Moonbows
“Moonbows” as they have come to be called are a lot like normal rainbows. However, they occur less than 10% as often as rainbows. Essentially, the moonbow is just an optical phenomenon caused by light streaming through the atmosphere. That light is then reflected and refracted by water droplets in the air, which then results in the appearance of what seems like a rainbow occurring at night. Some might wonder, why are moonbows or lunar rainbows so rare if it rains and clears up at night just like they can during the day. Basically, the amount of light available even under the brightest full moon is nowhere near the light produced by the sun. Thus, moonbows are often faint and rarely seen. Therefore, you could have one happening nearby but you just cannot see it.