Today, we use large and small printed calendars, diaries and various electronic gadgets to keep track of birthdays, anniversaries, dentist appointments, holidays and school vacations.
In ancient times, people needed calendars for the seasons: when to plant, when rains might start, when the harvest would be ready and when to celebrate, as well as religious, celestial and astrological happenings.
The word calendar comes from Latin, kalendarium (account book), which comes from kalendae, or calends, the day when interest on debts became due in the Roman calendar. Calendar systems are solar and based on the sun (Ancient Egyptian, Gregorian, etc.); lunar and based on the moon's phases (Islamic, Jewish, etc.) or a combination (Han Chinese, Tibetan, etc.).
Some count a new day from sunset of the previous day (Jewish calendar), some begin the new day at just after midnight. The Islamic calendar depends on physical sighting of the moon's phases, making calendars nearly impossible to print ahead of time. Until 1957, India had some 30 different calendars, and Zoroastrians use three types of calendars.
When we lived in Iran in the 1970s, our printed calendar showed Gregorian (the general-use calendar), in addition to Jewish, Persian, Armenian (Greek Orthodox), Zoroastrian and Baha'i dates. Not much room to write down birthdays!
JULIAN vs. GREGORIAN
Julius Caesar introduced his namesake Julian calendar in 46 BC, with New Year celebrated on March 25. This was used until the Gregorian calendar was suggested by a Naples doctor, Aloysius Lilius, and adopted by Pope Gregory XIII after the Council of Trent (1545-1563). In February 1582, the Pope decreed the new system, but not all countries used it immediately.
It established January 1 as New Year's Day, and also ordered that 10 days should be dropped from October 1582, and that October 4 would be followed by October 15. Immediately adopting it were Italy, Poland, Portugal and Spain, followed by other Catholic countries. Protestant countries eventually switched. Greek Orthodox countries didn't change until the early 20th century. Russia switched in 1918, following the 1917 revolution.
When the Gregorian was adopted, various countries lost days at different times as it came into use. When England finally adopted it in 1752 after a 170-year delay, 11 days were dropped - many people thought they had lost 11 days' pay and protested. Genealogists need to be aware that there are somewhat unclear record dates for English and colonial records from 1 January-24 March, in the years before 1753.
The change to the "new" New Year's day was encouraged by the boom in world trade, and businesses wanted a clearly stated year. However, because different countries adopted the Gregorian at different times, some records written in "split year" or "double dating," during 1582-1752. Countries using the "old style" Julian calendar might write February 14, 1714/15, which indicated the Julian calendar was still being used, but the Gregorian date was February 25, 1715. The Encyclopedia of Genealogy link below offers an excellent article on more details of the confusion and how genealogists need to reference such dates.
CALCULATING & CONVERTING
Why do we need calendar conversions? The first reason is to better understand ancestral birth, marriage and death records.
The switchover from Julian to Gregorian impacts genealogical records. A vital record based on the French Revolutionary Calendar is meaningless without a conversion program.
For example, dates of death are important to the Jewish people, who traditionally recite special prayers on a relative's memorial day according to the Jewish calendar. Gravestones may only show the Hebrew date, which must be converted into Gregorian to learn the proper day.
MyHeritage offers conversion for Gregorian, Jewish and the French Revolutionary Calendar. Go to MyHeritage Family Tree Builder to any individual's page and hit EDIT. On any line for a date, you'll see a calendar-like icon, as seen below.
In the screen that will open, as shown below, enter any date. Click one of the other calendar conversion buttons and see the date in the other format.
HAPPY NEW YEAR
The Gregorian New Year begins 1 January; the Persian New Year (Now Ruz) begins 20-21 March, at the spring equinox. The Jewish New Year (Rosh Hashana) begins in September or early October, while Chinese New Year falls between 21 January-21 February.
To denote ancient from more modern years, Gregorian uses BC (Before Christ) and AD (Latin, anno domini "Year of Our Lord"), the Jewish calendar uses CE (Common Era) and BCE (Before Common Era), and the Baha’i use BE (Baha’i Era).
While Western calendars are linear, progressing from a specific starting point, traditional Chinese culture uses a 60-year cyclical pattern (marked as the Year of the Rat, Horse, etc.). China uses the administrative Gregorian civil calendar with the traditional Chinese calendar for festivals and agricultural activities.
FRENCH REVOLUTIONARY CALENDAR
The French Revolutionary Calendar (French Republican Calendar) was introduced on 24 November 1793 and abandoned 1 January 1806. Each month had three weeks of 10 days; people worked for nine days before a one-day “weekend.” This caused another revolution, leading to its disappearance.
The Jewish calendar day begins at sunset. Observant families will light Sabbath candles 20 minutes before sunset and, according to religious law, the end of the Sabbath only occurs when one can see three stars in the sky.
Fortunately, these calculations have been made mathematically and are available according to city, usually printed in local community calendars and newspapers. One doesn’t need to stand outdoors in a blizzard or rain storm and attempt to see the stars, a clearly impossible task.
Genealogically, calendar convertors such as those on MyHeritage.com make it simple to discover what Gregorian date equals which Jewish date. Thus, a birth date of 27 Nissan 5580 corresponds to 11 April 1820. However, the person may have been born the previous day (10 April 1820) after sunset.
EXTRA DAYS & MONTHS
Calendars add a leap year or an extra month to make up for differences in year’s length. Gregorian adds a leap year, with an extra day in February in every year divided evenly by four, while the Jewish calendar adds an extra month, Adar II, by adding an entire month about every three years. Some calendars, such as the Islamic, float - which means a holiday may fall in different seasons.
Calendars are fascinating and there is much more to know. If you'd like to learn more, try the following links:
http://www.eogen.com/CalendarChange16thCentury - Calendars and genealogical issues
www.calendopedia.com - Calendar Comparison Chart and interesting information on many calendars.
http://calendopedia.com/chinese.htm - A good chart of the Chinese cyclical calendar
www.calendropedia.com/gregory.htm - A table of which countries adopted the Gregorian and when and the "lost days."
http://www.jewishgen.org/InfoFiles/m_calint.htm - More Jewish calendar information
http://www.calendarhome.com/converter/ - More help with Gregorian, Julian, Mayan, Persian, Indian, Hebrew, Baha'i, Islamic, French Republican and others.
http://members.pcug.org.au/~dfry/calendar.html - Calendar comparison by month.
I look forward to reading your comments and questions on calendar-related issues.