<img class="styles__noscript__2rw2y" src="https://dsx.weather.com//util/image/w/moonbow-arrow-primary-jullie-powell-9jul16.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0" srcset="https://dsx.weather.com//util/image/w/moonbow-arrow-primary-jullie-powell-9jul16.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 400w, https://dsx.weather.com//util/image/w/moonbow-arrow-primary-jullie-powell-9jul16.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 800w" > A moonbow is visible during a late-night thunderstorm in Shepherd, Montana, on July 9, 2016, highlighted by the faint gray arrows. (Jullie Powell Photography) (Jullie Powell Photography)

A rare moonbow was captured in photos over the weekend in eastern Montana.

Photographer Jullie Powell shared photos of the rare phenomenon with The Weather Channel as she watched a thunderstorm in Shepherd, Montana, on Saturday.

The moonbow, which appeared just before 11 p.m., was illuminated by lightning. If you look at the photo below close enough, you can almost make out an extremely faint secondary moonbow to the left of the main bow.

<img class="styles__noscript__2rw2y" src="https://dsx.weather.com//util/image/w/moonbow-lightning-jullie-powell-9jul16.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0" srcset="https://dsx.weather.com//util/image/w/moonbow-lightning-jullie-powell-9jul16.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 400w, https://dsx.weather.com//util/image/w/moonbow-lightning-jullie-powell-9jul16.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 800w" > A moonbow is visible during a late-night thunderstorm in Shepherd, Montana, on July 9, 2016. (Jullie Powell Photography) (Jullie Powell Photography)

A half-hour later, Powell photographed the spectacular scene of a distant thunderstorm lit by lightning, with a short moonbow overlaying the rain shaft near the horizon.

Moonbows, also known as lunar rainbows, are the dimmer cousin of more common daylight rainbows, made possible from the refraction of raindrops by moonlight, rather than sunlight.

Moonbows are so rare because moonlight is not usually bright, and the alignment of conditions needed for them don't happen often.

According to Atmospheric Optics , a bright near-full moon must be less than 42 degrees above the horizon, illuminating rain on the opposite side of a dark sky.

Another recent moonbow was captured in western Iceland on a late November 2015 night.

The most dependable places to see moonbows are large waterfalls, thanks to the plentiful supply of water droplets from the waterfall's spray.

One spectacular example was captured in a timelapse from Victoria Falls, Zambia .

Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7.