1972

Year 1972 (MCMLXXII) was a leap year starting on Saturday (link will display the full calendar) of the Gregorian calendar. Within the context of Coordinated Universal Time (UTC) it was the longest year ever, as two leap seconds were added during this 366-day year, an event which has not since been repeated. (If its begin and end are defined using mean solar time (the legal time scale) then its duration was 31622401.141 seconds of Terrestrial Time (or Ephemeris Time), which is slightly shorter than 1908).