Earth Hour observed all over the world

What does it look like when the world turns out all the lights?

A glimpse will be offered today when millions of participants all over the globe -- from Egypt's Tahrir Square to Washington D.C.'s National Cathedral -- are expected to turn their lights off for an hour in honor of Earth Hour.

Sydney's symbolic Opera House and Harbor Bridge were a couple of the first places to go dark, as Australians took part in the global effort to raise awareness over climate change and show the need for sustainability. The event takes place worldwide on Saturday from 8:30 to 9:30 p.m. local time, during which time people are encouraged to turn off their lights for 60 minutes.

The Associated Press reports that hundreds of landmarks around the world, including New York's Empire State Building, Big Ben in London, the Great Wall of China and Tokyo Tower, will all go dark for an hour.

It only makes sense that Sydney would be one of the first to celebrate the darkness, since Earth Hour began in the Australian capital in 2007, when the World Wildlife Fund inspired residents to show their commitment to the planet. As the organization's Web site states: "There's more to it than switching off lights for one hour once a year. It's about giving people a voice and working together to create a better future for our planet."

Earth Hour co-founder Todd Sampson, chief executive of advertising firm Leo Burnett Sydney told AFP, "We never would have predicted that it would be as big as it is now. And it is even bigger overseas than it is locally.

"It's not designed, and it would be foolhardy to believe, that switching a light switch is going to save the planet," he told reporters near the Sydney Harbor Bridge on Saturday. "It was originally done to raise awareness, to get people to think about it and then take action in many different ways. I think skepticism is part of the debate. It moves everything forward."

See more images from Earth Hour

WWF said the number of countries and territories participating has grown to 147, up from 135 last year. The organization holds the event annually on the last weekend in March because it's about "the time of the spring and fall equinoxes in the northern and southern hemispheres respectively. This allows for near coincidental sunset times in both hemispheres, thereby ensuring the greatest visual impact for a global 'lights out' event," says the WWF Web site.

In the United States, five states are participating — Illinois, Maine, Minnesota, Montana and New Hampshire -- and almost 60 cities and towns not to mention many more landmarks, buildings, colleges, businesses, and organizations.

The rest of the world is acting in a similar fashion. New Zealand got a two-hour head start of Australia, as lights were turned off at Sky Tower in Auckland and parliament buildings in Wellington. Several buildings along Victoria Harbour in Hong Kong participated, including the International Finance Centre, the second tallest building in the city.

And some observers will be out of this world. Space.com reported that "one of the astronauts living on the International Space Station will be the first to observe the event from onboard the orbiting outpost. Dutch astronaut André Kuipers will keep watch over the planet from the space station's orbital perch 240 miles (386 kilometers) above the Earth's surface, according to officials at the European Space Agency (ESA)."

"There is no better way to raise awareness for the future of the most beautiful planet in the universe," Kuipers said in a statement. "Working to understand our planet is what ESA does every day, and taking part in Earth Hour enables people to join us in this commitment."

[Related: Space: The latest frontier for Earth Hour ]

Kuipers is sharing his photos and providing commentary of Earth from space, his official blog and on Twitter @Astro_Andre.

Elsewhere, the Savoy hotel in London will use candlelight for an hour to light its front hall, bars and restaurants. In Berlin, the Brandenburg Gate will go dark, lit only by 5,000 blue and green candles in the form of a globe, courtesy of WWF members.

Among those taking part for the first time are Libya, Algeria, Bhutan and French Guinea.

"Earth Hour 2012 is a celebration of people power," WWF official Dermot O'Gorman told reporters, including AP, hours before the event in Sydney. "(It's) the world's largest mass event in support of the planet."