More than 40 years after the first Earth Day, many riddles still remain when it comes to our planet.
For Earth Day, gardeners can order open-source seeds to help ensure vegetable, fruit and grain seeds are available to everyone.
To kick off Earth Day, check out a snapshot of remarkable moments from around the world.
Just in time for Earth Day, the Princeton Review has released its 2012 Guide to Green Colleges. The 232-page guide is the only free, comprehensive guide to green colleges that is updated annually.