The original Roman calendar divided the year from March to December into 10 months of either 29 or 31 days, based on lunar ...

Pope Francis reaffirms Catholic Church's willingness to accept a common date for Easter in the West and East, highlighting ...

At least, that was the idea. Revolutionary as the Julian calendar was, it wasn't perfect, and fell out of alignment over time. In 1582, Pope Gregory XIII introduced the Gregorian calendar ...

The Julian calendar, which was less astronomically precise, gradually fell out of alignment with the solar year. By the 16th century, this discrepancy had become significant enough for Pope ...

Prior to the Gregorian and even Julian calendars, Roman King Numa Pompilius (715-673 BC) set about creating a calendar with equal-length months, the University of Chicago said. "When Numa ...