Easter Dating Message to Harry Herndon

From: hjsmithh [mailto:[email protected]] 
Sent: Thursday, September 15, 2005 1:04 PM
To: Richard and Tina Morris
Subject: Easter Dating for Harry Herndon

Dick:

Please see that Harry Herndon gets to see this message:

Harry:

You asked me about why Easter was on March 27 this year (2005)...

Here are some notes from my Easter Dating programs:

--------------------------------------------------------------------------------------------------------------------------
These Pascal programs use the table:

{ Easter falls on the first Sunday following the arbitrary Paschal Full Moon,
  which does not necessarily coincide with a real or astronomical full moon.
  The Paschal Full Moon is calculated by adding 1 to the remainder obtained
  by dividing the year by 19 and applying the following table:

    1 - Apr. 14    6 - Apr. 18   11 - Mar. 25   16 - Mar. 30
    2 - Apr.  3    7 - Apr.  8   12 - Apr. 13   17 - Apr. 17
    3 - Mar. 23    8 - Mar. 28   13 - Apr.  2   18 - Apr.  7
    4 - Apr. 11    9 - Apr. 16   14 - Mar. 22   19 - Mar. 27
    5 - Mar. 31   10 - Apr.  5   15 - Apr. 10
}

But this table is only good for the years 1894 through 2203 (310 years).

Using this table causes Easter dates to have a period of 7600 years (19 * 400)
The true period is 5,700,000 years. 

See the QuickBasic program EasterQB.QB for the larger period.

Also, it is some times stated "The earliest Easter can fall is March 23rd",
but Easter is on March 22nd in 1818 and in 2285.
--------------------------------------------------------------------------------

Based on this 2005 divided by 19 is 105 with a remainder of 10 so the key is 11
which gives March 25 for the Paschal Full Moon. Easter was on March 27 this year
so everything checks out ok.

Maybe you forgot to add one to the remainder.

I just looked at my 2005 calendar and it has April 24 marked as Passover and
Full Moon. I thought that Jewish Passover was on the first full moon of spring,
but this is not always true. I did a little research and found that it is
actually on the 14th day of the lunar month called Nisan in their mixed
lunisolar calendar. Some years have 13 months and some 12, so the month Nisan
always start on a full moon but not always at the vernal equinox. Their year
5765 started 16-Sep-2004 and ends 3-Oct-2005. It had 13 months starting on:

Thu 16-Sep-2004  Rosh Hashana 5765    <-- The Jewish New Year
Fri 15-Oct-2004  Rosh Chodesh Cheshvan
Sun 14-Nov-2004  Rosh Chodesh Kislev
Mon 13-Dec-2004  Rosh Chodesh Tevet
Tue 11-Jan-2005  Rosh Chodesh Sh'vat
Wed 09-Feb-2005  Rosh Chodesh Adar I
Fri 11-Mar-2005  Rosh Chodesh Adar II <-- Leap month
Sun 10-Apr-2005  Rosh Chodesh Nisan   <-- First Month (of spring)
Mon 09-May-2005  Rosh Chodesh Iyyar
Wed 08-Jun-2005  Rosh Chodesh Sivan
Thu 07-Jul-2005  Rosh Chodesh Tamuz
Sat 06-Aug-2005  Rosh Chodesh Av
Sun 04-Sep-2005  Rosh Chodesh Elul

Next year starts on:

Tue 04-Oct-2005  Rosh Hashana 5766    <-- The Jewish New Year

Note: 
All Jewish Holidays begin the evening before the date specified. This is because
the Jewish day actually begins at sundown on the previous night.

-Harry