During Kiddush Levanah, a brief prayer is recited, that God "fill the defect of the moon, that there should be no more diminution thereof, and that the moon's light be like the sun's light and like the light of the Seven Days of Creation..." [trans. mine]
What does this mean? Are we really praying that the moon stop its phases and outshine the sun? And how will we be able to keep the calendar if there's never a "new moon"?