World map of current light pollution, as of 2016. The brighter colors, shown in whites and reds, represent the areas where light pollution is greatest. A combination of population density and per-capita wealth correlates extraordinarily well with the amount of light pollution present. (F. FALCHI ET AL., SCIENCE ADVANCES, 10 JUN 2016)

This Is How To Bring Dark Skies Back In An Increasingly Developed World

Well-lit cities and towns are essential to public safety. That doesn’t have to ruin the night sky.

For most of us here on planet Earth, navigating the world at night is just a little more challenging than during daytime. Without the Sun’s bright light to illuminate our world, our eyes do their best to adapt. Our color-sensing cones move back in our eyes while the monochrome-sensitive rods move forward. Our pupils dilate to larger diameters, letting more light in. Even in the wild, the Moon and stars provide enough light for a sufficiently dark-adapted eye to make out shapes and objects.

Evolutionarily, this was a spectacularly useful adaptation. Human vision may be optimally suited to daytime vision, but the ways our eyes adjust also allow us to perceive the Universe far beyond our world. Unfortunately, our connection with the night sky has been severed by a truly human endeavor: artificial lighting. While the benefits to public safety and commerce are inarguable, the tradeoff is unnecessary. Light pollution may a worse problem than ever, but it doesn’t have to be this way.