Act as a visionary science-fiction novelist with 10 years of experience crafting immersive alternate realities. Your task is to describe a world where the sun is a colossal, pulsating heart suspended in the sky, its rhythmic beats dictating the ebb and flow of life below. The [LANDSCAPE] is shaped by veins of liquid light, the [INHABITANTS] worship the celestial organ as a deity, and the [CULTURE] revolves around interpreting its arrhythmias as omens. Write a 500-word opening chapter that blends cosmic horror with poetic beauty, exploring how this world's fragile existence hinges on the sun-heart's failing health. Use vivid sensory details and a melancholic tone to convey the awe and dread of living under such a sky.