The Church calendar is also called the “Liturgical Calendar.”
A new Liturgical calendar was promulgated January 1, 1970, and in 1972 the U.S. Bishops ordered the new calendar into effect with the introduction of the Sacramentary in 1974.
Within the cycle of a year, Holy Mother Church unfolds the whole mystery of Christ, not only from His Incarnation and birth until His Ascension, but also as reflected in the day of Pentecost, and the expectation of a blessed, hoped-for return of the Lord.
In celebrating this annual cycle of Christ’s mysteries, Holy Church honors with special love the Blessed Virgin Mary, Mother of God, who is joined by an inseparable bond to the saving work of her Son.
A liturgical day runs from midnight to midnight, but the observance of Sunday and of solemnities begins with the evening of the preceding day. Celebration of the Eucharist, with the fulfillment of the Sunday or holy day obligation, may be on the evening before.
The liturgical season of Advent begins the Church year. (7:52)