Where to See a Night Rainbow!
What is a moonbow? It’s a night rainbow around the Moon! That’s right—not all rainbows happen during the day. See where to find a moonbow, how this lunar rainbow is formed, and some stunning photos of moonbows.
What Is a Moonbow?
Just like a solar rainbow, a moonbow or lunar rainbow appears as an enormous arc in the sky when moonlight is refracted through water droplets in the air. Moonbows are much less intense than solar rainbows since the Sun produces much more light. They usually look spooky-white rather than the well-known set of rainbow colors. All of the colors of the spectrum are actually present in a moonbow, but because moonlight is much less intense than sunlight, our eyes have trouble picking up the various colors. (If you’re a photographer, the colors of a moonbow will show up in long exposures or on high-speed film.)
The size of a moonbow depends on the Moon’s height in the sky: the lower the Moon, the bigger the moonbow. The largest moonbows occur when the Moon is within only an hour of rising or setting.
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How Rare Is a Moonbow?
A moonbow is a much rarer occurrence than a solar rainbow. In order for a moonbow to appear, a few things need to happen:
- The Moon must be in or near its brightest phase (full) and be unobstructed in the sky.
- Water droplets must be present in the part of the sky opposite the Moon. Water droplets in the air can come from a recent rain shower, a nearby waterfall, or even the spray produced by the crashing waves on a shoreline.
- The Moon must be low in the sky—no more than 42 degrees above the horizon—so the night sky is very dark.
If all of these things happen together, there’s a chance that a moonbow will appear! The full Moon is nearest the horizon when it’s rising or setting, so look for a moonbow in the hours after sunset or before sunrise.
Where Can You See a Moonbow?
- The best days to see moonbows are near the Full Moon when it’s low in the sky, ideally within 2 or so days on either side of the full Moon. Find out: When is the next full Moon?
- The best time to see moonbows is a couple of hours after sunset (or, before sunrise).
- Similar to a regular rainbow, you must have the moon behind you when you look for a moonbow.
There are certain places where you are more likely to see moonbows.
- Hawaii is certainly a popular place to spot a moonbow, given its many waterfalls and tropical rain.
- In the U.S., a reliable spot for moonbows is Cumberland Falls in Kentucky, which has a 168-foot tall waterfall.
- Outside of North America, a famous place is Victoria Falls, on the border between Zambia and Zimbabwe.
Essentially, you need large waterfalls that produce a lot of mist; most waterfalls don’t produce enough.
Moonbow during the night above Staffin Bay, Isle of Skye, Scotland. Credit: Lukassek/Shutterstock.
Have you ever seen a moonbow? Let us know in the comments!
Bob Berman
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i saw a moonbow years ago riding a motorcycle just north of eudunda in south australia
I saw a moonbow above the ocean in Topsail Island, North Carolina. It was the first and only time I have ever seen one. Our family was gathered on the ocean-front balcony of the condominium we were renting to watch July 4th fire works over the ocean just after sunset when the moonbow appeared. It was a very special experience.
While returning home from working evening shift on a winter night...there it was...with moon shine reflecting on the snow too!!
I have seen the moon with a full ring around it. I don’t think it was a moon bow, but it sure was neat. Northeast Missouri.
I saw a moonbow last night in Cumbria, Uk
I see other comments about Hawai'i here. My moonbow viewing was also in Hawai'i. It was Summer Solstice 1998 and we had a potluck celebration in South Kohala on the Big Island. There was a misty not-quite-real-rain drifting in from the ocean. I went outside to enjoy the twilight, facing West toward the water, and the Full Moon rose behind me, shining into the mist. There was a brilliant, exquisite bow, every color perfectly visible but silvery, instead of the usual warmth. I went in to share the news, and a couple of people came outside to see. We watched for a good half hour until finally the Moon rose high enough that the colors faded. It was a one-of-a-kind memory that I've always treasured. Thanks for this article.
Sailing from Hawaii to California I experienced a full arc moon bow. Very bright night. An amazing site. The dolphins following the boat were pretty nice also.
I was living on Oahu in Makiki on the 8th floor and I was looking west at the Downtown Honolulu city lights. We were sitting on the lanai having dinner and could see that it was raining down there, but when the Moon rose (which would have been to our backs) we saw an incredible specimen of a Moonbow. It was mostly purple but we could even see all of the other vivid colors of white, pink, green, purple and blue...it was A MAZE ING!
Thank you for asking this question, it brought back a wonder memory!
I had always wondered about this, and as I was riding over Rocky Mt. National Park on my way home to Grand Lake via motorcycle, about 9:30 PM, on a mid-August night in 1985, a rain blew in from the West and the full moon shined down from the East. A full Moonbow lit the park just below Fall River Pass. Incredible. There are no words to describle the beauty. About four cars had stopped to watch. I stayed until it faded and continused down the mountain. Once in the switchbacks, I rode into the rain and out of it again several times. I should be so fortunate to see another.
Moonbows are amazing. I observed one as a teen during a camping trip at Pohoiki, Hawaii, 1977. It was shimmery white and it extended over the entire bay, a complete moonbow. It was beautiful and it's memory has never left me.
