The Seventeenth of Tammuz (Hebrew: שבעה עשר בתמוז, Shiv'ah Asar b'Tammuz) is a Jewish fast day commemorating the breach of the walls of Jerusalem before the destruction of the Second Temple. It falls on the 17th day of the Hebrew month of Tammuz and marks the beginning of the three-week mourning period leading up to Tisha B'Av. Like other minor fasts, Tzom Tammuz begins at dawn (first light) and ends at nightfall (full dark).
Tzom Tammuz begins at dawn on Thu, 09 July 2020.
https://www.hebcal.com/holidays/tzom-tammuz
Tzom Tammuz begins at dawn on Thu, 09 July 2020.
https://www.hebcal.com/holidays/tzom-tammuz
Shabbat Chazon ("Sabbath [of] vision" שבת חזון) takes its name from the Haftarah that is read on the Shabbat immediately prior to the mournful fast of Tisha B'Av, from the words of rebuke and doom coming from Isaiah in the Book of Isaiah 1:1-27. It is also referred to as the Black Sabbath due to its status as the saddest Shabbat of the year (as opposed to the White Sabbath, Shabbat Shuvah, immediately precededing Yom Kippur).
Tisha B'Av (Hebrew: תשעה באב or ט׳ באב, "the Ninth of Av,") is an annual fast day in Judaism, named for the ninth day (Tisha) of the month of Av in the Hebrew calendar. The fast commemorates the destruction of both the First Temple and Second Temple in Jerusalem, which occurred about 655 years apart, but on the same Hebrew calendar date. Tisha B'Av is never observed on Shabbat. If the 9th of Av falls on a Saturday, the fast is postponed until the 10th of Av.