There is such a thing as a rainbow at night. It is called a lunar rainbow. I once saw one, without understanding what it was. How could it be, I wondered?
Finally, I saw a picture of one, an arched one, not the round ring around the moon kind. I knew.
Some people are like rare lunar rainbows. In the dark night, they collect secondary light and reflect it back as a full spectrum of color.
I have seen them. Perhaps it was you? I know.