By Bill Marvel
Ah, no longer. Unless you live in a remote desert or on a mountaintop, these days the heavens mostly show forth the operations of the local electric utility. And the firmament — when you can see any firmament — is a washed-out glare of stray light, sprinkled with a handful of pale stars.
We humans came of age gazing at the night sky. The movement of the stars and planets taught us to keep track of the seasons, and ultimately made us thinking beings. Yet ever since the invention of the dynamo we have progressively deprived ourselves of this sublime sight by spilling artificial light into the atmosphere. The loss is not just cultural or spiritual. It’s financial and environmental. Every stray photon of light that passes into the sky is one more that doesn’t illuminate our paths and doorways. We might as well go outside and throw handfuls of dollars at the sky.
The average American household spends 5 to 10 percent of its energy dollars on lighting. Long after everyone’s in bed and lights inside the house are switched off, yard lights blaze on. An ordinary incandescent bulb casting its glare over a suburban backyard, if it’s unshielded, pumps up to 60 percent of its illumination into thin air, where it reappears as the persistent sky glow that hangs over every American city. Add to this improperly shielded “cobra-head” and “acorn” street lamps, the glaring wall-packs on convenience stores, banks and ATMs, and high-pressure sodium and mercury vapor lamps, and the phrase “burning the midnight oil” takes on an ominous new meaning.
Experts say that to create all this wasted light power plants must produce energy equivalent to burning an extra 6 million tons of coal a year. That’s the contents of three fully-loaded unit coal trains every two days, reduced to ash, various pollutants, and CO2.
The annual cost in dollars is estimated at $9 billion. All to make the stars invisible. (See the photo above of an over-lit night sky above a city, which contrasts with the top picture of a clear view of the galaxy. Both photos reprinted courtesy of the International Night-Sky Association. Picture to the left of North America from space, NASA).
Naturally, stargazers were the first to notice the problem. By the early 20th century, astronomers were already moving their telescopes further and further into the countryside to escape the glow. But as cities grew and suburbia sprawled, the glow followed.