American Falls press. [volume] (American Falls, Idaho) 1907-1937, 1913-03-20
RASTER DATE CHANGES BE
CAUSE GOVERNED BY MOON.
BY Garrett r. serviss in Butte Miner

or, marking the anniversary of the
resurrection Of Christ, falls this yea
within one day of it's earliest posi-.
BILE date. 1t comes on Sunday March
20. Last year it fell on Sunday Apri
It'll. Some years is occurs severa.
weeks later.
ALI other an n~iversaries except
Master and the holy days associated
with 1t, fall on a fixed day of each
year and people who are not fami
! lar with what is called the ecclesias-
teal calendar are often greatly puz-
zled to account for the wandering
Of this great festival, whose OK
treme dates may be as much as five
weeks apart. A late Easter has
more flowers and more sunshine; an
early one, like that of the present
year. sometims feels the last chill
OF the departed winter.
The primary reason for the varia-
BILE date OF Easter is the fact that it
10 tn e only great festival in Christ
Ian countries hat depends directly
on the monthly motion of the moon.
At he same time it is effected by
the yearly motion of the sun, since
its date is governed by the vernal
equinox, which is the point in the
year when the sun crosses the equa-
tor from the southern into the north
ern hemisphere.
But the year and the month are
not commensurate lengths of time
that is to say, there is not an even
number of lunar months in a year.
A lunar month is not the same as a
calendar month, but it represents
the time from one full moon to the
next, which is on IN average about
20 days, l hour, Al minutes. A
year, which is measured by the APP
parent motion of the sun, is on the
average 365A days. Now it cannot
be divided by the period of a lunar
month without leaving a remainder
In consequence, a full noon may
OCCuI d. dAy LlulS Ill lAC tOuioO vi
an ordinary month.
But the rule 70. finding the date
of Easter is that it must fall upon
Sunday Immediately following the
first full moon, which occurs on reg
ular date of the equinox.
Last year the first full moon fol-
lowing the equinox happened on
April 1, which was Monday. The
next following Sunday, according to
the rult was Easter day. This
year the full moon OF the equinox,
or the paschal moon as it is called
in the church calendar, falls on the
%, which is a Saturday, and the
next day. the 23rd. being Sunday, be
comes Easter day.
Inasmuch as Christmas day, which
is celebrated as the anniversary OF
the birth of Christ, m on a fixed
date every year, December 20, II
would appear much simpler to keep
Easter also as near a fixed date as
possible. 1t could not be asolute-
" fixed because of the settled Gus
tom of celebrating it on a Sunday,
but as the astronomer Clavius point
ed out centuries ago, a reasonable
degree of regularity could be intro
duced by making Easter the first
Sunday after the eQuinax without
regard to the phase of the moon. II
that rule was adopted the date I
Easter would still be a movable
one, but it's wandering would be
kept within one week of a fixed
date.
The existing system of determln-
ing the date of Easter is based on
a discovery made more than 4oo
years before Christ, by a Greek as
trologer Melton. He found that zoo
lunar months are almost exactly
equal in total length to 10 years
of 1854 days each, There Is a
difference of about two hours IN
course of the 10 years This per-
iod is called the Metonic cycle and
its division into years gives rise 10
the Golden Numbers" which q
cate the place of n year IN tue
cycle At the beginning OF 'ne
cycle, which as used in the eecleslas-
tical calendar, is reckoned from Jan
l of the year /, B.. c., a new moon
happend to fall on JAM. LIST. Every
10 years since then there has been
a new moon at the beginning OF Jam
uary. but during the intermeoiat
years OF the cycle, the first new
of the year occurs at dif1ef-
ent dates in January, which are al
the same for years occupying
the same place in the cycle ms
place is called the golden number
and nv its aid. though a somewhat