Moonbow: Cumberland Falls - Our Campfire Unplugged

Rainbows possess a power that can uplift our spirits and inspire awe as we catch a glimpse of the stunning colors floating across the sky after a rain shower. Imagine being able to see a rainbow at night! In certain conditions, it is possible to see a MoonBow…a lunar rainbow.

My grandfather was particularly good at spotting rainbows. He would always reference my grandmother when he saw one; she had passed years before and this was a very thoughtful and loving memorial to his wife. My son, Jack (who shares his name with my grandfather) also has the special power of spotting rainbows.

Conditions must be nearly perfect for a rainbow to form and be visible. Small droplets of water must be present in the sky and the sun needs to be at about 40 to 42 degrees in the sky to get a good rainbow. In Yellowstone National Park, we saw rainbows daily!

Seeing a Moonbow takes even better fortune!

What is a Moonbow?

A Moonbow, or lunar rainbow, is essentially a rainbow created by tiny droplets of water or mist refracting the moonlight. When a full moon is at the right angle in the sky (40 to 42 degrees) and the sky is very dark it is possible to see a Moonbow.

Where can I see a Moonbow?

Across the globe, there are several places to see a Moonbow.

Niagra Falls – New York
Yosemite Falls – California
Cumberland Falls – Kentucky
Hawaii – numerous falls / check with locals when you visit!
Victory Falls – Border of Zambia and Zimbabwe

These aren’t the only places, but certainly the places where it’s most common.

Three elements are critical to seeing a Moonbow:

Full Moon
Plenty of water flowing over the waterfall
Dark Sky

Niagra Falls

If you’ve visited Niagra Falls, you know immediately which box doesn’t get checked here! Niagra Falls for all it’s beauty and wonder is 100% the definition of light pollution. The falls are lit at night, hotels and tourist attractions emit tremendous light into the night sky and the city of Buffalo is only a few miles away. Visitors are unlikely to see a Moonbow.

Yosemite Falls

Visitors may have greater luck seeing a Moonbow in Yosemite Falls at very specific times of the year. Typically, April through June are the best full moons for potentially catching a Moonbow in Yosemite. During this season the falls are flowing with plenty of water from the snowmelt. The window to see a Moonbow in Yosemite is relatively short, about 15 minutes.

Cumberland Falls

Cumberland Falls located in Corbin, Kentucky is home to one of the most regularly occurring Moonbows in the world! Nestled on the northeastern edge of the Big South Fork National River and Recreation Area, Cumberland Falls State Park offers very dark skies! Park officials created optimal viewing platforms for visitors to witness the power of the lunar rainbow.

Thanks to a central location and close proximity to Interstate 75, Corbin, Kentucky is within 8 hours driving of visitors as far away as Washington, D.C, Baltimore, MD, Chicago, IL, Detroit, MI, Savannah, GA, and St. Louis, MO.

How to see a Moonbow at Cumberland Falls?

From our experience visiting Cumberland Falls, seeing a Moonbow involves a bit of good luck and clear weather. Fortune has favored us on both visits!

Since Moonbows are only visible after sunset, local accommodations are nice to have. We stayed nearby at the Sheltowee Trace Adventure Resort, which is about 5 miles from the state park.

During the summer, Moonbows are visible much later in the night (11 PM to 1 AM or later). Generally about 2 hours after sunset. And during winter hours, Moonbows are visible earlier.

Weather factors into Moonbow visibility. Cloudy skies prevent the moon’s light from refracting from the water droplets. Wind can spread the droplets too far to allow for proper refraction. So, seeing a Moonbow is really a special event!

At Cumberland Falls, visitors can see the Moonbow from the top observation deck. Or for the best viewing, check out the lower platforms a short walk down a number of stairs to the overlook. Be careful, the stairs are NOT lighted, so bring a small flashlight. Arrive early to get the best spot and to let your eyes adjust.

Our first visit was very crowded on the overlook platform while our latest visit was much less crowded and with patience, we had a front-row viewing position within a few moments.

When can I see a Moonbow?

At the risk of stating the obvious, lunar rainbows are only visible after sunset. Typically, the best viewing is available about 2 hours after sunset and then for the next two hours. If sunset is 9:30 PM, then the best viewing will be between 11:30 PM and 1:30 AM. Get a shot of caffeine! The moon needs to be at an angle of 40 to 42 degrees in the sky to refract the best in the mist.

If the night sky is cloudy, your chances of seeing a moonbow decrease.

On windy nights the mist droplets can spread out and make it tough to see the moonbow.

If you don’t see the moonbow, the falls are really cool in the moonlight.

What will the Moonbow Look Like?

To the human eye, it will be a white arch in the pool of the waterfall. It’s not an arch over the falls themselves. Rather an arch below the falls where the mist gathers. The white arch may be faint at times. Sometimes it fades in and out. So you need to let your eyes adjust to the darkness. Sometimes the white arch is pronounced. The key is patience! And realizing witnessing a moonbow is a very special event!

Moonbow calendar

For 2023 the remaining moonbow dates at Cumberland Falls (from the Farmer’s Almanac) are:

September 27, 28, 29, and 30
October 1, 26, 27, 28, 29, and 30
November 25, 26, 27, 28, and 29
December 24, 25, 26, 27, and 28

Are Moonbows Rare?

Yes. Moonbows are fairly rare. Some sources indicate these natural wonders happen about 10% as frequently as rainbows. Catching a moonbow requires a waterfall producing a lot of mist, a full moon, a clear & dark sky, and some good luck!

Distances to Cumberland Falls

Here are the approximate distances and driving times to Cumberland Falls. This park is very accessible to most visitors!

Atlanta – 296 miles (4 hours 30 minutes)
Chicago – 473 miles (7 hours 25 minutes)
Cincinnati – 183 miles (2 hours 50 minutes)
Detroit – 445 miles (6 hours 45 minutes)
Indianapolis – 290 miles (4 hours 30 minutes)
Knoxville – 86 miles (1 hour 25 minutes)
Louisville – 178 miles (2 hours 50 minutes)
Nashville – 205 miles (3 hours 15 minutes)
St. Louis – 440 miles (6 hours 40 minutes)
Washington DC – 570 miles (8 hours 50 minutes)

Helpful Tips and Resources

Advanced planning is critical to a successful trip. Make sure to arrange for lodging. Corbin Kentucky has a number of hotels in town. Cumberland State Park Resort offers a nice lodge-style hotel with a restaurant serving breakfast, lunch, and dinner! The Sheltowee Trace Adventure Resort offers cabins and camping accommodations.

Make sure to bring a camera AND tripod. Your camera will need a longer shutter time to capture the images of the moonbow. This requires your camera to remain perfectly still or you will get blurry images.

Dress for the weather. Remember you will be close to the water so dress warmer than you think you need in the cooler months. In the warm months dress for warm and humid conditions.

Plan to arrive early to secure a good viewing spot. Sometimes it’s really crowded and other times the crowd is lighter. It’s hard to judge. So, give yourself time to park, walk to the falls, and get a good spot. Plan to stand. Unless the crowd is really small, the viewing platform is not really large enough to accommodate folding chairs.

Be considerate of other visitors! Try to minimize the use of your cell phone flashlight (use a red light flashlight, if possible). Keep your flash turned off when taking pictures. Everyone is trying to see the same cool thing. Your flash will disrupt their night vision.

Enjoy your moonbow experience! It’s truly an opportunity of a lifetime.