|These photos show the skyline of Sydney in Australia before and during Earth Hour
in 2007. On Saturday, about 200 cities around the world are due to take part.
Lights are going dark for a round-the-world, voluntary rolling blackout at 8 p.m. local time Saturday. Earth Hour - which originated in Australia a year ago and is now going global, thanks to the World Wildlife Fund - focuses awareness on saving energy and doing something about climate change. But the turn to the dark side didn't just begin last year, and it's about much more than one consciousness-raising hour. Saturday night also marks the beginning of a whole week of activities aimed at making our skies darker for good.
National Dark-Sky Week got its start five years ago - and this year, the week's organizers are teaming up with Earth Hour (as well as the folks behind Lights Out America) to support Saturday's hourlong celebration of the dark side. In hundreds of cities around the world, people will be dousing their lights from 8 to 9 p.m. local time as a symbolic gesture for action on the climate change issue.
During that hour, some folks will be hosting Earth Hour candlelight dinners. Others will be staging glow-in-the-dark Frisbee games. But for stargazers, Earth Hour and Dark-Sky Week offer golden opportunities to see the night sky the way it was meant to be seen, at least partly free of the glare from urban lights. That's why scores of astronomy clubs are sponsoring star parties over the next few nights. (To find a club near you, check this Web link, and this one, plus this one, and this one.)
"National Dark-Sky Week is a great opportunity to dust off the old telescope from the attic and share in the wonder of the universe that has been part of the human tradition for thousands of years," the event's founder, Jennifer Barlow, said in a statement distributed by the International Dark-Sky Association.
The association's senior technical adviser, Pete Strasser, said surveys have shown that 90 percent or more of all Americans younger than 18 have never seen the glow of the Milky Way galaxy with their own eyes. "They literally don't know what they're missing," Strasser said.
People may think it has to be that way in order to protect the streets from predators that lurk in the dark. But Strasser, who lives in Tucson, Ariz., said that's mostly a case of "fearmongering."
He said the fault lies in poorly designed urban lighting systems, which waste most of their light by shining it up into the sky.
"Our crime rate is no higher or worse than any other community's, and yet I can see the Milky Way from my driveway at night, in an area with a population of over a million people," he said.
In Strasser's view, Americans can have their safety as well as the stars. "Our organization says 'Dark-Sky,' it doesn't say 'dark ground,'" he said. "Reasonable lighting practices will solve the problem."
Street lights, for example, can be shielded on top so that more of the light is aimed directly on the ground, and less of it is wasted on the sky. At home, outdoor lighting systems can be equipped with timers and sensors to keep the lights dark when they're not needed. Environmentally friendly, energy-efficient lamps can make a huge difference. The Dark-Sky Association's list of frequently asked questions provides plenty of tips and loads of Web links.
Stargazers will be among the big beneficiaries of darker skies, to be sure, but there'll be a benefit even if you don't look up into the heavens.
"The conception of the whole dark-sky impact has evolved from astronomical concerns into a broader spectrum. ... Of our 12,000 members, 5 percent are astronomers," Strasser said.
The wiser use of lighting - outdoors as well as indoors - is much more than a symbolic one-night gesture. Lighting represents as much as 25 percent of residential electrical use, and up-to-date technologies can cut that consumption by more than half. You can get those savings by switching to compact fluorescent lights or LEDs, by getting smarter about sensors, and by simply switching off the lights in empty rooms.
For more about Earth Hour, check out this dispatch from NBC Field Notes. For more about light pollution, there's this report from U.S. News and World Report. And to see the glories of the night sky from your computer, click through the latest installment of our "Space Shots" slide show.
Update for 3:05 a.m. ET March 29: Based on the comments coming in, some people may have gotten the misimpression that the cities participating in Earth Hour would somehow shut down the power grid or force people to turn their lights off. This event is totally voluntary, and of course no one will force you to go dark. I'd expect that traffic lights and other lights judged essential for public safety will stay on as usual.
In the Earth Hour cities, there will be special events, and I'm betting that a lot of the lights that are kept burning in empty offices may be turned off for at least an hour. But it's totally up to you whether you want to turn any of the lights off at your house. I've added the word "voluntary" in the frst paragraph in hopes that will make the situation clearer. Check the Earth Hour Web site for lists of cities that are project partners or supporters.