500 years before Tilted Sun’s events take place, humanity converts Saturn into a sun. The technology and knowledge of those who converted the planet are now long lost, and current residents of Titan, Rhea, and the other moons can only wonder and fantasize about what made Saturn shine. It provides warmth and light enough to make Titan 60-85 degrees Fahrenheit.
When Titan citizens speak of Saturn, they refer to it as Our Tilted Sun.
Occasionally, Saturnic flares are known to happen and this can affect life on Titan, making for especially hot weather. Saturnic flares can also disable interpreters that rely on radio.
The First Sun of the Solar System is still active, but it is too far away to warm up the residents of Titan, Rhea, or the other moons. Very little of “planets” are known. For this reason and many others, the Old Books of Planetary History are sought out by many artifact hunters, Helixers, and powerful people across Titan.