Earth Day, an international holiday to educate and raise awareness about environmental issues, is held on April 22 each year. Wikimedia Commons

Earth Day, an international holiday designed to educate and raise awareness about environmental issues, is held on April 22 each year.

The day began in the United States thanks to a U.S. senator that was inspired by the antiwar protests during the 1960s. Senator Gaylord Nelson decided to create Earth Day in 1970 to spawn a mass environmental movement. Today, Earth Day is run by the Earth Day Network, a group created by the organizers of the first Earth Day that promotes year-round environmental action. This year will be the 44th anniversary of the environmental holiday.

For those unfamiliar with the “green” holiday below are 10 facts to share on Earth Day.

1. Earth Day began as a “national teach-in on the environment” to spread environmental education on university campuses. The idea stemmed from newfound knowledge of the dangerous effects of pollution outline in Rachel Carson’s 1962 bestseller “Silent Spring” and a 1969 fire on the Cuyahoga River in Cleveland, Ohio, shed light on the problem of chemical waste disposal.

2. U.S. Senator Gaylord Nelson announced Earth Day in the fall of 1969 during a conference in Seattle. “The response was electric,” Nelson wrote in a post for New York State’s Department of Environmental Conservation. “It took off like gangbusters. Telegrams, letters, and telephone inquiries poured in from all across the country. The American people finally had a forum to express its concern about what was happening to the land, rivers, lakes, and air - and they did so with spectacular exuberance.”

3. Nelson was awarded the Presidential Medal of Freedom for his role as founder of Earth Day. Along with Harvard student Denis Hayes, founded the Earth Day Network.

4. More than 20 million people participated in the first Earth Day.

5. Earth Day had its share of critics. A Milwaukee corporation president refused to donate to Earth Day because he detected the involvement of "certain militants" interested in "the total overthrow of the business community." Anti-Vietnam War protestors felt the day would displace efforts they were organizing on college campuses. Even some who endorsed Earth Day had their doubts. A mayor from Gary, Indiana was worried Earth Day would "distract the nation from the human problems of the black and brown American."

6. Earth Day was renamed officially by the UN in 2009 as International Mother Earth Day.

7. On Earth Day 2012, more than 100,000 people rode bikes in China to reduce carbon dioxide emissions and save fuel.8

8. While some speculated April 22 was chosen as Earth day to commemorate the birthday of Soviet Union founder, Vladimir Lenin, the day was chosen because it fell on a Wednesday, a good day to host large environmental rallies.

9. Today Earth Day is celebrated by more than one billion people in 190 nations.

10. The theme for Earth Day 2014 is Green Cities with the goal of creating sustainable communities around the world.