Question

Read the following passage carefully and answer the questions that follow. For most of human history, night meant darkness, and darkness set the rhythm of sleep, work and rest. The electric bulb has now erased that boundary. Two-thirds of the world's population lives under skies bright enough to hide the Milky Way, and the glow keeps spreading at about two percent a year. Astronomers were the first to protest: observatories that once recorded the faintest galaxies now fight a wash of orange haze. But the costs reach far beyond telescopes. Migratory birds, which navigate by the stars, are lured into collisions with lit towers; newly hatched sea turtles crawl towards beachfront lamps instead of the moonlit surf; and nocturnal pollinators, drawn to streetlights, abandon the flowers they were meant to serve. Human health is implicated too: exposure to artificial light after sunset suppresses melatonin, the hormone that signals sleep, and shift workers - those most bathed in night light - show higher rates of metabolic and cardiovascular disorders. None of this means cities must go dark. Shielded lamps that throw light downward, warmer colour temperatures, motion sensors and curfews on billboard lighting can cut the waste sharply; much of the light now staining the sky is simply light that never reached the ground. The night sky, once free to all, has become a resource we spend without counting. Conserving it will require the same habits we already apply to water and fuel: measuring the waste, designing for efficiency and deciding how much darkness we are willing to keep.