Turn Your Lights Out For Earth Hour: March 28, 8:30 p.m.

Hundreds of thousands of people across the globe have already signed up to flip the switch tomorrow for Earth Hour 2009. Last year's event was the largest voluntary power-down ever: More than 50 million people in 35 countries turned off their lights for 60 minutes.

This year, iconic landmarks around the world are also going dark for the hour, including New York's Empire State Building, the Las Vegas Strip (!), San Francisco's Golden Gate Bridge, Seattle's Space Needle, Chicago's Sears Tower, Paris's Eiffel Tower, Egypt's pyramids, Greece's Acropolis, and the Sydney Opera House.

The campaign started in Sydney in 2007. That year the city's carbon consumption dropped by more than 10 percent during Earth Hour. If Sydney maintained that level of energy reduction year-round, it would be the equivalent of taking almost 50,000 cars off the road. To pledge your participation, sign up at this link -- and tomorrow, March 28, go dark between 8:30 and 9:30 p.m.

Just don't compensate for the darkness by burning a candle: Experts say that candles are 10 times worse for the environment than lightbulbs.

--Avital Binshtock