Study of the stars, is, of course, as big a deal in my world as in the real one. A lot of religions have beliefs associated with certain stars or constellations, and mariners use the stars to navigate by. The world is generally known to be round (by anyone who bothers to look into the matter), and the stars are assumed to lie in an outer sphere that rotates around Aerith. The sun, moon, and planets are (obviously) various kinds of celestial objects that travel around Aerith in their different paths. There is no Pole Star, but there is the "Guardian Star", Gilmoreth, (whose origins are explained in the Book of Sulan) that is known to lie in a fixed position above Aerith, and by relating that to an estimated position of the pole, latitude and longitude can be determined. Telescopes exist, but they are far beyond the ability of all but the wealthiest of kings to buy, and good ones are even rarer.  Spyglasses and refracting telescopes are available, and no ship sails on open water without one.  The year is divided into ten months of 36 days each. In the star chart below, the names of the months are the ones on the outside.  The constellation relating to the month name is the one currently hidden behind Sollux (the sun).  Thus, the stars you'd see that month are the ones on the opposite site of the chart.

    Aerith has two moons - Agrina the Huntress, a large, pale orb with an angular diameter of about 1º - roughly twice the size of Luna in Earth's sky.  This means that on nights where Agrina is full (and I haven't gotten around to deciding on its orbital properties yet) - there is a lot of light.  More than enough for humans and other creatures without the benefit of infravision to see an operate more or less normally.  The second moon, called Weedle the Mouse (until I think of a better name), is a tiny speck compared to Agrina, and moves across the sky much faster.  So fast, in fact, that the movement can be easily seen - one can lay down on a lazy afternoon or a clear night and watch him race the clouds.  The story behind the names is that Agrina was once the greatest huntress on Aerith, but through some as-yet-uninvented set of undoubtedly humorous circumstances, she was cursed to remain in the sky until she could catch Weedle, a mouse too small and quick for her to hit with her bow.  So, they move around Aerith in an eternal chase. . .