Religious Affairs Office

It would seem that the ancient peoples of the Italian Peninsula mainly used lunar calendars. However, we know that shortly after the foundation of Rome (8th century BC), the solar calendar was adopted. A few centuries later, this calendar was modified by Julius Caesar (1st  century BC) and became known as the Julian calendar. The most significant change was that the start of the year moved from March to January. Gener in Catalan and January in English come from the Latin ianuarius, for Janus, the god of beginnings and transitions in Roman mythology, with a clear reference to the opening or start of the year.

In the year 1582, Pope Gregory XIII made changes to the Julian calendar, which came to be known as the Gregorian calendar and became the institutional calendar of the Catholic church and the most widely used calendar in the world.

In her book Salamanca y la medida del tiempo [Salamanca and the measurement of time] (Universidad de Salamanca, 2012), professor Ana María Carabias Torres argues that a group of scholars from the University of Salamanca were the ones to demand and promote the reform of the Julian calendar at the start of the 16th century , based on the Alfonsine Tables (13th century), which in turn were based on the Toledan Tables (11th century). The reform of the Julian calendar was mainly for liturgical reasons, that is, to ensure Christian celebrations and holidays were held on a specific, more precise date, particularly for Easter, based on the spring equinox. This need for an adjustment could was already noted at the First Council of Nicaea (4th century).

 

DESCRIPTION OF THE CALENDAR

Like the Julian calendar, the origins of the Gregorian calendar are associated with the birth of Christ, the start of the Christian era. Both calendars have 365 days, to which an additional day is added approximately every four years, the so-called bissextile years, or leap years.

The main differences between the way the Julian and Gregorian calendars are calculated are that the Gregorian calendar is a few minutes shorter than the Julian calendar and that, in the year it was established, the Gregorian calendar lost 10 days compared to the Julian calendar. In addition to these differences, the two calendars also have notable liturgical differences: the Julian calendar is followed by a large number of Orthodox churches and the Gregorian calendar is followed by all Catholic churches and most Protestant churches that emerged from the Lutheran Reformation.

The Gregorian calendar is made up of twelve solar months, that is, the period of days that, theoretically, it takes the Sun to pass through each of the twelve zodiac constellations of the ecliptic. The names of the months of the Gregorian calendar also follow the Latin tradition of the Julian calendar, with a mix of names that refer to gods or planets (January, February, March, April, May, June), Roman emperors (July and August) and numbers (September, October, November, December). The months have between 30 and 31 days, except for February, which has 28 days (29 in a leap year).

The week (septimana, setmana in Catalan) groups a cycle of seven days related to the seven planets known in antiquity, all of which are clearly identifiable, except for Sunday in Catalan (diumenge), which originally referred to the Sun (dies Solis) and was later considered to be the “Day of the Lord” (dies Dominicus). With regard to Saturday (dissabte in Catalan), two possible explanations are proposed: “Saturn Day” (dies Saturni) or a reference to the Hebrew shabbat.