Spencer's Easter formula

Spencer's Easter Formula is an algorithm used to determine the date of Easter .

The rule was described by the British astronomer Harold Spencer Jones in 1922 , but was published by an anonymous author as early as 1876.

algorithm

Publication from 1876

Used division with remainder .

${\displaystyle a=Jahr~{\rm {mod}}~19}$
${\displaystyle b=Jahr~{\rm {div}}~100}$
${\displaystyle c=Jahr~{\rm {mod}}~100}$
${\displaystyle d=b~{\rm {div}}~4}$
${\displaystyle e=b~{\rm {mod}}~4}$
${\displaystyle f=(b+8)~{\rm {div}}~25}$
${\displaystyle g=(b-f+1)~{\rm {div}}~3}$
${\displaystyle h=(19a+b-d-g+15)~{\rm {mod}}~30}$
${\displaystyle i=c~{\rm {div}}~4}$
${\displaystyle k=c~{\rm {mod}}~4}$
${\displaystyle l=(32+2e+2i-h-k)~{\rm {mod}}~7}$
${\displaystyle m=(a+11h+22l)~{\rm {div}}~451}$
${\displaystyle n=(h+l-7m+114)~{\rm {div}}~31}$
${\displaystyle p=(h+l-7m+114)~{\rm {mod}}~31}$

The date of Easter Sunday is , and is the number of the month (March or April) . ${\displaystyle p+1}$ ${\displaystyle n}$

Application of the algorithm for the coming years:

Variable                 2018   2019   2020   2021   2022
---------------------------------------------------------
a                           4      5      6      7      8
b                          20     20     20     20     20
c                          18     19     20     21     22
d                           5      5      5      5      5
e                           0      0      0      0      0
f                           1      1      1      1      1
g                           6      6      6      6      6
h                          10     29     18      7     26
i                           4      4      5      5      5
k                           2      3      0      1      2
l                           0      1      3      6      0
m                           0      0      0      0      0
n                           4      4      4      4      4
p+1                         1     21     12      4     17
Osterdatum: Sonntag,     1.4.  21.4.  12.4.   4.4.  17.4.

See also

• Gaussian Easter formula

literature

• Jean Meeus : Astronomical algorithms. Willmann-Bell, Richmond 1998, p. 67 f.
• To find Easter. In: Nature , 1876 (13), 338, p. 487, doi : 10.1038 / 013487a0 .