Tomorrow night the Holy Father begins the Advent season by celebrating Vespers in Saint Peter's Basilica. The booklet may be found here.
He (we, Lord willing, as I plan to attend the Vespers), will sing the same exact hymn as many American parishes, Creator Alme Siderum, translated as Creator of the Stars of Night.
The celebration will conclude with the Marian Advent hymn, Alma Redemptoris Mater, which will likewise be sung around the world throughout this holy time of waiting, when we look to our Blessed Mother, our Star of the Sea.
The chants of the Church, while beautiful and eminently suitable for many musical reasons, are also helpful for a simple sociological reason: we share them with others throughout the world.