Monday, March 5, 2012

Look'd up in perfect silence at the stars, but the stars weren't there.

The Meadville sky at night is a little sickly looking in the space above the parking lots. There are hardly any stars to find in the strange pink haze that stretches across campus and toward a dotted cluster of lights in town. It is 11 PM, and I can still see the dim white outlines of clouds.

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
Light pollution is a uniquely modern problem, a product of our urban success. Outdoor lighting is overused and misused; lamps are carelessly pointed upwards, lights are left on when they are not needed. You can see the proof in metropolitan skylines. Cities bask in the yellow aura they create, which gives their skyline a pleasant, mystical quality in photos. You can see it from afar in iconic NASA images of nighttime on Earth

Eastern US at night, January 2012
Photo credit: NASA
Light pollution has left astronomers frustrated for years. Residual light interferes with their ability to conduct research, even with the benefit of professional telescopes. The opportunity to be an amateur stargazer without a telescope is waning quickly, too, with so many subpar skies. It is possible to grow up having never seen the Milky Way; I did, and so will the other 82% of Americans living in urban areas.

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.

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