Introduction
Few halachic questions come up as
often as the one about when the day starts. Once a week all religious Jews ask
“When does Shabbos come in?” (except in the summer for those who bring it in
early at the same time), and a day later they ask “When does Shabbos go out?”
Every day our davening times are affected by the same question, and at times
like Chanuka things get even more confusing.
For this reason, I am sure that
virtually all readers will have at least some knowledge of the topic. Some will
also know how complex the issue is in the gemara and commentaries, and
hopefully some will also know enough to argue with some of my conclusions.
Sunset and Stars
We first need to state an
assumption which may be obvious for most. The halachic day (24 hours) starts at
the beginning of the night.[1] Thus
the critical question is when the night starts.
The gemara derives that the
halachic daytime goes from Alos Hashachar (dawn) until the stars come
out. Thus mitzvos such as circumcision, which must be done during the day, have
to be done during this period.[2] From here it would seem that we just need to
define more clearly what ‘the stars coming out’ means, and this time will be
the start of the next day.
The reality is not that simple.
Elsewhere we are introduced to the concept of Bein Hashmashos (literally
‘between the suns’), a time when uncertainty exists whether it is day or night.
Several opinions exist in the gemara, but for the purposes of simplification
here we will present just the view of R’ Yehuda, according to Rabba (the view
that is accepted in halacha, at least for most purposes).
Once the sun sets, we have
entered Bein Hashmashos. This continues as long as there is redness on
the western horizon, and even after the bottom part of the horizon has darkened.
Only when the top part of the horizon has darkened to the same degree as the
bottom part, we can be sure that it is night. The length of Bein Hashmashos
is the time that it takes to walk three quarters of a mil (mil= 2000
amos, about 960 metres).[3]
The gemara continues with another
way to tell the difference between day and night. If only one star can be seen,
it is definitely still day. If two can be seen, it is Bein Hashmashos.
If three can be seen, it is definitely night. The gemara clarifies that the
stars referred to are not the big ones that can be seen even during the day
(perhaps a reference to Venus), nor the small ones that can only be seen well
into the night. Rather, we are referring to medium-sized stars.[4]
Tosfos point out the seemingly
clear contradiction. If, as the gemara says in one place unambiguously, night
starts when the stars come out, why elsewhere are we told about a doubtful
period? They answer that the uncertainty is over the very definition of ‘the
stars coming out,’ as is explicit in the gemara that there are different sizes
of stars.[5] The
implication is that from sunset there is already a doubt whether ‘the stars
have come out.’[6]
The Rambam writes that the period
between sunset and the appearance of three medium-sized stars is
called Bein Hashmashos in all places.[7]
Understandably, when formulating most of the other halachos dependant on day
and night he gives no further explanation, relying on the definition given
already.
However, there is one exception.
In Hilchos Kiddush HaChodesh, the Rambam states the halacha that the
declaration of the new month can only be done during the day.[8] Here
he clarifies that this declaration can be made until two stars have come out. After
this it is too late (as it may already be night), and the declaration has to
wait until morning.[9] What is
special about Kiddush HaChodesh?[10]
The Maharalbach explains that
only when it comes to Kiddush HaChodesh can we rely on stars to determine when
the day has ended, as this mitzvah is under the jurisdiction of Beis Din. Due
to the difficulty in determining exactly when the right stars come out, we need
a clearer measurement for mitzvos that all are responsible for. Thus from
sunset we must be concerned that the next day may have already started.
However, when it comes to Kiddush HaChodesh, Beis Din can know that it is still
day even after sunset.[11]
How long is a mil?
Even after we have been given
sunset as a clear indicator of the start of Bein Hashmashos, we are left with
the appearance of three stars as the indicator of the end of it.[12]
However, as we mentioned already, Chazal did tell us that Bein Hashmashos lasts
the time it takes to walk three quarters of a mil. If we can determine how much
time this is, now that we have clocks we should be able to pinpoint Bein Hashmashos
exactly.
Theoretically, one way to do this
would be to use the time that it takes an average person to walk three quarters
of a mil (about 740 metres[13]). This
would give us a time of about nine minutes. However, this is impossible for
many reasons. Firstly, nine minutes after sunset no-one can see three stars.
