Lights Out: Millions to Recognize 'Earth Hour' at 8:30 p.m.

At 8:30 p.m. Saturday, non-essential lighting at usually well-lit landmarks across the globe—like the Empire State Building and the Great Wall of China— will be turned off for one hour. Earth Hour 2012, an initiative of the World Wildlife Fund, has even compelled 20 National Hockey League teams to dim their lights during game time. 

Earth Hour, which began five years ago in Sydney, Australia, will be observed by 147 countries and thousands of cities. Even the crew on the International Space Station will participate, according to the Huffington Post. 

Electricity accounts for 41 percent of earth's carbon emissions, according to the U.S. Environmental Protection Agency. 

According to the Earth Hour website: "In 2011, Earth Hour saw hundreds of millions of people across 135 countries switch off for an hour. But it also marked the start of something new—going "Beyond the Hour" to commit to lasting action on climate change. And with the power of social networks behind the Earth Hour message, we hope to attract even more participation so we can build a truly global community committed to creating a more sustainable planet."