Earth Day is the designation of April 22 as a day to inspire awareness and appreciation for the Earth's environment. Earth day was a day founded by U.S. Senator Gaylord Nelson as an environmental teach-in held on April 22, 1970. While this first Earth Day was focused on the United States, an organization launched by Denis Hayes, who was the original national coordinator in 1970, took it international in 1990 and organized events in 141 nations. Earth Day is now coordinated globally by the Earth Day Network, and is celebrated in more than 175 countries every year. April 22 corresponds to spring (season) in the Northern Hemisphere and autumn in the Southern Hemisphere.