Since the actual solar year is 11 minutes shorter than the Julian year of 365.25 days, after about 120 years, the astronomical dates of the solstices and equinoxes move back one calendar day. So to correct (approximately), we add 1 day every four years (leap year). Thus, three calendar years are 365 days long; the fourth calendar year is 366 days long. The average length of the calendar year in days now becomes: (3 x 365 + 366)/4 = 365.25 days. The Julian calendar has 1 leap year every 4 years: Every year divisible by 4 is a leap year. However, the 4-year rule was not followed in the first years after the introduction of the Julian calendar in 45 BC. Due to a counting error, every 3rd year was a leap year in the first years of this calendar’s existence. The leap years were: The first is the year in the Julian calendar, which was the calendar in use in the country. The second is the year that it would have been if the year number had changed on January 1. To avoid confusion, both years are sometimes entered into a record. This is called Double Dating or Dual Dating. Gregorian calendar, solar dating system now in general use. It was proclaimed in 1582 by Pope Gregory XIII as a reform of the Julian calendar. The Gregorian calendar differs from the Julian only in that no century year is a leap year unless it is exactly divisible by 400 (e.g., 2000). These calendars led, eventually, to the Julian calendar, introduced by Julius Caesar, which approximated the year at 365.25 days, fairly close to the actual value of 365.2422. The Romans achieved this approximation by declaring years to have 365 days each, with the exception of every fourth year. pCOYN.

year in julian calendar