This Saturday, don't surprised or alarmed if your city, neighborhood or street suddenly goes dark for an hour, starting at 8.30pm, local time. It is not because of a natural disaster nor is it because these people haven't paid their electricity bills - They are simply joining the millions of people to celebrate Earth Hour, by turning off their lights and other electrical devices for 60 minutes.

Now in its fifth year, Earth Hour, the brainchild of the Australian chapter of the World Wildlife Fund, was first observed in 2007, by 2.2 million households and 2,100 businesses in Sydney, Australia. It gained popularity after it was revealed that this small 'sacrifice' resulted in conserving 10% of the electricity consumed by the city in a normal hour - the equivalent of saving the amount of carbon dioxide emitted by 48,000 cars in 60 minutes.

The idea resonated with so many people across the globe, that in 2008, over 50 million people joined in, while last year, the number increased to over one billion. Earth Hour is now the largest voluntary event in history, one that is even observed by famous city landmarks like San Francisco's Golden Gate Bridge, France's Eiffel Tower and Sydney's Opera House.

This year, the organizers are challenging people to go 'Beyond the Hour', by making a bigger change in their life than just flipping the switch for an hour, once a year, so that we can help reverse global warming, more effectively.

Are you up for the challenge? Can you set aside your television and electronic gadgets for an hour, not just tomorrow, but every single day this year? If so, be sure to sign up at www.earthhour.org. And, don't forget to spread the word around so that everyone can do his or her share in saving our planet - One light bulb at a time!

Resources: Earthhour.org.