VATICAN CITY, JAN 9 (ZENIT).- When exactly does the third millennium begin? Has it already started or will it start on January 1, 2001? This debate has surfaced cyclically at the end of every century since 1599, and prestigious astronomers have made statements on the issue in the course of history.

Interestingly enough, the Catholic Church itself has made a statement on the matter. On November 13, 1889, Pope Leo XIII wrote that the 19th century ended at midnight on December 31, 1900. The pontifical text clarified that, although the century began in 1901, the Jubilee year would be celebrated in 1900.

Several of John Paul II's documents confirm this calculation. It is reflected in paragraph 50 of the encyclical "Dominum et Vivificantem," and in numbers 18, 23, 44 and others of the apostolic letter, "Tertio Millennium Adveniente," written in 1994.

Given the above, John Paul II has decided to increase the temporal extension of the Jubilee of 2000. Indeed, like others in the past, it began on Christmas Eve, 1999, but it will end on January 6, 2001, thus embracing the forthcoming century, as this Holy Year is meant to be a bridge between the second and third millennium. The Holy Year's official calendar establishes the passage to the third millennium on December 31, 2000.

Back in December 1899, astronomer Camilo Fammarion published a lengthy article on the argument to demonstrate, with an elementary calculation, that the 20th century would begin on January 1, 1901. But he himself said that in the year 2000 the same debate would reemerge. "Our great grandchildren will ask the same question in the newspapers at the end of the century... And there will be those who will renew the secular confusion."

The fundamental reason is that every century begins with the year 1 and ends with 100, 200, etc., since there is no year 0.