I mentioned Astronomy in the game #3 post, so might as well expand on the idea for the readers who have no idea what I am talking about.
The basic premise is that objects in the night sky circle around The World, not the other way round. Other important thing to note in the start is that without light the world would be basking in grayness, not in darkness. Darkness and Light are both active forces - thus, objects shine light or shine darkness. Of the elements - Earth shines darkness around it, Fire shines light. This means that underground passages are still dark and objects still cast shadows. The shadows just aren’t there because of the lack of light, it’s because other objects are shining some darkness on them.
Anyways, this is relevant to Astronomy because there are two suns orbiting The World. Both having the same orbit, both opposite to each other on it. One of the suns shines light, the other shines darkness. Thus forming day and night. Each of the suns has a companion, a moon. that orbits them. The moons are as large as the suns they orbit, but have far less strength to shine light/dark. The dark sun’s companion is a moon that shines some light. It takes the moon 30 days to go around the dark sun. From the point of view of a regular viewer it means that the moon is full about 15 days of the month, waxes for 7, wanes for 7 and disappears from the view for 1 day. The light sun has a companion dark moon, that has a substantially longer orbit. It takes it 360 days to do a full circle, meaning that the sun is fully seen from The World for 180 days, partly seen for 160 and is nearly/fully gone from sight for about 20 days a year.
The days don’t grow longer and shorter when days pass in a year, but the cold and warmth do vary thanks to the amount of Light (that also contains warmth, thanks to its relation with Fire) that gets to The World.
Beyond the Suns and the Moons, there is the celestial dome. It is a literary dome, with either small holes or mirror-like bits in that we see as stars. During the hottest days of midsummer, you can make out small dark stars in the day sky just like you can see stars in the night sky the brightest when you can’t really see the moon.
It is said that the suns/moons are the eyes of The Creator and that the stars are actually His angels, waiting to descend back to The World when the last days arrive, but most scientists dismiss these theories.