The Eclipses

Ulaan is part of a binary star system and the two stars orbit each other very slowly. It takes 33 years for the stars to make one complete orbit, leading to a lot of cultures' religious ceremonies revolving around this 33-year cycle. 

The first sun, Ast, is a bright yellow star very similar to our own Sun. The second sun, Hata, is a smaller red dwarf (1/3 the size of Ast) that is the main source of solar magic. The mixing of the radiations is what creates the magical solar energy that the planet runs on.

When both Hata and Ast are visible, magic functions as it does normally. Once Hata begins to cross in front of Ast, the magic begins to become more powerful and unstable. Magicians and spellcasters become much more powerful, and some technology that runs on magic may malfunction.

When Hata is directly in the center of Ast, it appears like there is a gigantic eye looking down on the planet. Magic is at the height of its power, and can become dangerous to those who don't know how to wield such power.

When Hata moves behind Ast, magic becomes less powerful, so magic users are weaker. The technology some rely on may not even work because there is no source of power. With the rise of Sky Whale oil, it has become a way for people to survive during the long dark period.