Some 147 countries worldwide marked the annual Earth Hour on Saturday, an event prompted by the World Wildlife Fund since 2007. Hundreds of landmarks around the world, including Sydney's iconic Harbor Bridge and Opera House, Washington's National Cathedral, Big Ben in London, the Great Wall of China and Tokyo Tower were dimmed at 8:30 pm of their respective local times. The Great Wall of China (Photo: AFP) Millions of people joined the effort as well, turning of lights in homes and businesses worldwide. The WWF said that the number of countries and territories participating has grown from 135 last year to 147 this year. This year, newcomers included Libya, Algeria, Bhutan and French Guinea. Temples in Indonesia (PhotoL AP) "Earth Hour 2012 is a celebration of people power the world's largest mass event in support of the planet," WWF official Dermot O'Gorman told reporters in Sydney, Australia. Main street in Moscow (Photo: EPA) Australia is traditionally the first country every year to dim its lights in honor of Earth Hour. "And we're seeing hundreds of millions of people in different countries around the world take actions to go beyond the hour in support of positive actions for climate change and the planet," he said AP contributed to this report Follow Ynetnews on Facebook and Twitter