Why do leap years exist and when is the next one?
Nearly every four years an extra day has to be added to the calendar year otherwise it would get out of sync with the Earth’s orbit around the Sun.
Nearly every four years an extra day has to be added to the calendar year otherwise it would get out of sync with the Earth’s orbit around the Sun. While a normal year is 365 days, it takes slightly longer for the Earth to make it full circle around our star, 365.242 to be exact. Over time, this discrepancy would cause the calendar to drift out of sync with the seasons, leading to inaccuracies in the timing of events.
The problem has dogged mankind basically ever since calendars were invented based on the the lunar cycle and Sun, but it wasn’t until Julius Cesear that the Leap Year as we know it more or less was systematically established. That system was given a little tweak a little over four hundred years ago but the Leap Day concept, or the periodically added extra day in the calendar, was maintained.
This additional day, 29 February, helps to compensate for the extra fraction of a day in the Earth’s orbit. By doing so, leap years ensure that our calendar year aligns more closely with the solar year.
Working out when leap years fall
2024 is a Leap Year and according to the rules that govern them the following will be 2028. The rules for determining leap years are as follows:
- Every year that is evenly divisible by 4 is a leap year, except:
- Years that are evenly divisible by 100 are not leap years, unless:
- The year is also evenly divisible by 400, in which case it is a leap year.
- Years that are evenly divisible by 100 are not leap years, unless:
Based on these rules, most years that are evenly divisible by 4 are leap years, except for years that are multiples of 100 but not multiples of 400. For example, the year 1900 was not a leap year, but the year 2000 was. 2100, 2200 and 2300 will not be leap years but 2400 will be.