Earth Day Celebrated By John Legend, Jack Johnson, Others

'Avatar' director James Cameron, Sting and Q-Tip are expected at Washington, D.C.'s Climate Rally.

For the past 40 years, environmentalists have considered April 22 to be a day of reckoning. Earth Day is a time to organize, lecture, clean up and generally respect the planet — and remind others to do so as well. With President Obama focused on greening the economy by finding more, and better, alternative sources of energy and encouraging Americans to upgrade their old, inefficient appliances and cars, suddenly Earth Day is back in vogue.

Coinciding with the 40th anniversary of Earth Day, Vice President Joe Biden announced this week that the administration intends to invest $452 million in Recovery Act funding to retrofit buildings in 25 communities from Wisconsin to New York as part of the White House's ambitious plans to cut down energy use and reduce America's dependence on foreign oil. (Here are some White House tips on how to green your home, work and community.)

Although communities across the country will be holding various events to commemorate the day, the biggest gathering is planned for the National Mall in Washington, D.C., on Sunday, when Sting and John Legend will be joined by the Grateful Dead's Bob Weir, Booker T. Jones, Mavis Staples, the Roots, Passion Pit, former Fall Out Boy lead singer Patrick Stump and Q-Tip for the Climate Rally. Organizers and speakers will urge Congress to pass clean-energy legislation in 2010. Also participating in the event are "Avatar" director James Cameron and civil-rights activist Jesse Jackson.

The day's actual musical event will feature a concert by Ben Harper and the Relentless7, Guster and Alberta Cross at the Verizon Wireless Amphitheater in Alpharetta, Georgia, and a gig by folk duo the Indigo Girls at the Stefanie H. Weill Center for the Performing Arts in Sheboygan, Wisconsin.

One of the greenest rock musicians, Jack Johnson, will hold his environmental benefit, the Kokua Festival 2010, at the Waikiki Shell in Honolulu on Friday and Saturday, with help from supporting acts Ziggy Marley and Taj Mahal.

Also touching down in Hawaii, at the University of Hawaii (Manoa) through Friday, is the Save My Oceans Tour, a multimedia event featuring music, film and art installations celebrating the oceans. The tour will also stop at George Washington University, the University of Utah (Salt Lake City) and University of Colorado (Boulder) through Friday and UN Berkeley through Thursday.

Earth Day was founded by the late U.S. Sen. Gaylord Nelson of Wisconsin to raise awareness about environmental issues and was first held on April 22, 1970. It has since turned into an international event that often features a week's worth of activities centered on conservation and clean-energy awareness.

How are you celebrating Earth Day? Let us know in the comments!