From Denver to Sydney to China and London, thousands of cities, businesses and individuals around the world are flipping the light switch to the off position and going dark for one hour Saturday night in celebration of Earth Hour.
At 8:30 p.m. local time, famous landmarks such as the Great Wall of China, Sydney Opera House, London's Big Ben and the Empire State Building, will go dark to raise global awareness of environmental issues such as global warming.
According to the Earth Hour's website, more than 7000 cities and towns across 152 countries are participating in this year's event.
The first Earth Day was celebrated in 2007 in Australia. The initiative was led by the World Wildlife Fund, an international conservation organization.
So if the lights go out where you are, it may not be a power outage, just people joining together to give Mother Earth an hour of rest – in the dark.
To learn more about Earth Hour, visit http://www.earthhour.org/