Earth Day
"... the only home we've ever known." - Carl Sagan. Image credit: MarcelClemens (using elements furnished by NASA)/Shutterstock.com.
Date: April, 22nd.
Observed: globally.
Origin: environmental movement in 1970.
Purpose: demonstrate support for environmental protection.
Reference:
http://www.earthday.org/about/the-history-of-earth-day/