its small size, Eidolon appears about 0.55 degrees across because of its proximity, close to the apparent size of Earth's Moon. Its phases structure inherited @Imperial, Callandorian, Duchian and Allied-Crowns timekeeping.

Spaceflight

In the Iota alternate history, the first decisive evidence for consciousness fading with distance from Uclea emerges during the Eidolon missions. The staffed EIDOLON-3 installation becomes associated with the phrase “station is calm” as behavioural variation and initiative disappear.