Catholics can celebrate “leap day” as a uniquely Catholic holiday because of a saint — Oswald — and the fact that the idea of a leap year is a Catholic one.
The pagan Julian calendar, named after Julius Caesar, began in 45 B.C., and from its start, it was out of sync with the progression of the stars and seasons. So a new calendar with a leap day was proposed.
In 1582, Pope Gregory XIII mandated a reform to the calendar — after the Church’s astronomers determined that one year was actually 365.2425 days. He also amended the rule for determining a leap year by defining it as a year that was divisible by 100 as long as it was also divisible by 400. Thus, 2012 is a leap year, as was 2000,...READ MORE