How does moonbows produces ?
The Rain bow produces due to sun light reflection and refraction through/on droplet in atmosphere (above earth).
Moon bow is produced due to the same phenomena but instead of sun light, it is moon light i e Moonlight reflection and/or refraction on/in droplets in atmosphere. The effect is prominently found over huge waterfalls where density and height of droplets surrounding and at enough height on Fall exist. Especially on a full moon night it can be nice visible. Of course, moon light is not as intense shining as sun light, however it is visible. Principle of formation is same as Rainbow and visible on the opposite side to the moon with reference to observer