Secondly, as we will see this would not fit with what the gemara says
elsewhere. We must conclude that in the time of Chazal people did not walk as
fast as they do now.[14]
The truth is that how long it
took to walk a mil in the time of Chazal can be extrapolated directly from
another section of the gemara.[15]
Rabbah bar bar Chana says in the name of R’ Yochanan that an average person can
walk 10 parsa (parsa= 4 mil) in a day. The first 5 mil are walked from Alos
Hashachar until sunrise, and the last 5 mil are walked between sunset and the
stars coming out.
However, this statement is
refuted by a braisa (Mishnaic period source) that says that only 4 mil
are walked between Alos Hashachar and sunrise, and another 4 mil between sunset
and the appearance of stars.[16] Thus
the time taken for the sun to pass through the ‘thickness of the sky’ is a
tenth of the length of the day.
The gemara concludes that
although the statement of R’ Yochanan as given above is definitely problematic,
it is possible that a more accurate version of his statement is correct. It
could be that R’ Yochanan “only spoke about the day, and the rabbis made a mistake
in calculating the time before and after.” How we understand this correction of
the original statement is critical.
Rashi explains that R’ Yochanan
merely said that an average person walks 10 parsa a day, and did not specify when
they start or finish walking. In fact they usually start before Alos Hashachar
and finish after the stars have appeared, allowing them to walk 5 mil
before sunrise and 5 mil after sunset. Between Alos Hashachar and sunrise, and
between sunset and the stars appearing, there is only enough time to walk 4 mil.
With this information,
calculating the time taken to walk a mil is relatively simple. Assuming that
the gemara is talking about the average day, with 12 hours between sunset and
sunrise,[17] it takes 12
hours to walk 8 parsa (one parsa is walked before sunrise, and another parsa
after sunset). Thus it takes one and a half hours to walk one parsa, or 22.5
minutes to walk a mil. So Bein Hashmashos is three quarters of 22.5 minutes,
just under 17 minutes.
The Vilna Gaon explains
differently. R’ Yochanan really meant that a person walks 10 parsa in the 12
hours between sunrise and sunset, but he was misinterpreted to include the time
before sunrise and after sunset. Thus each parsa takes 72 minutes to walk, and
each mil 18 minutes. The length of Bein Hashmashos is three quarters of 18
minutes, 13.5 minutes.[18] [19]
The Rambam writes that one can
walk 15 mil between sunrise and midday (6 hours).[20]
According to this a mil takes 24 minutes to walk,[21] so
Bein Hashmashos is three quarters of this, 18 minutes. This position seems
difficult, being in accordance with the original version of the statement of R’
Yochanan which the gemara rejected.[22]
Practical Application
Whether Bein Hashmashos is 13.5,
17 or 18 minutes, there seems to be a problem when it comes to translating this
into reality. Even in Eretz Yisrael, we generally see three stars only about 25
minutes after sunset[23]
(this increases further from the equator).
Even if we do accept a length of
Bein Hashmashos of 17-18 minutes (13.5 is usually discounted as being
unrealistic), this is certainly not uniform. As the Vilna Gaon points out, the
length varies during the year, and with altitude.[24]
In order to achieve logical times for
the whole year in all places, many suggest that we assume a Bein Hashmashos of
18 minutes at sea level, at the equinox in Eretz Yisrael.[25] We
should measure how many degrees the sun is below the horizon 18 minutes after
sunset, and extrapolate that at all times and in all places, ‘the stars come
out’ when the sun is this number of degrees below the horizon.[26]
In my eyes, the big problem with
this is that the gemara glaringly omitted to mention any difference based on
time of year or altitude. To assume that the gemara spoke specifically at the
equinox and at sea level seems fanciful. The problem is magnified by the fact
that some of the differing views in the gemara disagree over only a few
minutes, implying that they believed the times they were giving were to a high
degree of accuracy.
It is interesting to note that as
we quoted above, the Rambam in Hilchos Shabbos tells us only that Bein
Hashmashos is until the stars have come out, and does not say how long this is.
Elsewhere he tells us vaguely that it is ‘about a third of an hour.’[27] It could
be that he was aware that the times given in the gemara are not 100% reliable,
and to be safe we should check for the stars ourselves.
I conclude that although the
halachic calendars we have are immensely helpful, we should be aware that they
are not the final word. While the times given for the end of Shabbos usually
include enough stringency to make them reliable, the more sophisticated
calendars that give times that appear to be exceedingly accurate are probably
not. When it comes to mitzvos like saying Shema at night, or deciding which day
a baby boy was born for the purposes of fixing when the Bris will be, great
care must be taken.
