It’s happening tomorrow at 8.30 PM local time, wherever you are on earth.  Turn off your lights!  That’s all.   We usually stay out of the office on Saturdays, so the lights will already be out at Firstgiving Towers, but a bunch of us will be observing Earth Hour in the privacy of our own homes.

What is Earth Hour, exactly?  It’s a virtual event sponsored by the World Wildlife Fund.  Here’s how they describe it:

This year, Earth Hour has been transformed into the world’s first global election, between Earth and global warming.

For the first time in history, people of all ages, nationalities, race and background have the opportunity to use their light switch as their vote – Switching off your lights is a vote for Earth, or leaving them on is a vote for global warming. WWF are urging the world to VOTE EARTH and reach the target of 1 billion votes, which will be presented to world leaders at the Global Climate Change Conference in Copenhagen 2009.

The remarkable thing is that Earth Hour grew from one city’s initiative in 2007 to a global event with over 50 million participants in 2008.  And this growth was fueled primarily by social media and grassroots online  networking with blogs like this one.  

If your computer has a decent battery life, you can keep in touch with the global community during Earth Hour (or just follow participants in other time zones) by blogging, tweeting, photographing and video-ing.  More information is at the Earth Hour website, here.  And check out these fundraisers who are going the extra mile to raise money for the Earth Hour’s sponsoring organization, the World Wildlife Fund.