Our Nights are Getting Brighter, and Earth is Paying the Price
Electric lights have revolutionized our lives, but as illumination increases, the toll on wildlife and human health is becoming harder to ignore.
A Sky Quality Meter measures the nighttime brightness in central Los Angeles; results lower than 20 indicate more light polluted skies. Researcher Christopher Kyba suspects that such ground-based measurements are more accurate than satellite-based assessments, which currently cannot detect certain wavelengths of light.
BABAK TAFRESHI
On a clear night in 1994, an earthquake rumbled beneath Los Angeles and caused a city-wide power outage just before dawn. Startled awake, some residents who had stumbled outside called various emergency centers and a local observatory to report a mysterious cloud overhead.
That weird object turned out to be the band of the Milky Way, our home galaxy, which had long been obscured from view by the city’s lights.
Arguably, the light bulb is the most transformative invention humans have introduced to this planet. By flicking a switch or pushing a button, we can push back the veil that would naturally shroud our lives each night. Now, we work long after the sun sinks below the horizon. We play games outside until the hours stretch into double digits. We more safely roam city streets after dark.
But if light bulbs have a dark side, it’s that they have stolen the night. The excess light we dump into our environments is endangering ecosystems by harming animals whose life cycles depend on dark. We’re endangering ourselves by altering the biochemical rhythms that normally ebb and flow with natural light levels. And in a primal sense, we’ve lost our connection to nighttime skies, the tapestries into which our ancestors wove their star-studded stories, timed the planting and harvesting of crops, and deduced the physical laws governing the cosmos.
