Early Easter

You may have noticed that Easter comes early this year. In fact, this is earliest Easter Sunday for the next 152 years.

For Western churches (Roman Catholic and Protestant denominations) Easter is the first Sunday after the first calculated full moon following the Spring Equinox. Easter can occur anytime between 22 March and 25 April, a total of 35 days - 28 days for the lunar cycle plus 7 days in a week.

The current method for determining Easter was established by Pope Gregory XIII in 1582. For purposes of calculating Easter, the Spring Equinox is fixed as 21 March. The 'full moon' is determined by prescribed calculations rather than actual astronomical observation. The calculated 'full moon' can vary from the actual full moon by as much two days.

Eastern Orthodox churches follow a different set of calculations based upon the Julian rather than the Gregorian calendar. Meanwhile, Passover is based upon the Jewish lunar calendar. Occasionally, Eastern Orthodox Easter and Passover will coincide with the same weekend as Easter but, generally they do not.

Easter was last celebrated on the earliest date 22 March back in 1818; this will not occur again until 2285. Easter won't be celebrated again on 23 March until 2160. The cycle for Easter dates repeats every 5.7 million years, with 19 April being the most common date.

For more information, go to the Wikipedia and US Naval Observatory websites. Click here to view the rather involved formulas used to calculate Easter.