The first Earth Day was celebrated on April 22, 1970. Originally the brainchild of Senator Gaylord Nelson of Wisconsin, the movement has expanded worldwide over the intervening decades, becoming the largest secular observance on the planet.

Today, Earth Day is observed by more than a billion people as a day of action to change policies and behaviors affecting human impact on the environment.

You can find out more, including how you can take action, at https://www.earthday.org/.