Just what is this Earth Day thing, anyway? This Saturday marks the event's 36th anniversary, and with more people growing concerned about climate change, Earth Day 2006 is poised to be a big one. Earth Day celebrates the birth of the environmental movement - a day when people around the country came out to rally for cleaner air and water, conservation of land and wildlife, and more sustainable use of resources. The original Earth Day was bipartisan, and was followed by the passing of several of our most important federal environmental laws.

Looking for a way to get in on the Earth Day action? The EarthDay Network features a handy tool that lets you search for events by country, state, city, even zip code. The web site also offers a useful list of 10 things you can do right now to help reduce greenhouse gas emissions: change your lightbulbs, change your driving habits, change the energy efficiency of your home.

For more Earth Day events and activities, EnviroLink also offers a list of events, from hikes to clean-ups to expos. For more info on outdoor activities in your area, Trails.com lists things from bird watching to sea kayaking.

Every city around the country seems to have something planned for this Saturday. If you're in New York City, check Earth Day New York. In Oakland, go to Keep Oakland Beautiful for Earth Day events. Want to see what's up in Minneapolis? Visit the Park and Recreation Board web site for listings.

For inspiration on why to care at all about Earth Day, take a look at the planet via the Earth and Moon Viewer, which lets you view up-to-the-minute snapshots of the blue planet from just about every satellite in the sky.

Image credit: Minneapolis Park and Recreation Board