In the margins: why does the date for Easter change every year?
This year, Easter Sunday coincides with April Fool’s Day! There’s no need to be fooled about why the Easter date changes every year though.
Easter Date Calculation
Easter Sunday is the first Sunday after the full Moon, following the March equinox (which is always on or around 22nd March every year). It’s a bit of a calculation and here it is for 2018…
In 2018, the March equinox is on the 21st March at precisely 12:15am (WA time). The full Moon after this date is on Saturday, 31st March and therefore Easter Sunday is the following Sunday which is 1 April 2018!
What is an Equinox?
An equinox is when the centre of our Sun is on exactly the same plane as Earth’s equator. The Earth’s axis isn’t tilted toward the Sun one way or the other and the hours of night and day are almost equal in length. Another thing to note at equinox is that sunrise is due east and sunset is due west.