Thousands of years ago the world ended. Why the world ended and how the world ended is mostly forgotten. Today the world is made up of floating islands. These islands revolve in no discernable pattern, though experienced skyship captains are able to estimate within a few weeks how long a trip will take.
There is no sun, or moon, or day, or night, nor is there any memory of such things. Instead, there is the ever-present Voidglow. The glow comes from everywhere at once. There is no origin of the glow, it simply is everywhere at once. The only time you are not in the presence of the glow is when you are in the shade of an inanimate object or indoors. Intelligent life does not create a shadow.
Avoiding the glow is a large part of any islander’s life. Many islanders on the larger or more prosperous islands have devised ways to spend most of their day to day life out of the glow. Unfortunately, people who live on smaller or poorer islands are not so lucky and glowmadness is a regular part of their life.
The various ways people avoid the glow depends on the island. For example, on the island of Canopy islanders spend their days in the shade of the mighty pines that cover most of that island. On the other hand, citizens of Bridgeways are not so lucky. Most of the bridges and roads are uncovered which means many islanders have to brave the glow to go about their daily business.