What is a Moonbow?



Sunlight Reflected Off the Surface of the Moon

A moonbow (lunar rainbow) is an interesting phenomena that occurs when the light from the Sun gets reflected off the surface of the Moon. A moonbow forms when the reflected light from the Moon is diffracted when interacting with water droplets suspended in a rain cloud or the mist of a waterfall. Unlike the colorful rainbows produced by the sun´s light in a rainy day, moonbows appear white due to the loss of brightness which is not able to activate the cone color receptors in the eyes.

Moonbows are most easily observed on a dark night, preferably far away from any source of city lights. A moonbow is created by the indirect light from the Sun via Sun-Moon-moonbow. This produces a decrease in light intensity, producing moonbows which are almost imperceptible. In addition, the loss of intensity could be further eclipsed by added light luminosity, depriving the possibility of witnessing a moonbow.

The best time to observe a moonbow is on a full moon night. A full moon is essential in order to reflect plenty of light necessary to create the phenomenon. The Moon must be positioned in a 42° angle, or less from the horizon. Moonbows usually appear in the part of the sky opposing the Moon with the viewer behind the Moon. It is essential that a dark night, full Moon and the Moon situated at a suitable angle be present for a moonbow to be appreciated.

Moonbow Created by the Rising Mist from the Waterfall


How is a Moonbow Formed?

The light reflected from the Moon creates a faint moonbow when interacting with the mist rising from the waterfall. Sometimes, a colorful arc moonbow can be witnessed when the full Moon is shining above in the sky on a clear cloudless night, allowing a considerable amount of moonlight to be diffracted off the droplets in the air.

The waterfall provides the medium against which the light reflected off the moon will interact in order to produce a moonbow. The best way to observe a moonbow is to situate yourself between the medium (mist) and the Moon with the full Moon behind you.

Moonbow and Aurora Borealis

Stephane Vetter
Stephane Vetter

Moonbow in the Northern Latitudes

If you happen to be in the northern latitudes contemplating a moonbow with clear skies and a bright full Moon, the phenomenon may be accompanied by other natural phenomena, such as the glowing lights of the aurora borealis curtains with their characteristic green color in the background sky, such as in the photograph taken in Iceland.

A moonbow is produced by reflection, refraction and dispersion of the light coming from the Moon and interacting with the mist or falling rain. A moonbow contains the colors of the spectrum; however, in not too intense full moon nights, only a white moonbow will be perceived. Its color varies from plain white to grayish white. Other names with which a moonbow is known include moonrainbow, nightrainbow, lunar rainbow and white rainbow.

Moonbow at Yosemite National Park

Yosemite National Park
Yosemite National Park

Famous Places to Watch a Moonbow

Moonbows are fascinating phenomena to watch. Moonbows are more rare than rainbows created by the Sun, as they depend on more factors other than just sunlight. The most usual places to witness a moonbow are the ones that meet the required conditions for them to be seen, such as a waterfall. There are famous places in which mooonbows are known to become visible, including Cumberland Falls and Yosemite National Park in the U.S. Victoria Falls in Africa and Waimea Canyon in Hawaii.

Cumberlands Falls, Kentucky claims to be the only place in the Western Hemisphere where a moonbow can be predicted for observation.

Additional Data about Moonbows

Other names with which a moonbow is known include: lunar rainbow, white rainbow and space rainbow.

For a moonbow to occur there must be good weather conditions with clear skiesand a full Moon; however, a clear moonlit night can be good enough to reflect enough sunlight to show a moonbow.

A colorful moonbow is most commonly seen during the fall and winter season when the air in the atmosphere is drier.

Long exposure cameras can capture the colors of a moonbow

More by this Author

  • What Elements Make Up the Earth’s Atmosphere?

    The atmosphere is a thin layer of gases surrounding the surface of the Earth. The gases composing the atmosphere are distributed in a layer of approximately 150 km (93 miles). The atmosphere is divided into different...

  • Basic Structure and Formation of Snowflakes

    Snowflakes are formed from aggregations of ice crystals. Ice crystals from in the clouds when they freeze around tiny particles of dust in the atmosphere. The shape of a snowflake is determined by a variety of weather...

  • How Does a Volcano Form?

    Volcanoes are natural features of the Earth's lanscape. Volcanoes form from the natural internal forces acting inside the Earth. Mos volcanoes form at the boundaries of tectonic plates either in the ocean or on land....

Comments 12 comments

Marturion profile image

Marturion 4 years ago

Interesting. I can honestly say I've never seen a moonbow. I'll have to look into this some more.

unvrso profile image

unvrso 4 years ago from Mexico City Author

I agree! This type of phenomena is interesting! If you live close to a waterfall, you might have to wait until you see a full Moon in the sky, along with a clear night. This might allow you observe a moonbow.

bankscottage profile image

bankscottage 4 years ago from Pennsylvania

Nice Hub. Thanks for answering my question.

I visted Cumberland Falls near Corbin, KY but not sure that I saw one.

unvrso profile image

unvrso 4 years ago from Mexico City Author

A moonbow can best be seen two days before or two days after a full moon. This is because the full moon can reflect more intensely the light from the sun. On this page are the dates when a moonbow is more likely to be seen in Cumberland Falls:


bankscottage profile image

bankscottage 4 years ago from Pennsylvania

Thanks. I was only visiting, but I'll pay more attention to a full moon if I go back. I thought they said the only other place you can see a moonbow is in Australia or New Zealand, but I see you have a picture from Yosemite. You also say they can be seen in Hawaii and Africa. I am more likely to go to Hawaii and visit Wiamea Canyon than go to Africa or even back to Corbin for that matter.

unvrso profile image

unvrso 4 years ago from Mexico City Author

The places I mentioned are the most renown places in the world where moonbows are known to occur, however, a waterfall or a light rainy night is likely to produce a moonbow, moreover, you can make a moonbow if you wait for a full moon and clear skies, then make a drizzle with a water hose. For this to occur, you have to be between the full moon and the drizzle, with the full moon behind the observer (you).

Vokes 4 years ago

We were camping in Caerfai Bay, Pembrokeshire, Wales and about 10 days ago saw a moonbow. It was white and could be seen with our backs to the moon. The moon was just bigger than a half moon, there was a little drizzle in the air and it was a clear, dark night. We had never heard of a moonbow and it was a fantastic sight. This was a natural phenomenon, in the sky (like a rainbow) and not made by a full moon, waterfall or in one of the main places to view moonbows.

That's the wonder of Wales for you.....

unvrso profile image

unvrso 4 years ago from Mexico City Author

That's all you need! A drizzle and the Moon behind the observer. Sufficiently dark and nothing outshining the moonlight.

Abdul Wahabone profile image

Abdul Wahabone 4 years ago from Yanbu Al-Bahar, Al Madinah, Saudi Arabia

such an informative hub, i didn't know about moon-bow, thanks.........

unvrso profile image

unvrso 4 years ago from Mexico City Author

Thanks for taking the time to visit and commenting on this hub, Abdul Wahabone.

Hawaii 3 years ago

Some time ago I was driving up to Mount Haleakela on Maui at night. I saw the most amazing moonbow. I pulled to the side of the road because I was afraid of causing an accident (the moonbow was so amazing that it captured all your attention). Everyone was pulling to the side of the road. I live at 3,800 feet on Haleakala, but I doubt I will see such a moonbow again. It was a once-in-a-lifetime experience. BBMaui

kasia 2 years ago

Why do moonbows form???

Submit a Comment
New comments are not being accepted on this article at this time.
Click to Rate This Article