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Astro*Dictionary by Michael Erlewine





1 article for "Moslem Calendar"

Moslem Calendar [Astro*Index]

The Islamic calendar year contains 12 hilunar months without intercalation. Consequently, Moslem New Year makes a circuit of the seasons every 33 years. The calendar is kept in adjustment with the Moon by a fixed cycle of 30 calendar years. Months have 30 and 29 days alternately, except the 12th month, with has 29 days in 19 of the years of the cycle, and 30 days in the other 11 years. There are two forms of the cycle, which give dates differing by one day in 348 of the 360 months of the cycle. The calendar equates 360 lunations to 10631 days; the discrepancy with the actual mean lunation amounts to only about one day after 2500 years. For religious purposes, the fixed calendar is not used, but instead the beginning of the month is determined by observation of the lunar crescent, or by some method that gives the nearest practical equivalent. In the religious calendar, the days begin at sunset, on the evening preceding the civil calendar day. Years are reckoned from the Hegira (the flight of Mohammed), which is usually taken to be the epoch AD622 JUL 16 (some Oriental chronologists give it as AD622 JUL 15). The Gregorian dates of the New Year, and of the first day of the principal religious month (Ramadan) are obtained from the form of the 30-year cycle in which the 16th year is a leap year. In the fixed calendar, the first day of Ramadan is the 237th day of the year. But, the day on which it is actually observed varies with local practice, and may not coincide with the tabular date. To find the Gregorian equivalent to any Muhammadan date, multiply the Muhammadan year by 0.970224 and add 621.5774. The whole number will be the AD year, and the decimal multiplied by 365 will the day of the year.

The months of the Islamic calendar are as follows:

No.Month NameDays
03Rabi I30
04Rabi II 29
05Jumada I30
06Jumada II29
    in leap years30


See also: ♦ Calendar


Astro*Index Copyright © 1997 Michael Erlewine