A starry night: Shekiah, bein ha-shmashot, and tzeit ha-kochavim

Abstract

Since time immemorial, there has been a dispute amongst the Rabbis as to the length of time between Shekiah and Tzeit Ha-kochavim. Starting from the Talmud, there is a contradiction as to the length of time in mil between Shekiah and Tzeit Ha-kochavim. The resolution to this conflict resulted in two main opinions, the Geonim and Rabbeinu Tam. Whereas the Geonim emphasize that the Talmud in Shabbat is correct, Rabbeinu Tam opined that the Talmud in Pesachim is correct. This led to an age-long debate as to how to determine Tzeit Ha-kochavim. In addition, several other factors are necessary to determine in order to definitively conclude the time of Tzeit Ha-kochavim. These include converting the length of a mil into minutes and halakhic hours. Moreover, there are several contradictions within the medieval opinions, further complicating matters. As a result, a possible correlation can be drawn between those following the opinion of Rabbeinu Tam and the advent of the clock. However, at the end of the day (pun intended), many contemporary Rabbinic authorities advocate for the calculation of Tzeit Hakochavim based on depression angles and degrees the sun is below the horizon.