alicia silverstone gi Earth Day 2012: Celebrities celebrate on TwitterSunday (April 22) marks the 42nd annual celebration of Earth Day, an event meant to bring awareness to environmental causes, and the stars took to Twitter to spread their eco-minded messages.

Alicia Silverstone tweeted out a gallery of animal images from her site The Kind Life (wonder if chewing your kid’s food for him is also environmentally friendly somehow …), while celebs like comedian Doug Benson had a less earnest take on the day.

Check out some of the tweets:

Nick Lachey: “happy earth day to everyone. this is the only planet we’ve got, so we better take good care of her!! let’s all do our part. #earthday”

Kevin McHale: “Happy #earthday!! we only have 1!”

Britney Spears: “Happy Earth Day! My kids love Rainforest Cafe, therefore let’s support the rainforest!”

Marlee Matlin: “Happy Earth Day, Earth mommas and poppas, earth kiddies and earth animals. Celebrate the beautiful planet we live on and cherish it.”

Doug Benson: “In honor of Earth Day, I will not retweet any #SideBoobSunday pictures that feature plastic bottles. #SideBoobEarthDay”

How are you celebrating Earth Day?

Posted by:Jennifer Harper