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Sir Richard Branson, Daryl Hannah and GA President Srgjan Kerim hold a press conference on Climate Change Challenges - February 11, 2008

NEW YORK - FEBRUARY 11: Music Mogul Sir Richard Branson speaks at a press conference at the United Nations in which he called upon the 20 wealthiest nations in the world to match his $25 million Earth challenge while also calling for the formation of an environmental war room on February 11, 2008 in New York City (Photo by Jemal Countess/WireImage)

Earth Day: Stars and Their Environmental Causes

We're celebrating Earth Day by taking a look at stars who are taking an active role in protecting our planet with their charitable work.