The Julian calendar officially began on Jan. 1 in 45 BCE. This method would continue over several centuries, but not without issue. Caesar's math of 365.25 days was close, but it wasn't the exact ...

Like the Gregorian calendar, the Julian calendar has 12 months and 365 days "with each fourth year having 366 days and the months each having 31 or 30 days except for February which has 28 or in ...

The Julian calendar worked so well at first that many countries adopted it. Unfortunately, it was flawed, being 0.0078 of a day (about 11 minutes and 14 seconds) longer than the tropical year.

While under the Julian calendar, a day shift accumulated every 129 years, that only happens every 3,333 years under the modern calendar. But that’s a problem for another millennium.

When the Julian calendar was later refined into the Gregorian calendar in 1582, the tradition of adding a leap day to February persisted. Contributing: Saman Shafiq, USA TODAY.

In honor of Leap Day, this read is for the history nerds. Ever wonder how America caught our calendar up with the rest of the world? In September 1752, we skipped over 11 days.

What it boiled down to was that Sweden resynchronized itself with the old Julian calendar by adding an extra leap day, Feb. 30, to 1712. Easter Sunday was restored to its proper day.

The Julian calendar was used in the West until 1582, when the Gregorian calendar was adopted. The Julian calendar's method of calculating Easter was standardized in the year 325 at the First ...

The old calendar had been 365.25 days long; the new calendar was 365.2425 days long. The new calendar also shifted the dates, which had drifted by about two weeks, back in sync with seasonal shifts.

In the Julian calendar, the new year began on March 25. So March 24, 1701 would be followed directly by March 25, 1702. The Gregorian calendar, as we know today, begins on January 1. ...