The PASCHAL FULL MOON takes place on APRIL19 at 11h 13 Universal Time (Add ONE HOUR for BST).The illustration shows the Paschal Full Moon rising on FRIDAY APRIL 19th,
which, this year, is GOOD FRIDAY

The Paschal Moon. - Fr. Richard Smith

The date of Easter is determined by the Paschal Full Moon, which is the Sunday, following the first Full Moon, after the Vernal Equinox, the beginning of Spring, in the Northern Hemisphere. The extreme limits of the Paschal Full Moon are 21st March and 25th April. This variation explains why we speak of an 'early' or late' Easter.

Despite the apparent simplicity of dating Easter, it has been the cause of considerable controversy. Unlike Christmas, Easter is a 'moveable feast' which is dependent upon the lunar calendar. There have been repeated moves to 'fix' the date of Easter, so far without success.

The 'Paschal Controversies' during the first centuries of the Church were largely concerned with different methods of computation. Originally, local churches had the responsibility of working out the date of Easter for themselves. This led to considerable variations.

One local method, 'Quatrodecimanism', relied on the date of the Jewish Passover - 14th/15th Nisan. Because the Jewish calendar follows the lunar cycle, Nisan corresponds to March/April. The Passover is celebrated on 14th/15th Nisan, whichever day of the week it is. This group of Jewish converts to Christianity thought that Easter - the Christian Passover - should also be celebrated on 14th Nisan, whether it was a Sunday or not. Their nick-name comes from the Latin word for fourteen, 'quattuordecim'.

The 'Quatrodecimans' tried to get their approach adopted throughout the Church. They were unsuccessful, but 'Quatrodecimanism' survived in Asia Minor until the fifth century.

The Church used two main methods of computation - the 'Antiochene' and the 'Alexandrian'. Unfortunately, these methods arrived at different dates for the Paschal Full Moon. The more astronomically based 'Alexandrian Method' always placed Easter after the Vernal Equinox. This was accepted as the universal practice of the Church at the Council of Niccea in 325.

A further divergence appeared with the introduction of the 'Roman Method'. This used a different Paschal Cycle, whereby Easter was never observed before 16th April. The 'Alexandrians'used an older, Anatolian Paschal Cycle.

The use of the two systems led to conflict. Provinces following the 'Alexandrian Method' observed Easter in the middle of March, whereas the 'Roman' provinces kept the feast in Aprilr Eventually, Rome adopted the more accurate 'Alexandrian Method'.

After St. Augustine landed in Kent in 597, there were two Christian missions in Britain - one Roman, led by Augustine, the other Celtic. These two missions came into contact with each other in the Kingdom of Northumbria and their differences soon became apparent.

The two missions had their own method for computing the date of Easter. Celtic Christians could be celebrating Easter, when Latin Christians were still observing the penitential season of Lent. The Synod of Whitby was convened in 664 to resolve the confusing situation. When it came to dating Easter, the Synod favoured the "Alexandrian Method', now used by Rome.

This year the Paschal Full Moon is on Friday 19th April (Good Friday). In the Western Church, Easter Day is Sunday 21st April. The Eastern Orthodox Christians still use the Julian Calendar and so the 'Orthodox Easter' will be a week later. The ecumenical rapprochement between East and West has included discussions about a 'common' date for Easter.
So far, these discussions have not borne fruit.