1. Senator Gaylord Nelson conceived Earth Day in the early 1960s. His concerns during his time as a Senator was that environmental issues were not being addressed in the political arena and even more so after he witnessed the California oil spill in 1696. He took inspiration from the Vietnam War protests, to organize a nationwide grassroots to demonstrate and to promote conservation involvement and awareness across the country.
2. The first Earth Day was in 1970. Nelson's demonstration was set for April 22, 1970 and it purposefully fell between spring break and final exams with the hope that college students would participate in the events.
3. Earth Day went global in 1990. 20 years after the Earth Day, the campaign spread internationally. The 1990 demonstration mobilzed 200 million people in 141 countries. This also gave it major attention to the environmental issues like recycling.
4. It's known as "International Mother Earth Day" around the world. The United Nations General Assembly came up with the moniker in 2009, although it never stuck in America.
5. There's an "official" Earth Day song. One of the most popular Earth Day songs is Earth Anthem, was written in 2013 by Indian poet Abhay Kumar. It has been translated in dozens of languages, including all official united Nations languages.