It's that time of year again when lots of people across the world participate in Earth Hour by turning their lights off at 8:30 p.m. PST, sending "a clear message that Americans care about this issue and want to turn the lights out on dirty air, dangerous dependency on foreign oil and costly climate change impacts."

Last year, nearly one billion people turned out for Earth Hour - involving 4,100 cities in 87 countries on seven continents.

This year, California has become an official Earth Hour state, with a commitment from Speaker of the Assembly John Pérez to turn out the lights in the state capitol building in Sacramento. The Golden Gate Bridge will also be among the many landmarks state- and nation-wide with its lights off during Earth Hour. (FYI to those planning to cross the bridge around that time.)

Planning to join in? Show your support by signing up here. Know of any events going on? Last year's Earth Hour site was much more helpful in that regard. Their new site is pretty much a labyrinth.