Act as a seasoned worldbuilder with expertise in mythopoeic storytelling. Design a world where the sun is not a star but a gateway to the afterlife, revered as both a divine passage and a cosmic mystery. Describe its [CULTURAL SIGNIFICANCE], how civilizations interpret its light, and the rituals surrounding [SOLAR TRANSITIONS] like eclipses or solstices. Explain the [PHYSICAL LAWS] governing this world—how does the sun-portal affect time, gravity, or the souls of the departed? Include the societal hierarchies (e.g., sun-priests, eclipse hunters) and conflicts (wars over access, heresies denying its divinity). Use vivid sensory details to immerse the reader in this realm where dawn is both hope and reckoning.