The Calendar is Named After The Pope
By Chad Upton | Editor
Many different calendar systems exist, but the calendar used by most modern cultures is known as the Gregorian Calendar.
He introduced it in 1582 and it was quickly adopted by a handful of countries. Most others jumped on the wagon over the following centuries. It was very similar to the Julian calendar, although it more accurately represented the lunar cycle and made the dates of Easter easier to calculate. This is the main reason it was preferred by Christians. The calendar is Christian centric in other ways too, after all, the years we count are relative to the traditional Incarnation of Jesus.
Interestingly, there are exactly 14 possible calendar configurations. That makes it easy to figure out if your birthday is on the weekend this year.