World UFO Day is celebrated on July 02, 2017. World UFO Day is an awareness day for people to gather together and watch the skies for unidentified flying objects. In the past there were two days that were called World UFO day. July 2nd and the 24th of June. The WUFODO (World UFO Day Organization) declared July 2nd to be the official World UFO day. This was done to eliminate any confusion. Also, the original first World UFO Day was celebrated on July 2 in 2001.
June 24 is the date that aviator Kenneth Arnold reported what is generally considered to be unidentified flying object sighting in the United States, while July 2 commemorates the supposed UFO crash in the 1947 Roswell UFO Incident. The goal of the July 2 celebration is to raise awareness of the Roswell findings, and to gain support in forcing governments to "tell the truth about earthly visits from outer space aliens".
An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not readily identifiable as any known object or phenomenon by visual observation and/or use of associated instrumentation such as radar. These anomalies were referred to popularly as "flying saucers" or "flying discs" during the late 1940s and early 1950s. (With material from: Wikipedia)