What’s the only feast that falls on a new moon? Feast of Trumpets! The Feast of Trumpets always begins on Tishrei 1, the beginning of the seventh month on the Hebrew calendar. It’s always marked by a new moon.
Genesis 1:14 tells us:
“Then God said, ‘Let there be lights in the expanse of the heavens to separate the day from the night, and let them be for signs and for seasons and for days and years;'”