rainbow to occur the conditions have to be just right. The moon has to be a full moon, which only happens once a month. The light of a full moon is a faint light, so the lunar rainbow will never be as prominent as the solar rainbow. Additionally, the full moon has to be either rising or setting. A naval officer, V. E. Mikkelson, described his reaction when he learned that the spotlight he saw was actually a lunar rainbow: The strange phenomenon I was viewing was a rainbow generated by moonlight! It was being formed by moonlight passing through rain trailing from one of the fluffy cumulus clouds. The rainbow was composed of the standard colors, but they were softer and paler than those generated by direct sunlight. They were what I can only describe as pastel. I was truly entranced. I have seen many of nature's beauties, but none have ever impressed me so powerfully
             ...