A festival celebrating the environment includes exhibits, live music, a performance by Tucson Arts Brigade and hands-on activities for all ages, from 9 a.m. to 2 p.m., Saturday, April 21; free. An all-species procession takes place at 10 a.m.; participants make banners about the importance of the species they represent and how they are affected by changes in the environment. Arizona Greyhound Rescue presents "Greyhound Buses," a parade entry encouraging public transportation to reduce emissions. Winners are announced at 11:30 a.m. Solar exhibits include model solar-electric cars and houses, designed and built from kits by middle-school students. An alternative-fuel vehicle show features biodiesel, compressed natural gas, electric, ethanol, propane and waste vegetable oil. Additional Earth Day activities take place at the zoo, where admission is free to everyone who rides their bikes. Visit tucsonearthday.org
for more information.