Most of us will not believe this. In fact, we never seem to have given any thought to it because it is very uncommon and very faint and seen only in some places in the world. But the truth is it exists and had been photographed be the dedicated enthusiasts.
What is light exactly? No one knows for sure. The observations about its behavior are explained by resorting to theories. Some of its properties are explainable considering it as a wave and other properties by considering the light as bundle of particles called photons.
In fact, in the realm of subatomic and galaxy scale, the entities behave in very unpredictable manner. Our mind which is attuned to the events happening in the middle scale, our comprehension fails to explain the phenomena occurring at the two extremes Rainbow is formed when the water droplets in the air hanging after the rain split the sunlight which is a mixture of 7 colors which we humans can see with eyes. It takes the shape of banded arc of individual colors. The phenomena is related to refraction. The different colors bend at different angles while entering a denser medium from a thinner medium. The red color with highest wavelength bends least and violet which have lowest wavelength bends the maximum thus representing the the two extremes of spectrum with rest of the colors following the famous “VIBGYOR” sequence. If we go towards lower wavelengths than violet, we enter into ultraviolet region which has higher energy. Going more and more towards lower wavelengths takes us into X-rays. On the other hand, if we go beyond red color we have lower and lower energy radiations beginning with infrared and going towards radio waves.
Moon as we know is not a star and hence does not have its own light source. It acts like a mirror reflecting the light falling from sun on its surface. This gives us the illusion that moon has its own light.
So, the light moon reflects is exactly of same composition as the sunlight. In fact it is sunlight but it is very weak. In fact, its luminosity is very feeble. But keen observers are not dissuaded and have photographed this feeble but strange surprising phenomena. If you are interested, you can visit the this website to see some beautiful pictures. I have visited some other sites but the photos show the rainbow effected by the waterfall, the rainbow is very low.
Frankly, I came across this phenomena while I was reading “The Hungry Tide” a book by Amitav Ghosh. The book describes the struggle of the people living in Sunderbans delta where life is a constant struggle on day to day basis. There are so many perils like crocodiles, tides, storms, inundations, deluges, the dreaded royal Bengal tigers. Life is strongly tied to the nature as the livelihood is dependent on the nature’s dower in the form of sea food, honey and wax which these people have to snatch from the jaws of crocodiles, tigers and other perils. There are strange phenomena verging on the mythical. In fact myth and reality seem to become one, melt into one another like a twilight zone where light and darkness hug each other and then depart in their usual fashion of exclusiveness of one another. In this book, the phenomena of moon rainbow is described and characters who have been watching the nature very closely see it when sailing in the boat.