Beginning of Night
Nighttime, which we mentioned is the borderline between two consecutive days, is the moment when three stars of the second magnitude become visible (zet ha-kokabim). Thus the length of a day is "from the rising of the morning" (Neh 4:21) "until the stars appear."
It is important in Judaism that the "zet ha-kokabim" appears during Sabbaths and feast days at different times because the appearance of stars varies from day to day and from place to place. In modern Judaism these figures are calculated.
The Jewish Calendar in Ancient Hebrew History
