A
few people have asked us how we could publish the date of the New
Moon before it was actually observed. This is actually an
important question.
There are in fact two schools of thought on this very issue
among the Karaites.
Potential
Visibility
The
issue at stake is really what does one do if modern
astronomy tells us that the moon is easily visible but it is
not seen because
of clouds? Most Karaites are of the opinion that in such a
case we must celebrate New Moon Day, even though the moon
has not actually
been sighted.
It
is worth considering an actual example of this. A few
years ago on a particular occasion the moon should have been
easily visible
from Israel. Indeed, on the previous evening, the moon had
already been sighted half way around the world in the US.
Now there is
a hard and fast rule that if the moon is visible in a given
location
it will be visible everywhere to the west of that location on
the same latitude. So if the moon was seen in the southern
United States
then it has to be visible in Israel (on the following evening).
The
question of course arises what
to do when modern astronomy can't say with certainty whether
the New
Moon will be visible or not. This happens about once a year
and we had an example of it last year in the 7th Month
(Tishrei). In such
cases, we have no choice but to go by raw observations, not taking
the appearance of clouds into account. But when modern
astronomy can tell us with a certainty if the moon will be
visible then
we observe that evening as Rosh Hodesh even if the moon was not
sighted because of heavy clouds. In Karaite jargon this is
called "Potential
Visibility" (Efsharut HaRe'iyah), that is, the moon is
potentially visible and will be seen assuming there are no
clouds in the
way. It is only in the past 10 years that truly reliable methods of determining Potential
Visibility have been developed using modern astronomy. The
concept of Potential
Visibility is much older though, although in earlier
centuries
it only worked in extreme case where it was obvious to the
ancients that the moon was visible on a particular evening.
For example,
if the crescent moon was sighted before sunset, the ancient
Karaites believed that the moon must have been visible on
the previous evening.
It turns out that this belief, which was held by the
greatest
astronomers of that era, was in fact incorrect! Because of
this we are very careful with our use of modern astronomy
and only follow
a method that has proven itself in repeated instances. And if
there is any doubt then we go by raw observation.
Actual
Visibility with 30 Day Maximum
The
second school of thought was the opinion of the 8th century Anan
ben David. Anan believed in going by raw observation,
although he argued
that even if the moon was not seen, the maximum length of a month
was 30 days (so even if it is cloudy for several days in a row,
the month is still no longer than 30 days). Of course, this
maximum length
for the month was itself based on the conclusions of some rather
rudimentary astronomy. Truth be told, in Anan's day this was
probably the best method. The astronomical calculations of
his day were
at best a shot in the dark, being wrong as often as they were right.
This was clear to anyone regularly observing the New Moon.
But
today our calculations can tell us with incredible accuracy
whether the moon will be visible or not. And they can also
tell us when
there is uncertainty, so that we can revert to the method of Anan
in such cases.
We
at the Karaite Korner have no intention of telling our readers what
to do. We urge you to follow the Karaite motto which says:
"Search well
in the Scripture and do not rely on anyone's opinion". We
provide the information about New Moon sightings to those
that wish to follow
the method of Raw Observation. And for those who wish to follow
the method of Potential Visibility, the New Moon sightings are
an important reminder of how accurate our calculations are
and more importantly
what their limitations are. And since most months there are
no clouds and the moon is seen on the calculated dates, one can
remove any doubt when Potential Visibility turns into Actual
Visibility.
From the Karaite Korner Newsletter #67 To join:
http://groups.yahoo.com/group/karaite_korner_news/