Earth Day is one of two observances, both held annually during spring in the northern hemisphere, and autumn in the southern hemisphere. These are intended to inspire awareness of and appreciation for the Earth's environment. The United Nations celebrates an Earth Day each year on the March equinox, a tradition which was founded by peace activist John McConnell in 1969. A second Earth Day, which was founded by U.S. Senator Gaylord Nelson as an environmental teach-in in 1970, is celebrated in many countries each year on April 22. More details here