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Julian calendar
The calendar introduced by Julius Caesar in 46 B.C. to replace the lunar calendar. The Julian calendar provided for a year of 365 days with a leap year every four years, or an average year length of 365.25 days. Because the solar year is slightly shorter, the Julian calendar gradually moved out of phase with the seasons and was superseded by the Gregorian calendar, introduced by Pope Gregory XIII.
Julian date
A Julian date is expressed as the number of days elapsed since January 1, 4713 B.C. For example, the date October 9, 1995 (Gregorian calendar) would be expressed as 2,450,000 on the Julian calendar. Julian dates are useful for finding elapsed times between events that may be many years apart, as in astronomy. |
