Artificial Light Has Made Life Easier — Unless You’re an Astronomer

Artificial light has transformed human society. It frees us from the darkness, and allows us to light our homes and communities. It has also made the night sky increasingly less dark, which poses a challenge to astronomers. And it’s gotten worse in recent years, thanks to an energy-saving light known as LEDs. The earliest light bulbs (of Edison fame) were extremely inefficient. They produce incandescent light by electrically heating a thin wire of metal to the point that it emits light. But only a small fraction of the light emitted is visible. Most of it is infrared, which we feel as heat. The bulbs make much better heaters than lights, and for a time there were even toy ovens that used a light bulb to bake little cookies or muffins. Their big advantage was that they were cheap and reliable.