Step outside on a clear night almost anywhere in Britain and look up. Chances are you won't see much. An orange coloured washed out glow hangs over every town and city, drowning the stars in a tide of misdirected light. Now the Royal Astronomical Society is demanding that tide be turned back, not just for the sake of astronomy, but because the evidence of what artificial light at night is doing to our health, our wildlife, and our ecosystems has become impossible to ignore. The night, it turns out, isn't just a backdrop. It's a habitat thats more entwined with our very wellbeing and health than you can possibly imagine. And we're destroying it.