Happy 44th Earth Day!

April 22 is Earth Day, and the US Environmental Protection Agency is encouraging social media interaction with an #actonclimate hashtag to identify what people are doing to address sustainability.

Google has a series of animated Doodles for Earth Day, showing a hummingbird and two flowers (or other animals). It's also promoting the hashtag #MyBeautifulEarth for sharing photos of our planet.

National Geographic recounts the history of Earth Day here, noting that an estimated one billion people worldwide will mark the day today. In 1970, Earth Day began as a "teach in" protest, and by the end of that year, the EPA had been established to work toward environmental protection.

Today's school children have grown up with the idea of social responsibility through environmental protection. Let's think green every day, not just on April 22.