That cluster of lights in the distance is a problem. The town, with all its lampposts and security floodlights, casts a continuous glow upward that lingers in the atmosphere and washes out the pitch of nighttime. This loss of darkness is called light pollution, and I’m not the only one noticing it.
|Light pollution creeping up the mountains of the Canary Islands, Spain.|
(Significantly prettier than downtown Meadville; sorry Meadville)
Photo credit: Cestomano
|Eastern US at night, January 2012|
Photo credit: NASA
A man named John Bortle came up with a system for gauging the excellence of a sky for stargazing. Classes range from one (pure, blissful darkness) to nine (inner-city, hazy washout). To get to a Class 1 sky, you'll have to do something drastic: say, hike into the deserts of Arizona or float yourself out to the middle of an ocean. Maybe you could travel to Big Bend National Park in Texas. The park has just gained International Dark Park Status to protect the darkest sky in the contiguous United States. It is one of only 10 Dark Parks in the world (Cherry Springs State Park in PA is another).
|The Bortle Dark Sky Scale|
Photo credit: Raj Chanian's Astrophysics Blog
A few years ago, I set out to my backyard in Pittsburgh with a tripod, an SLR, and a timer set for star-trail photos. After several hours of exposure, I should have returned to a shot of wide, sweeping light arcs tracing out star paths. Instead, I was left with sad, de-saturated images blown out by the suburban light creeping in. The results were the same each day I tried my setup. I simply cannot access the night sky from my house, which is a strange and alienating feeling. What was once a communal source of entertainment and education is now a luxury of rural and ininhabited areas.
Romantic concerns for a clear night sky aside, there are plenty of reasons to worry about light pollution. Light pointed up is light wasted and energy wasted. It keeps us sleepless and stirring in the night; billboards and bright streetlights pose hazards to our biological rhythms when they shine into our windows. Trees have trouble adjusting to seasonal changes. Migrating birds that depend upon a natural horizon of light become disoriented by horizons of artificial light and fly into lit windows. Every year, over 10,000 birds passing through New York City will crash into a building on their way. In fact, all sorts of nocturnal creatures (bees, moths, insects) are wired to find their way around with the help of a strip of polarized light that stretches out from the moon on a clear night. Light pollution throws them off. It throws everyone off.
|One bright light's difference in stargazing clarity.|
Photo credit: Cali Traina
So, how do we stop light pollution? Cover lights properly, don't point them upwards, shut them off if you don't need them. Pay attention to what sorts of lawn lamps and security lights you pick up at the hardware store. If it will help -- drive out to rural areas with open fields, lay down for a bit, and see what you're missing.
Right now, we're creating our own constellations of lit windows and lanterns --a cluster of lights seen from a campus parking lot two miles away. If you ask me, it's all poor substitute for the real thing.