At 8:30 p.m. EST on Saturday, March 29 millions across the globe will participate in Earth Hour by switching off their lights for one hour to raise awareness about the impact of energy use on climate change.

The annual event began as a simple idea and eventually launched into a global phenomenon that attracts over a billion participants around the world. Participants celebrating the eighth edition of Earth Hour will also show their support for a range of environmental issues like deforestation and energy efficiency.

"Earth Hour is more than just this hour. Uniting behind a common purpose demonstrates that we can make a meaningful difference. Earth Hour is our chance to make our commitment to protecting our planet not just for one hour a year, but every day," states EarthHour.org.

In addition to people turning off their lights in their homes and offices, a number of famous landmarks will also make the switch, including the Eiffel Tower in Paris, Houses of the British Parliament, Buckingham Palace, Tower Bridge and the London Eye in Britain, the Empire State Building in New York, the Kremlin and Red Square in Moscow, Burj Khalifa in Dubai and the Brandenburg Gate in Berlin, reports India Today.

"For us the symbolism of turning your lights off will always be important. But the big thing for us has always been how to push it beyond the hour," said Earth Hour's CEO and co-founder, Andy Ridley.

"The stage we're at now is to make it really easy for people from their handset, tablet or laptop to be able to do something pretty immediate to make a difference. That's the holy grail for us - building a global collective movement, far beyond the event, where the event becomes a kind of inspiration but the movement is really the essence of it."

Since it launched in 2007 in Australia, Earth Hour has become the world's biggest environmental event. Last year, more than 7,000 towns and cities in 154 countries were part of the event.

Still, some critics of Earth Hour say it's nothing more than a feel-good event that does little for reduce CO2 emissions and trivializes the enormity of climate change.

"While more than a billion people participate by shutting off their lights for an hour - and saving at most the equivalent of China halting its CO2 emissions for fewer than four minutes - 1.3 billion people across the developing world will continue to live without electricity as they do every other night of the year," writes Bjorn Lomborg.