Some creature or creatures regularly (sunrise and sunset, summer and winter, lunar phases) or irregularly (solar and lunar eclipses, eschatological events) attack the luminaries or shade their light
Giant reptilian monster (serpent, more rare fish, chain of fish) extends in the sky and/or supports the sky being associated with Milky Way or the rainbow
Mother dies or is killed. Her (still unborn) baby-son is buried with her. He comes out of the grace, meets people, then returns to the grave but ultimately agrees to remain with the people