When you design a world for your RPG how much effort do you put into astronomy?
There are many reasons why you would want to keep the sky very similar to Earth. You’d want 24 hour days and 7 day weeks unless you want players to try and memorise new calendars. You might also want standard seasons.
There are also RPGs set on worlds that are always in night.
If you do want to make the skies a little more exotic – perhaps to give your world an un-Earthlike feel – then consider the distance between the sun and your planet.