On March 27, 2010, millions of people will turn off their lights for an hour, at 8:30 PM local time, to celebrate Earth Hour. "Since its inception three years ago, Earth Hour's non-partisan approach has captured the world's imagination and became a global phenomenon," says Earth Hour's official U.S. site. "Nearly one billion people turned out for Earth Hour 2009--involving 4,100 cities in 87 countries on seven continents. Last year, 80 million Americans and 318 U.S. cities officially voted for action with their light switch, joining iconic landmarks from around the world that went dark for Earth Hour"--like the Empire State Building, Brooklyn Bridge, Las Vegas Strip, Big Ben, and Sydney's Opera House. Check out Earth Hour social media tools here and also at the Earth Hour Blog; bloggers are encouraged to blog about Earth Hour, and many are already doing so.

Earth911 notes that this year, “Earth Hour now boasts 34 more participating countries, including Nepal, Mongolia, Pakistan, Paraguay, Zimbabwe, Uruguay, Macau, Sri Lanka, Tanzania, Czech Republic and Madagascar.” And Ecorazzi says, “Celebrities like Gisele, Tom Brady, Leona Lewis, and Edward Norton have all advocated for worldwide participation in the event.” At Ecoki, share your plans for Earth Hour. baby gooroo suggests turning off TVs and computers too and playing flashlight tag. Life Candy might tell ghost stories. And Astroblog has ideas for throwing a star party.

What are you doing for Earth Hour?