17th of Tammuz, is a Jewish fast day commemorating the breach of the walls of Jerusalem before the destruction of the Second Temple, and marks the beginning of the
three-week mourning period leading up to Tisha B’Av. According to the Mishnah, four other tragedies also occurred on this date, including Moses breaking the original tablets of the Ten Commandments after finding the B’nai Israel worshipping the Golden Calf.  Like other minor fasts, Tzom Tammuz begins at dawn (first light) and ends at nightfall (full dark)