The Shulchan Aruch (Y”D 266) states that when a baby is born during the time known as bein hashmashos (twilight zone – a time which is halachically unclear if it is still day or it is already considered night and the halachic beginning of the next day), the bris should take place on the 9th day. For example: a baby is born on Tuesday evening and we are unsure if it was halachically yom shlishi (Tuesday) – and the bris should take place on the following Tuesday, or it was already leil reviyi (Tuesday night) – and the bris should take place on the following Wednesday. Since we are in doubt, the halachah dictates that the bris should take place on the following Wednesday, because it is better for a bris to be performed on the 9th day than on the 7th day.
When is Bein Hashmashos?
In order to understand this subject of bein hashmashos properly it is essential to have a basic understanding and background of the various opinions of bein hashmashos.
The Gemara in Psachim 92 a states that from sunset until the stars come out is equivalent to the time that it takes the average person to walk 4 mil. (A mil is a halachic mile and is somewhat less than a mile). Many poskim assert that it takes 18 minutes to walk a mil, which means that – according to this Gemara in Peschim – the stars come out at 72 minutes after sunset, and that is the time of the halachic commencement of night. Thus, according to this Gemara it would seem that night begins at 72 minutes after shkiah.
However, the Gemara in Shabbos (34b) seems to say otherwise. The Gemara there states that the time period from sunset until nightfall (known as bein hashmashos) is 3/4 of a mil, which based on the aforementioned formula (mil = 18 minutes) would be: 3/4 of a mil = 13 and 1/2 minutes. Thus, it would seem from the Gemara in Shabbos that night is at 13 and 1/2 minutes after sunset.
There are two basic ways to reconcile this apparent contradiction. Tosfos quotes the famous opinion of Rabeinu Tam, who explains that there are two shkios. There is the physical setting of the sun under the horizon, which has little halachic ramifications; even after sunset it is still day. The second shkiah (the halachic sunset) takes place when the rays of the sun start to disappear from the horizon. That takes place at 3 and 1/4 mil (58 and 1/2 minutes after sunset), which is the beginning of bein hashmashos (halachic twilight) and continues until 72 minutes, which is when the stars come out and the night begins.
However, the Geonim (who lived over 1000 years ago, prior to the Rishonim) – as well as the Vilna Gaon, who strongly concurs with their opinion – explain that the sun setting under the horizon is, indeed, the commencement of the halachic twilight (bein hashmashos) and continues for 3/4 of a mil (13 and 1/2 minutes), which is when it is considered halachically night. They explain that the Gemara in Pesachim that gives the number of 4 mil, is referring to the time when all of the stars came out; but the halachic night starts much earlier. The Gra points out that this time frame will not hold true for every locale: it is only in Eretz Yisroel, or similar latitudes, where it does get dark so early. However, in Northern countries, such as Lithuania – where the Gra lived – or in the USA, the stars come out – and the night commences – somewhat later.
As far as which stars are the ones that tell us that it is halachically night, it is essentially enough to have middle-size stars. However, since it is hard for people to distinguish what is considered middle-size, we, therefore, require for mitzvos min-hatorah to have small stars.
By Rabbi Nachum Scheiner,
Rosh Kollel Ohr Chaim, Mohel Mumcheh
Rabbi Nachum Scheiner of Bais Medrash Ohr Chaim has been raising the bar of Torah learning with great success throughout the Monsey community. Rabbi Scheiner heads the Kollel Boker, the Evening Kollel, the Sunday morning Halacha Chabura, Yeshivas Bein Hazmanim, Yarchei Kallahs on legal Holidays, and the Friday morning Shovavim Learning.