Here are a couple random facts for you . . .
1. The first ever Earth Day happened in 1970 and about 20 million people participated. Today, more than one billion people throughout the world get involved every year . . . and it's considered the largest civic observance in the world.
2. It was started by a Senator from Wisconsin named Gaylord Nelson, who eventually won the Presidential Medal of Freedom award in 1995 in recognition of his work.
3. The most common way people celebrate Earth Day is by recycling, followed by planting a tree, and cleaning up a local park.
4. Nobody really knows why it's held on April 22nd. But some theories are that it was chosen so that more students would be able to participate, because it fell between spring break and final exams . . . and because it's close to Arbor Day, which is about planting and taking care of trees.
5. It has its own flag that features a blue background and a picture of the Earth taken from the Apollo 17 spacecraft on its way to the Moon.