April 22, 1993, marked the release of the 'Lunar Prospector' spacecraft, which aimed to map the moon's surface and search for water ice at the lunar poles.

On April 22, 1972, the first Earth Day was officially celebrated internationally, with over 20 million people participating in events across the United States.

The first Earth Day was celebrated on April 22, 1970, marking the beginning of the modern environmental movement and leading to the establishment of the U.S. Environmental Protection Agency.