There are several places in Scripture where the moon is described as a “light,” even though, as we know, the moon does not produce any light of its own. Genesis 1:16 describes the creation of the sun and moon this way: “God made two great lights—the greater light to govern the day and the lesser light to govern the night.” Other references to the moon as a light include Isaiah 30:26; Ezekiel 32:7; and Mark 13:24.
Describing the moon as having light is a matter of semantics. The moon is a luminary, even if the light it brings to the night sky does not actually originate with itself. Saying that the moon is a light is an example of phenomenological language, which people use all the time. It is not improper to speak of the “sunrise,” even though the sun does not actually rise (rather, the earth rotates on its axis). In the same way, it is acceptable to designate the moon as a light source. That’s what it appears to be from our perspective. True, without the sun the moon could not function as a luminary, but Genesis 1 does not posit that it would. The two heavenly bodies were created together and described together.
As for the phrase to rule the night in Genesis 1:16, this is an idiomatic expression that simply means the moon is the dominant nocturnal luminary. The fact that the moon is sometimes visible in the daytime sky in no way negates the fact that it dominates the nighttime sky.
The Bible’s description of the moon as the “lesser light” is not meant to classify the moon as a light source similar to the sun. The language is an accurate description of the comparative luminosity of the moon and the sun. The meaning is that moonlight as it reaches the earth is less bright than sunlight, a fact that we all acknowledge.
We do not require the weatherman on TV to use scientifically precise terminology when chatting about the forecast—we do not get confused if he mentions a “sunrise” or “sunset,” even though those are not the technical terms for what’s actually happening in the solar system. We are comfortable with the use of phenomenological language, and we should be able to recognize it in Scripture. God communicated to humanity in a way we could understand and appreciate. The moon does shine, albeit with reflected light, so it is entirely appropriate for the Bible to speak of the moon as a “light.”