Why 1972 Was the Longest Year in History

While the pandemic made 2020 seem like the longest year in history, that title belongs to 1972. Officially the longest year in history, it got the title because of a whole two seconds. That’s because two extra seconds were leap seconds that were added on June 30 and again on December 31 in the same year. From time to time, leap seconds are added to clocks on earth to accurately reflect the observed solar time. This is due to the fact that the earth’s rotation around the axis and its revolution around the sun is imprecise and varies from year to year. By adding an extra second to the time count, we effectively stop our clocks for that second to give earth the opportunity to catch up. On average, a leap second is inserted about every 21 months, but because the Earth's rotation speed varies in response to climatic and geological events, leap seconds are irregularly spaced and unpredictable. As of today, there have been 27 leap seconds applied, the most recent on December 31, 2016. Don’t get too concerned about the extra time. Scientists predict that it will take over 700 years before the clock says 11:30 when it would say 12:00. That gives us plenty of time to prepare for some other way to put the world’s clocks and computers back in sync with the earth’s rotation.