Calendar Index

• Length of the (tropical) year in 2000 A.D.: 365 days, 5 hours, 48 minutes, 45 seconds
• Time that the year has slowed since 1 A.D.: 10 seconds
• Average decrease in the year due to a gradual slowing of the earth's rotation: ½ second per century
• Lunar Month: 29 days, 12 hours, 44 minutes, 2.9 seconds
• The eadiest known date: 4236 B.C., the founding of the Egyptian calendar Ancient Egyptian year: 365¼ days
• Early Chinese year: 354 days (lunar year) with days added at intervals to keep the Chinese lunar calendar aligned with the seasons.
• Early Greek year: 354 days, with days added
• Jewish year: 354 days, with days added
• Early l~oman year: 304 days, amended in 700 B.C. to 355 days
• The year according to Julius Caesar (the Julian calendar): 365¼ days Date Caesar changed Roman year to Julian calendar: January 1, 45 B.c. Amount of time the old l~oman calendar was misaligned with the solar year as designated by Caesar: 80 days
• Total length of 45 B.C., known as the "Year of Confusion," after adding 80 days: 445 days
• The year as amended by Pope Gregory XIII (the Gregorian calendar): 365 days, 5 hours, 48 minutes, 20 seconds
• Date Pope Gregory reformed the calendar: 1582
• Length of time the Julian calendar overestimates the solar year per year, as determined by Pope Gregory: 11 minutes, 14 seconds
• Number of days Pope Gregory removed to correct the calendar's drift: 10 Dates Gregory eliminated by papal bull to realign his calendar with the solar year: October 5-14, 1582
• Dates most Catholic countries accepted the Gregorian calendar: 1582-1584
• Date Protestant Germany accepted the Gregorian calendar: partial acceptance in 1700, full acceptance in 1775
• Date Great Britain (and the American colonies) accepted the Gregorian calendar: 1752
• Length of time eliminated by the British Parliament to realign the old calendar (Julian) with the Gregorian calendar: 11 days
• Dates Parliament eliminated: September 3-13, 1752
• Date Japan accepted the Gregorian calendar: 1873
• Date Russia accepted the Gregorian calendar: 1917 (and again in 1940) Date China accepted the Gregorian calendar: 1949
• Date the Eastern Orthodox Church last voted to reject the Gregorian calendar and retain the Julian calendar: 1971
• Length of time the Gregorian calendar is offfrom the true solar year: 25.96768 seconds per year
• Length of time the Gregorian calendar has become misaligned over the 414 years since Gregory's reform in 1582:2 hours, 59 minutes, 12 seconds
• Year in which the Gregorian calendar will be one day ahead of the true solar year: a.d. 4909
• Year that Atomic Time replaced Earth Time as the world's official time standard: 1972
• The year as measured in oscillations of atomic cesium: 290,091,200,500,000,000