Yuri's Night is an international celebration held every April 12 to commemorate milestones in space exploration.Yuri's Night is named for the first human to launch into space, Yuri Gagarin, who flew the Vostok 1 spaceship on April 12, 1961. The launch of STS-1, the first Space Shuttle mission, is also honored, as it was launched 20 years to the day of Vostok 1 on April 12, 1981. In 2013, Yuri's Night was celebrated at over 350 events in 57 countries. Yuri's Night is often called the "World Space Party".