The moon was made on the fourth day of creation. The moon rules the night and is for signs and seasons.

”And God said, Let there be lights in the firmament of the heaven to divide the day from the night;
and let them be for signs, and for seasons, and for days, and years: And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so. And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also. And God set them in the firmament of the heaven to give light upon the earth, And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good. And the evening and the morning were the fourth day.

Genesis 1:14

The Feasts of the Lord are seasonal, kept according to the new moon (except the Sabbath).

“And the LORD spake unto Moses, saying, Speak unto the children of Israel, and say unto them, Concerning the feasts of the LORD, which ye shall proclaim to be holy convocations, even these are my feasts. Six days shall work be done: but the seventh day is the sabbath of rest, an holy convocation; ye shall do no work therein: it is the sabbath of the LORD in all your dwellings. These are the feasts of the LORD, even holy convocations, which ye shall proclaim in their seasons."
Leviticus 23:1

“He made the moon also to serve in her season for a declaration of times, and a sign of the world. From the moon is the sign of feasts, a light that decreaseth in her perfection. The month is called after her name, increasing wonderfully in her changing, being an instrument of the armies above, shining in the firmament of heaven; The beauty of heaven, the glory of the stars, an ornament giving light in the highest places of the Lord.”
Ecclesiasticus 43:6

Israel had a dinner for the New moon and sacrificed unto the Lord.
"So David hid himself in the field: and when the new moon was come, the king sat him down to eat meat. And the king sat upon his seat, as at other times, even upon a seat by the wall: and Jonathan arose, and Abner sat by Saul’s side, and David’s place was empty. Nevertheless Saul spake not anything that day: for he thought, Something hath befallen him, he is not clean; surely he is not clean. And it came to pass on the morrow, which was the second day of the month, that David’s place was empty: and Saul said unto Jonathan his son, Wherefore cometh not the son of Jesse to meat, neither yesterday, nor to day? And Jonathan answered Saul, David earnestly asked leave of me to go to Bethlehem: And he said, Let me go, I pray thee; for our family hath a sacrifice in the city; and my brother, he hath commanded me to be there: and now, if I have found favor in thine eyes, let me get away, I pray thee, and see my brethren. Therefore he cometh not unto the king’s table.”
1 Samuel 20:24

The entire world will honor the new moon law, a sign for the feasts to be kept.

“And it shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the LORD.”
Isaiah 66:23

Convocation - a large formal meeting of people (such as church officials)
* Read: Psalms 81:3, Isaiah 66:23, Amos 8:5*