The World of Aia
Aia is a spinning flat disc approximating 2,000 miles in diameter ringed by a tremendous swirling blizzard upon its rim which sits atop a vast ocean of heavy liquid called the Blackwater, of such density that even lead will float. Beyond this is the astronomers’ hypothesized Telluric Veil, which separates the heavens from the Blackwater.
Aia is obviously flat because there is no curvature; on a flat ocean, one can see for nearly ~20 miles before atmospheric scattering blinds you.
The Sun
Aia’s Sun does not consistently rise in the east & set in the west. Instead, it appears to change orbits on a daily basis, because Aia (or possibly the external cosmos) is spinning. Because the sun’s position changes on a daily basis, sundials do not work on Aia unless rotated to match the sun’s new location at the start of every day.
The Sun is not known to be round, but is believed to be so. It is believed to be around the same size as the Moon & obviously orbits closer to Aia than the Moon as it occasionally passes between the Moon & Aia (a “solar eclipse”).
The Moon
There is a kingdom on the Moon & it hates you. It will never extend its fabulous & wonderful offerings, except to those kings who can provide what the Moon lacks. Through the dense white swirling clouds, you can occasionally glimpse their crystalline spires — and only ever will you glimpse it.
The Moon appears to bob up & down in the sky, serving as the “north star” from the 8th (when it first rises above the Rim Blizzard) to the 22nd (when it dips below the horizon). It does so because it orbits Aia at the same rate that Aia spins (a period of precisely 30 days), but at an incline of around 40°.
The Moon is obviously round because it catches light from the Sun in the same manner that a sphere in its place would; it has an extraordinarily unpredictable day/night rhythm as a result, but it is usually shrouded in dense clouds anyways, so it is hypothesized to be bleak & stormy.
Astronomers believe the Moon to be around 300 miles in diameter & situated at a distance of 5,000 to 8,000 miles from the center of Aia, or around 3,000 miles from the Telluric Veil.