Parshat B'Reishit - 5767
In 1:16 the Torah describes how the sun, moon and constellations were created. The Torah calls the moon and sun, "את שני המאורות" and then again calls the moon, "את מאור הקטן".
Rashi goes into a nice explanation using the midrash to describe how the moon complained that they were created equal (moon and sun) but they cannot function like that, so Hashem shrank the moon and that is why the sun is call "מאור הגדול" and the moon is called "מאור הקטן".
But there is a fundamental question here. Why is the moon called a Maor at all? Maor is a source of light and the moon, as we all know is a big rock. It does not shine forth any light of its own, rather the light we see is simply a reflection of the light from the sun. So why is the moon referred to as a source of light?
I think it is related to the sphere of influence. For example, When a rebbe teaches a student, he is sometimes referenced as a father, as his sphere of influence is similar to that of a parent and if the student learns and follows the rebbe, the influence can change the character of the relationship to that of a parent and not just a rebbe.
The moo n shines forth no light of its own. Yet it reflects the light of the sun, to the point where it can light up the night sky. The moon is receiving the influence of the sun and has made itself subservient, in a way, to the leadership of the sun, which is also described in the midrash Rashi describes.
Because the moon accepted the leadership of the sun and dedicated itself to the influence of the sun, it is described as a מאור even though technically it is not.