The United Nations officially recognized Earth Day as International Mother Earth Day in 2009.
The UN General Assembly adopted Resolution 63/278 on April 22, 2009. The resolution designated April 22 as International Mother Earth Day and invited UN bodies, governments, civil society, and other organizations to observe the date and raise environmental awareness.
The wording reflects a broader idea than a purely U.S. environmental anniversary. “Mother Earth” connects ecological protection with the understanding that human societies depend on functioning natural systems for food, water, health, and livelihoods. The resolution also linked the observance to sustainable development and harmony with nature.
The designation did not create Earth Day itself: the first widely recognized Earth Day took place in the United States in 1970. Instead, the 2009 UN action gave the date an official international designation and helped frame April 22 as a global observance.