Hudbyd, the world which contains the continent of Agnara, is a satellite world in orbit around a Jupiter-mass planet which is itself in orbit around a sun-like star in an earth-like orbit. (Convenient, that….)
There are other satellite worlds in orbit around the gas giant, and on occasion their orbits result in close passes between worlds.
Hudbyd itself is one of the farthest orbiting satellite worlds, and as such the gas giant is a rather small object in the sky. Hudbyd orbits the gas giant in roughly 30 days. The resulting geometry of the system ends up with the gas giant appearing to go through phases as Hudbyd finds itself on different sides of the gas giant compared to the sun.
Hudbyd rotates on its axis in a roughly 24 hour cycle. The variance in the orbits of the gas giant and Hudbyd result in infrequent eclipses of the sun.
The other satellite worlds that can be seen from Hudbyd are known as the “racing wanderers” since they move so rapidly and seemingly unpredicatably compared to the background stars. There are other “wanderers” visible as well, which are slower and not as easily noticed by casual observers. These wanderers are planets in other orbits, similar to our planets.
Most of the known world breaks the monthly cycle of orbits around the gas giant into four weeks of seven days each. Every three months a six-day holiday is declared to restore the weekly cycle to be in sync with the monthly orbit. In this way the “new moon” is always on the first, second or third day of the month, and the full moon is always on the 14th, 15th or 16th day of the month. The yearly orbit around the sun is broken into twelve months of 30 days each. The year is close enough to 360 days that adjustments are only needed every fifty years or so.
The days of the week have names, as do the months, but those names tend to detract from game play so months and days are generally referred to using earthly names to make things easier for game play.