You can be part of a global movement of a billion people, and it's a lot easier to join than the Catholic Church. All you have to do is turn off your lights for an hour on Saturday night.

This year marks the third annual Earth Hour. On Saturday (March 28), people all around the world will be turning their lights off at 8:30 p.m. local time. The movement started in 2007 when the people of Sydney, Australia band together to turn off their city. Last year it went global with an estimated 50 million people participating. This year organizers are aiming for 1 billion participants.

I don't know if that's possible, but they already have nearly 3,000 cities and more than 36,000 businesses, schools, and organizations, including U.N. facilities, signed up. The goal is to send a message to international leaders meeting in Copenhagen this year that the world wants action on climate change.

It'll be amazing to see the darkening of landmarks from the pyramids of Giza and the acropolis in Greece to modern marvels such as China's Bird Nest Stadium and Water Cube or our very own Golden Gate Bridge and Empire State building.

This hour could be an interesting personal and spiritual challenge as well. The website suggests a variety of activities to do in the dark, but what if that hour included prayer? We Catholics know how a darkened, candlelit church can set a prayerful mood. What if we gathered in churches to be together as a community during Earth Hour?

This being a movement fueled by the Internet and directed at those of us who are constantly plugged in, it'd also be good to remember those who live off the grid in developing countries as we fast from electricity. Really, one hour isn't bad. I spent a summer in Honduras without electricity, but even then I got to come home to my electronics.  

Will you participate? If you do, let us know how it goes.