As אותות, the luminaries make us aware of God’s power and his management of the world.
As מופתים, the luminaries not only inspire belief but convince and influence Man’s power of self-will.
By means of the luminaries, מועדים are determined. (A מועד is a fixed place and time to meet)
In general, the luminaries serve for all Mankind as אותות. The stars, the regulated cycles of the sun and the moon, declare “There is a God!”
At certain moments in history the luminaries (or the sky), have served as signs of God’s promises:
After the flood, God showed Noah the rainbow in the sky and called it an אות of the covenant God was making between Himself and all of Mankind.
When God told Avraham that he was going to be the father of a nation, He showed him the stars and said “so will be your children”.
When Israel was to leave Egypt, Moshe was shown the moon and God told him that the moon is a symbol of the Jewish people’s ability to struggle through the darkness and emerge to the light. (see some very inspiring words about קידוש החדש on page 24)
God appointed מועדים, times for Israel to come before Him and in union with His Torah, to refresh Israel’s memory of its redemption and being made holy. These holidays are connected to the cycles of the luminaries so that Israel bears in mind that the same way God rules over nature so does He rule over history.
Beraishis 1:14-19 Pages 23-24