[1]
Although Rashbam in his commentary to Bereishis 1:5 (in uncensored versions)
seems to dispute this, his explanation was only meant on the level of pshat
(simple meaning) and not halachically. This is clear from his introduction.
[2] Megila 20b,
from a verse in Nechemia 4:15
[3] Shabbos 34b
[4] Ibid. 35b
[6]
Although based on other comments of Tosfos, the ‘sunset’ they are referring to
is not what it seems. They accept the explanation of Rabeinu Tam, that sunset
here means ‘the end of the sunset’, which is much later than what we call
sunset. Throughout this post we have assumed the position of the Vilna Gaon
(and the Geonim), who rejects the view of Rabbeinu Tam as it does not fit with
reality.
[7] Hilchos
Shabbos 5:4
[8] When there
is a Sanhedrin, for the start of the new month to be on the thirtieth day from
the previous new month, it was necessary to first accept testimony about the
sighting of the new moon and then for the Sanhedrin to designate that day as
Rosh Chodesh.
[9]
Hilchos Kiddush HaChodesh 2:9. Although
there is a seeming internal contradiction within this halacha, almost all the
commentators I have seen explain that the cut-off point is two stars, and based
on the gemara this must be the case. See for example Biur Chadash Maspik.
[10]
According to the Rambam sunset cannot be synonymous to the appearance of two
stars (similar to the answer of Tosfos above), as if this was the case he would
not have needed to give a different indicator of Bein Hashmashos to the normal
one.
[11] Shu”t
Maharalbach siman 144. He explains that the appearance of two stars sometimes occurs
immediatetly at sunset, but it can be up to a twelfth of a mil (one and a half
to two minutes) later than this.
[12] This
is not a difficulty with the explanation of the Maharlbach, as one who cannot
discern three stars will remain in doubt until he can. It is only critical to
have a clear indicator of the beginning of Bein Hashmashos, so that people do not
erroneously think it is still day when they fail to notice the stars. See Piskei Ri’az,
Shabbos 2:4 (paragraph 8) who says that the indicator of the appearance of
stars was given only as a stringency and cannot be relied on to be lenient.
[13] As
you might expect, this is also an issue of a debate and according to some
poskim it is as
much as 864 metres. The figure given above is the more accepted one (and also
the more realistic one, but showing this would require another post).
[14] This
fact can be supported by other evidence from sources in halacha and elsewhere,
but there is a limit to what I can write here.
[15] Pesachim
94a
[16] The
commentaries point out the seeming major contradiction between this and the
three quarters of a mil measurement given above, a problem I have not dealt
with here.
[17] Many
early poskim mistakenly believed that the average day has twelve hours between
Alos Hashachar and the appearance of stars, throwing these calculations off.
See Levush, Orach Chaim 267:2 and Biur HaGra,
Orach Chaim 459:2 who point out this mistake.
[18] Biur
HaGra ibid. He
brings support for this from the Rambam’s commentary to the first Mishna in
Berachos. Here the Rambam says that the time between Alos Hashachar and sunrise
is 72 minutes (although it seems that the Rambam retracted from this position,
as we will explain).
[19] It
is worth noting that the Gra in Orach Chaim 261:2 writes that the statement
that one star is day, two Bein Hashmashos and three night, is according to the
differing view of R’ Yosi. His position is that Bein Hashmashos does not start
at sunset, but 13.5 minutes later (according to the Gra), and lasts only for ‘the
twinkling of an eye.’
[20] Hilchos
Korban Pesach 5:9
[21] A position
stated also in his commentary to the Mishna in Pesachim 3:2
[22] The Gra
writes that the Rambam must have had a different text of the gemara.
[23]
Although some have claimed that people with astronomical knowledge do know
where to see stars at the appropriate times. See this article
(in Hebrew) for details.
[24] Places
that are high up (like Yerushalayim) see sunset later, but the appearance of
stars is unaffected by altitude. Thus Bein Hashmashos is shorter at higher altitudes.
[25] The
equinox is chosen in order to achieve 12 hours between sunrise and sunset.
[26] At
the equinox Bein Hashmashos is at its shortest. Using this method means that in
the middle of the winter and in the middle of the summer, Bein
Hashmashos in Eretz Yisrael at sea level is 24 minutes.
[27] Hilchos
Trumos 7:2. This fits with the time of 18 minutes that follows from what he wrote
in Hilchos Korban Pesach.
