Billions of people to turn lights off to mark Earth Hour 2011 event

CANBERRA, Australia - Billions of people from more than 130 countries are expected to turn off their lights on Saturday for Earth Hour 2011, the event's organizer said on Thursday.

Earth Hour, organized by environment group World Wildlife Fund (WWF), was first started in Sydney, Australia, in 2007 with 2.2 million people taking part to turn off their lights in aid of the environment.

By 2009, up to 1 billion citizens across the world had taken part.