Sundown starts Yom Teruah, the Day of Trumpets. This is a holiday from Leviticus 23 that symbolizes/prophecies the return of the Messiah. Those who believe in Jesus, aka Yeshua, really ought to be keeping these days and learning what's next in the plan of salvation.

For the Lord Himself will descend from heaven with a shout, with the voice of the archangel and with the trumpet of God, and the dead in Christ will rise first.
(1Th 4:16 NAS95)