I originally wrote this program in the Icon programming language on a computer running UNIX. It was intended for the Zenith Z-29 terminal in ANSI mode. It was then ported to MS-DOS. I modified the program to generate HTML for the World Wide Web, and this is what you will see when you run the program.
The Jewish year harmonizes the solar and lunar cycle, using the 19-year cycle of Meton (c. 432 B.C.E.) Meton discovered that after nineteen years the years reckoned using the sun and the moon get back into synch (almost.) It corrects so that certain dates shall not fall on certain days for religious convenience. The Jewish year has six possible lengths: 353,354,355,383,384,385 days, according to the day and time of the new year lunation, and position in the Metonic cycle. Time figures from 6 p.m. the previous night. The lunation of year 1 is calculated to be on a Monday (our Sunday night) at 11:11:20 p.m. Our data table begins with a hypothetical year 0, corresponding to 3762 B.C.E. Calculations in this program are figured in the ancient Babylonian unit of halaqim "parts" of the hour = 1/1080 hour. However this is transparent to the user of the program. A table is used only to speed the calculation of the most common dates.
According to Jewish tradition, the year 1 of the Jewish calendar was the time of "waste and void" referred to in Genesis 1.1. Nothing was yet created, and only a virtual clock started to tick on the first day of that year, heard, as it were, only by the Creator. On the first day of the week (Sunday) the twenty-fourth day of Elul, corresponding to August 22, 3760 B.C.E. (in the Gregorian calendar -- of course this calendar did not exist at that time) He said: Let there be light! and creation began. It concluded by the following Sabbath (Saturday) which was the first day of Tishri, year 2. A cosmic mystery for you to think about.
In this program, I consider the year before the year 1 of the current era to be -1. Of course, this is arbitrary, because no one at that time knew the number of the year. Years were usually reckoned by the ruler, as if we would say "the second year of the presidency of Bill Clinton" or something like that. Others, for convenience, declare this to be year 0, and then the date just cited would be August 22, -3759.
The Jewish/Civil Perpetual Calendar accepts, at the prompt "YEAR(S)", a year of the Jewish calendar, for example "5750", and produces on the screen a calendar of that year with a visually equivalent civil calendar opposite it for easy conversion of dates. The months of the civil year are abbreviated to
and of the Jewish calendar to
[The full names of the Jewish months are
Each Jewish month has its name on the left. The corresponding secular dates will have the name of the month on the right, and when the month changes it will be indicated on the right also. Your screen may not be wide enough to see these civil months, and you will need to click on the bottom bar of your screen, or do whatever else is necessary, to see the part of the page beyond the right margin of your screen. It should print completely on standard size paper, even if you cannot see the civil months on the screen.
If you wish, you may enter a civil year in the form -70 for B.C.E. dates and +70 for C.E. dates. The Jewish year beginning prior to Jan 1 of that year will be displayed, and you can continue with the next Jewish year if you wish to complete the desired civil year. So you might enter "+1970 +1971". You may enter up to five years, separated by spaces, at the prompt, and you can mix Jewish and Civil dates. Be sure to leave a space between years. There should be no space between the + or - sign and the following year if you are entering a civil year.
If you use the Opera browser you must enter civil dates of the current era as, for example, 1970AD or 1970CE. Do not put a space between the numerals and the AD or CE. You can, if you wish, use this form for other browsers too, but for Opera, you must use it.
The year 0 is not meaningful in either calendar. No date prior to 1 in the Jewish calendar can be entered.
A status line appears after each set of three Jewish months, and indicates the civil and Jewish year, and the number of days in each. This information is current for what immediately precedes. If the Jewish year has thirteen months, there will be an extra status line at the end. Jewish years may contain one of six different lengths, according to circumstances. Leap years occur every three or four years.
All civil dates are according to the Gregorian Calendar which first came into use in 1582 and was accepted in different places at different times. Prior to that date the Julian calendar was in use. At the present time the Julian calendar is 13 days behind the Gregorian Calendar, so that January 20 1990 in our reckoning is January 7 in the Julian Calendar. (This is why the Russian "October Revolution" is now celebrated in November!) The following table shows the number of days that must be subtracted from the Gregorian date given here to find the Julian date. In the centuries before the current era the calendar then in use was intercalated erratically by the Romans, so a simple subtraction is not possible. However, dates given are correct according to the Gregorian calendar.
Century # to subtract Century # to subtract 21 13 11 6 20 13 10 5 19 12 9 4 18 11 8 4 17 10 7 3 16 10 6 2 15 9 5 1 14 8 4 1 13 7 3 0 12 7 2 -1
You should be able to use back and print in your browser to rerun the program, or print the result.
While every effort has been made to ensure the accuracy of this program, mistakes can occur, and so its accuracy is not guaranteed.
If you would like to see the original code, help yourself, but it is only likely to be of interest to programmers. If you wish to use the program for your own purposes, you need to go to the University of Arizona website dealing with the Icon Programming Language referenced below. There you can download the necessary software for various platforms. The code for the MSDOS version given here should not need too much alteration.
Acknowledgment is made to the classic work Qiddush Hahodesh by Rabbenu Moshe ben Maimon, and to A Guide to the Solar-Lunar Calendar by B. Elihu Rothblatt.
Alan D. Corré, Emeritus Professor of Hebrew Studies, University of Wisconsin-Milwaukee.
Tammuz 13, 5756/June 29, 1996
The Calendar is listed in Yahoo.
More information on the Icon Programming Language?
More information by Remy Landau?
corre@uwm.edu