Moonbows, also called moon rainbows or lunar rainbows, are rainbows made by the Moon’s rays instead of the sun’s. Moonbows are different from other kinds of rainbows because of this.
Moonbows, also called moon rainbows or lunar rainbows, are rainbows made by the light of the Moon instead of the sun.
This rainbow is like a solar rainbow, except that the light source is not the sun. Instead, it is made when light is mirrored in water droplets in the air, like when it rains or when water falls from a waterfall. They are always on the other side of the sky from the Moon, which can be confusing when the Moon moves across the sky. Moonbows have been seen since around 350 BC when Aristotle wrote about the weather. Rainbows on the Moon are much harder to see than rainbows during the day because the surface of the Moon reflects much less light.
Because of this, it is much harder for the human eye to tell the colors apart in a moonbow because the light is usually too dim to make our eyes’ color sensors work. Because of this, it is much harder to see colors in a moonbow. So, moonbows look white to the human eye, but their real colors come out when they are photographed with a long enough exposure.
The best time to see a moonbow is when the Moon is full or very close to full, and there are no clouds in the sky.
Moonbows can only be seen when the Moon is very close to the horizon (less than 42 degrees, and better, even lower) and the night sky is very dark. But because the sky isn’t completely dark when a full moon rises or sets, moonbows can only be seen two to three hours before dawn or two to three hours after sunset. And it goes without saying that there must be rain or mist droplets in the sky facing the Moon.
Because of these things, moonbows are much less common than solar rainbows. They only happen 5–10% of the time, as often as normal rainbows do. At high latitudes in the winter, when the sky is darker and it rains, moonbows can be seen when the full Moon rises. This is because the Moon and the clouds are in the right place.
The size of the water drops in the air greatly affects how the colors look. When the water drops are smaller, the colors will look less bright.
Rain isn’t the only thing that can make a moonbow. Spray, fog, or mist can also cause them. In the United States, you can find these bows near rivers like Niagara Falls in New York, Yosemite National Park in California, and Cumberland Falls near Corbin in Kentucky.
Spray moonbows are another famous thing to see at Victoria Falls, which is on the border of Zimbabwe and Zambia.
How do you recognize a moonbow?
As was already said, moonbows can only be seen for about three days around a full moon and only against a dark sky near the end of the evening or just before dawn. When the Moon is at its largest and lowest in the sky during the summer at middle latitudes, this is the best time to see a moonbow.
At other times of the year, moonbows may only last for about an hour. Keep an eye out for a faint moonbow whenever it rains when the Moon is bright and in its dying phase. A few colors will be visible, and if you set up a steady camera, you should be able to get good pictures of them.