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U2 Play Sydney Leg Of Their Vertigo Tour

SYDNEY, AUSTRALIA - NOVEMBER 10: (UK TABLOID NEWSPAPERS OUT. EXCLUSIVE) (L-R) Adam Clayton, Larry Mullen Jr, The Edge and Bono of U2 walk to the stage ahead of their concert at the first of three rescheduled Sydney dates on their Vertigo Tour, at the Telstra Stadium on November 10, 2006 in Sydney, Australia. U2 have toured Australia four times in 1984, 1989, 1993 and 1998. The Vertigo 2005 Tour covered Europe and North America, with The Vertigo 2006 Tour taking in Mexico, South America, New Zealand Japan and Australia. The band has released 14 albums, selling 120 million worldwide. (Photo by Dave Hogan/Getty Images)

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.