Ecclesiastical new moon
Encyclopedia
An ecclesiastical new moon is the first day of a lunar month (an ecclesiastical moon) in an ecclesiastical lunar calendar
. Such months have a whole number of days, 29 or 30, whereas true synodic months can vary from about 29.27 to 29.83 days in length. Medieval authors equated the ecclesiastical new moon with a new crescent moon, but it is not a phase of the true moon. If the ecclesiastical lunar calendar is accurate, the ecclesiastical new moon can be any day from the day of the astronomical new moon
or dark moon
to two days later (see table).
The ecclesiastical new moon which falls on or next after March 8 is of special importance, since it is the paschal new moon that begins the paschal lunar month (see table). The fourteenth day of the same lunar month is the first of the calendar year to occur on or next after March 21. This fourteenth day was called the paschal full moon
by medieval computists. Easter
is the following Sunday.
Calendar pages in medieval liturgical books indicated the ecclesiastical new moons by writing the Golden Number
to the left of the day of the month on which the ecclesiastical new moon would occur in the year of that Golden Number. In some places the age of the moon was announced daily in the office of Prime
at the reading of the martyrology
.
When in the 13th century Roger Bacon
complained about the discrepancy between the ecclesiastical moon and the observed lunar phases, he specifically mentioned the discrepancy involving the ecclesiastical new moon
These complaints were finally addressed by the construction of the Gregorian calendar
.
Computus
Computus is the calculation of the date of Easter in the Christian calendar. The name has been used for this procedure since the early Middle Ages, as it was one of the most important computations of the age....
. Such months have a whole number of days, 29 or 30, whereas true synodic months can vary from about 29.27 to 29.83 days in length. Medieval authors equated the ecclesiastical new moon with a new crescent moon, but it is not a phase of the true moon. If the ecclesiastical lunar calendar is accurate, the ecclesiastical new moon can be any day from the day of the astronomical new moon
New moon
In astronomical terminology, the new moon is the lunar phase that occurs when the Moon, in its monthly orbital motion around Earth, lies between Earth and the Sun, and is therefore in conjunction with the Sun as seen from Earth...
or dark moon
Dark moon
A dark moon describes the Moon during that time that it is invisible against the backdrop of the Sun in the sky. The duration of a dark moon is between 1.5 and 3.5 days, depending on the orientation of the Earth and Sun....
to two days later (see table).
The ecclesiastical new moon which falls on or next after March 8 is of special importance, since it is the paschal new moon that begins the paschal lunar month (see table). The fourteenth day of the same lunar month is the first of the calendar year to occur on or next after March 21. This fourteenth day was called the paschal full moon
Paschal Full Moon
Notionally, the paschal full moon refers to the ecclesiastical full moon of the northern spring used in the determination of the date of Easter. The name "paschal" is derived from "Pascha", a transliteration of the Greek word, which is itself a transliteration of the Hebrew pesach, both words...
by medieval computists. Easter
Easter
Easter is the central feast in the Christian liturgical year. According to the Canonical gospels, Jesus rose from the dead on the third day after his crucifixion. His resurrection is celebrated on Easter Day or Easter Sunday...
is the following Sunday.
Calendar pages in medieval liturgical books indicated the ecclesiastical new moons by writing the Golden Number
Golden numbers
A golden number is a number assigned to each year in sequence to indicate the year's position in a 19-year Metonic cycle. They are used in the computus and also in the Runic calendar. The golden number of any Julian or Gregorian calendar year can be calculated by dividing the year by 19, taking...
to the left of the day of the month on which the ecclesiastical new moon would occur in the year of that Golden Number. In some places the age of the moon was announced daily in the office of Prime
Prime (liturgy)
Prime, or the First Hour, is a fixed time of prayer of the traditional Divine Office , said at the first hour of daylight , between the morning Hour of Lauds and the 9 a.m. Hour of Terce. It is part of the Christian liturgies of Eastern Christianity, but in the Latin Rite it was suppressed by the...
at the reading of the martyrology
Roman Martyrology
The Roman Martyrology is the official martyrology of the Roman Rite of the Roman Catholic Church. It provides an extensive but not exhaustive list of the saints recognized by the Church.-History:...
.
When in the 13th century Roger Bacon
Roger Bacon
Roger Bacon, O.F.M. , also known as Doctor Mirabilis , was an English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empirical methods...
complained about the discrepancy between the ecclesiastical moon and the observed lunar phases, he specifically mentioned the discrepancy involving the ecclesiastical new moon
Quilibet computista novit quod fallit primatio per tres dies vel quatuor his temporibus; et quilibet rusticus potest in coelo hunc errorem contemplari. (Any computist knows that the prime [of the moon] is off by three or four days in our time; and any rustic can see this error in the sky.)
These complaints were finally addressed by the construction of the Gregorian calendar
Gregorian calendar
The Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...
.
| Year | Gregorian paschal new moon | Days in paschal lunar month |
|---|---|---|
| 1995 | April 1 | 29 |
| 1996 | March 21 | 29 |
| 1997 | March 10 | 29 |
| 1998 | March 29 | 29 |
| 1999 | March 18 | 29 |
| 2000 | April 5 | 30 |
| 2001 | March 26 | 29 |
| 2002 | March 15 | 29 |
| 2003 | April 3 | 29 |
| 2004 | March 23 | 29 |
| 2005 | March 12 | 29 |
| 2006 | March 31 | 29 |
| 2007 | March 20 | 29 |
| 2008 | March 9 | 29 |
| 2009 | March 28 | 29 |
| 2010 | March 17 | 29 |
| 2011 | April 4 | 30 |
| 2012 | March 25 | 29 |
| 2013 | March 14 | 29 |