Defining Twilight - Shabbat 34
What IS twilight [beyn ha-shemashot – literally “between the suns”]? Keep in mind that the Rabbis were trying to define this concept without the benefit of clocks or a strict sense of universal time – today we could just define it by something like 6:15-6:42pm. Imagine you were camping without a watch or a computer and had to decide when it was nighttime – the sun setting is a very gradual process, and while there is clearly a difference between a red glowing sunset and nighttime under the stars, what is the dividing line between one and the other? Rabbi Judah claims that while as the eastern sky has a reddish color, and while the lower horizon is “paler” than the upper, it is still twilight; once the upper and lower horizons are of the same color, it is night. To my mind, this is as good a definition as any other.
The reason defining twilight is important for the Talmud’s rabbis is based on another question: does twilight count as day or as night? That is, on a Friday evening, how can you know when it is Shabbat, or not yet? On one hand, twilight is considered a “doubtful” time, where one can be flexible in assigning blame for not completing tasks like the eruv in time – “a doubt in Rabbinical law is judged leniently.” On the other, because it is an uncertain time, the rabbis would rather be safe and put in effect the more strict requirements – just in case. This is why in traditional Jewish practice there is a “margin of error” around candlelighting times for Shabbat. Because at that time of day, one has entered. . .the twilight zone.
Rabbi Adam Chalom