A calendar notation in which the date is represented by one number. For example, the Julian date for December 11, 1942 is 2430705; while December 12, 1942 is 2430706. The Julian date is widely ...

4 Leap years were introduced by the Roman emperor Julius Caesar, who created a new calendar to take the extra quarter-days into account. The Julian calendar ... the exact date on which this ...

The origin of the leap year, which adds one day—the 29th—to the end of February once every four years, dates all the way back ...