For most of human history, the night sky was full of stars. On a clear night, anyone could look up and see thousands of them, along with the soft, cloudy band of the Milky Way. Today, more than a third of the world's population can no longer see the Milky Way from where they live. The reason is light pollution.
Light pollution is the extra artificial light that cities produce: streetlights, illuminated advertisements, parking lots, sports stadiums and millions of windows. Much of this light is wasted, because it shines upward or sideways instead of down onto the ground where it is needed. It scatters in the atmosphere and creates a glowing dome over cities that hides all but the brightest stars.
The problem is not only that we lose a beautiful view. Many animals depend on darkness. Migrating birds use the stars to navigate, and brightly lit buildings can confuse them. Newly hatched sea turtles find the sea by moving toward the brighter horizon, but city lights can lead them in the wrong direction. Even humans are affected: artificial light at night can disturb our natural sleep cycle.
In Israel, one of the best places to escape light pollution is Mitzpe Ramon, a small town on the edge of the Ramon Crater in the Negev. Despite its name, the crater was not made by a meteorite; it was shaped by millions of years of erosion. Far from big cities, on a moonless night, visitors can see the Milky Way stretching across the sky.
The good news is that light pollution is one of the easiest kinds of pollution to fix. Unlike plastic in the ocean, it disappears the moment we switch off the lights. Shielded streetlights that point downward, warmer colors, timers and motion sensors can reduce it dramatically, and they save energy and money as well. Getting the stars back may be simpler than we think.