Pull of the Stars
The people of Urth are not alone in their universe. Demons rush forth from the Void¸ devils torment the wicked in Hell¸ and the faeries plot and dance in hidden kingdoms-yet worlds just as strange drift nakedly visible across the night sky. Power radiates from innumerable stars¸ while traumatic shockwaves pulse across the cosmos¸ the final screams of entire civilizations consumed by the Demon Lord's shadow. The seeming emptiness is filled with half-thoughts from idiotic star gods¸ the psychic wails of dying races¸ and the tremendous bursts of gravity as black holes collide. The prison moon of Tarterus shields the minds of mortals¸ elementals¸ and fey alike¸ but this protection is imperfect¸ and venturing out to explore and exploit those other worlds comes at great risk.
Madness is all too common among both astronomers and seekers who set foot on alien soils. It has innumerable forms and symptoms¸ but a common refrain is that something wants to be known. Moons full of the bastard offspring of the genies' insanity¸ mooncalves born of mortal creatures exposed to the energies of the aether¸ and artifacts of dreadful knowledge-all seem to join in a single song. Such whispers of a grand cosmic agenda are dismissed on Urth as paranoid¸ but it is impossible to deny that those exposed to the cosmos change in specific ways.