Moonbow

Moonbow, also known as the lunar rainbow, white rainbow and feelybow, is an optical illusion that can be seen in the darkness of the night. Moonbow is just a rainbow formed from the light reflected from the moon. Moonbows were first mentioned by Aristotle in 350 BC.

How are moonbows formed?

Moonbows are formed in the same way rainbows are. The light reflected from the moon enters the water droplets. Upon entry into the water droplet, the ray of light is refracted(bents or deviated from its original path on travelling from one medium to another) and dispersed(splitting of white light into its component colours on refraction) into seven visible colours. Upon striking the back of the droplet, the light will be internally reflected if it strikes the back of the droplet at an angle greater than 48 degrees. If the light strikes the back of the droplet at an angle lesser than 48 degrees, it will just pass through the back of the droplet. The internally reflected light is refracted again as it leaves the droplet. Violet light bends the most and emerges at an angle of 40 degrees and red light bends the least and emerges at an angle of 42 degrees. All other colours leave the drop at angles between 40 and 42 degrees. Moonbows often appear white despite colours being there because the light reflected from the moon is far less than that produced by the sun and the less bright light from the moon cannot activate the cone colour receptors of the human eye. However, the colours of a white moonbow can be seen through long-exposure photography.

CONDITIONS:

• The moon must be behind the observer.

• The moon must be low in the sky – no more than 42 degrees above the horizon.

• The moon must be nearly at its full phase.

• The sky must be dark.

• The source of water drops must be opposite to the moon.

SOME OF THE BEST LOCATIONS TO SEE MOONBOW: Some of the best locations to see a moonbow include Yosemite National Park in California, Cumberland Falls State Resort Park in Kentucky, Victoria Falls between Zambia and Zimbabwe in Africa, Waimea in Hawaii, and Plitvice Lakes in Croatia.

REFERENCES:

* https://scijinks.gov/rainbow/

* https://www.metoffice.gov.uk/weather/learn-about/weather/optical-effects/rainbows/moonbow#:~:text=A%20moonbow%20(sometimes%20known%20as,faint%20and%20very%20rarely%20seen.

* https://www.wonderopolis.org/wonder/how-rare-is-a-moonbow

* https://www.livescience.com/30235-rainbows-formation-explainer.html

* https://dbpedia.org/page/Moonbow

* https://global.canon/en/technology/s_labo/light/001/02.html

* https://www.physics.utoronto.ca/~jharlow/teaching/everyday06/reading19.htm