December 7, 1941 (Pearl Harbor attack) defined a generation.
November 22, 1963 (assignation of J.F.K.) defined another generation.
September 11, 2001 defined this generation (terrorist attack on Twin Towers, etc.).
However, the day Jesus died for the sins of the world can and must define your eternity.
(FYI: There is good evidence that Friday, April 3, A.D. 33 at 3:00 p.m. was the exact day and time that Jesus died.)