Thursday, August 16, 2007

Let There Be (Less) Light

The current New Yorker magazine has a must-read article by David Owen on how our obsession with abolishing night through an evermore blazing slather of artificial lighting is disconnecting us from the cosmos by rendering it invisible.

Four centuries ago, Galileo, with a telescope so primitive that today it would be considered a children's toy, was able to see the the moons of Jupiter as well as the mountains of the moon. In our own time, "light pollution" has made this impossible in all but a dwindling number of remote locations such as the outback of Australia or the mountains of Peru. Owen notes that even standing on the North Rim of the Grand Canyon on a dark night, the brightest thing is the sky is not the Milky Way, but "the glow of Las Vegas, a hundred and seventy-five miles away." The sight of a sky flooded with stars blinking on and off is something most of us now experience only through a CGI cliche.

Owen chronicles the ongoing efforts of the International Dark Sky Association to return us to a darker world, which sounds like flake city until you realize how much of the energy we expend on night lighting is hugely wasteful and, at times, counterproductive, even destructive. He talks of "glare bombs", lighting fixtures that cast much of their light sideways, into the eyes of pedestrians, creating glare that actually decreases visibility, or upward, uselessly up into the sky.

New codes, like those in Tucson, mandate outdoor lighting that is of a "full cutoff" or "fully shielded" type, casting "no light above the horizontal plane and employ a light source that cannot be seen by someone standing to the side." Moving to that kind of lighting has recently saved the city of Calgary, Canada, roughly two million dollars a year.

Nighttime visibility is about contrast, and the blight of light actually undermines our vision's natural capacity to acclimate to - and perceive objects in - darkness. Human night vision is acute, but the rods in our eyes that make it possible can take a hour to adjust after exposure to something no brighter than a desk lamp.

Owen relates how indiscriminately bright night lighting actually becomes "criminal-friendly." A burglar whose flashlight is the brightest object is immediately conspicuous; one operating in the massive shadows created by glare bombs is not. There may even be major health implications. Harvard's Nurses' Health Study has speculated that many medical problems - night shift workers having an increased risk for breast cancer, for example - can be traced to the lack of melatonin, "a cancer-protective agent whose production is severely diminished in people exposed to light at night."

Excess nighttime lighting can have devastating effects on migratory birds, at times killing thousands in a single night. (In Chicago, this has led to getting skyscrapers like the Hancock to turn down their lighting during migratory seasons.) Bright lights have been linked to the decimation of insect populations, and in Florida, of sea turtles. Newborn turtles are drawn to the brightest horizon. "For millions of years," says Owen, that has been "the night sky over the open sea." The cover of darkness protected their journey, but today, the turtles may just as easily be drawn to the open parking lot of a floodlit shopping mall, where they find themselves lit up in a way that advertises a "come-and-get-it" ease to their predators. Think Mrs. Venable's cheery tale in Suddenly, Last Summer.

It's a fascinating read, well worth the $4.50 cover price of the print version of The New Yorker, which you'll have to shell out because the article isn't on their website.


Mitch said...

I can symapathize with this article. I've been out on Lake Michigan and have marvelled at the sky when up north and also marvelled at the powerful glow Chicago can cast too. Nearly all the way to St. Joe, Michigan and you can still see Chicago quite clearly.

However, I would also argue it may not be light, but the quality of that light. Look at pictures of New York City and Chicago from the 20's and you'll see a city bathed in the glow of thousands of bulbs and neon.

Look at the old terra cotta buildings on the North Side of Chicago and you'll see hundreds of filled little holes where light bulbs once glowed. Imagine the beauty of the once huge neon signs illuminating the old Uptown Theatre, or the Congress, or a large retail store.

The skimpy neon signs one sees today can only hint of what our grandparents were privvy to in their day.

Let there be light.

Anonymous said...

The Museum of Science and Industry has a new installation opening in September called Earth Revealed. It's a 6-foot globe with projections of NOAA and NASA data. Someone who has seen it already says that the human-made lighting is the first thing you notice.

Dean W. Armstrong said...

In Chicago, we could literally save millions of dollars a year by switching to more-efficient fully shielded streetlights, like the ones on south Lake Shore Drive, as long as instead of using higher-wattage bulbs, we take the efficiency increase and use a lower-wattage bulb to produce the same amount of light on the ground. The typical crimebuster light in Chicago loses 30% of its light up, which lights nothing but birds and peoples' 2nd and 3rd story bedroom windows.
A post about astronomy communities and Chicago light pollution

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