Your questions answered: Why the night sky may be blue and more!

Your questions answered: Why the night sky may be blue and more!

I continue to answer your questions about night photography. I’ll answer what you’ve asked most recently. This time? All about the night sky!

I answered some of your night photography questions previously here and here.

Abandoned airplane, Kansas. I used a handheld light to light paint this airplane during the exposure.

Why are night photos often so bright?

There are several reasons for this. One is that the camera is more sensitive than our eyes at night during a long exposure image. I might set the camera at 20 seconds with a high ISO of 6400, and it’s going to show more than we can see with our own eyes in person.

However, there’s another reason, and it is more mundane. Printing a really dark image doesn’t typically work very well. And let’s face it, most of the time, the photos don’t look great when shared online either.

Why do some night photos look like they are in daylight?

Road Runner's Retreat, CA. "Route 66 Abandoned: Under a Western Moon" by Ken Lee
Road Runner’s Retreat, CA. “Route 66 Abandoned: Under a Western Moon” by Ken Lee

Sometimes, you see them. They are relatively bright, the sky is blue, and you can see the background. They look like strange daylight photos.

Usually, if someone remarks that some night photos look like they are in daylight, they are photos created near a full moon. As we know, the moon doesn’t create light of its own. It’s all reflected light. And that light is almost all reflected from the sun.

It so happens that sunlight often makes the sky blue. And if the moon is simply reflecting that light, it too is going to make the sky look blue.

Night selfie portrait with giant motel sign
Night selfie portrait with giant motel sign

Why does the sky look blue in night photos?

The bluest of the blue night photos are often created when the moon is out. The fuller the moon, the bluer the sky. Why? Because it’s reflecting more of the sunlight. As more of this sunlight passes through our atmosphere, it is scattered in all directions by the gases and particles in the air. This scattering is called Rayleigh scattering. Blue light is scattered the most because it travels in shorter, smaller waves, so we tend to see it the most.

When we set our camera for a very long exposure, it can be more sensitive to light than our eyes during a long exposure, just as mentioned above. And in this case, it can pick up even more blue in the sky than our eyes can see, especially since the camera is sensitive to all colors of the spectrum, unlike our eyes.

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Milky Way, Trona Pinnacles.

Other night skies can look blue too. Sometimes, when the Milky Way is out, the sky might still appear blue even though there’s no sunlight. A true representation of the sky during this time is closer to black or really dark gray. However, some photographers might take some artistic liberties and set the White Balance of the camera to a cooler setting, such as 3200 or 3300K. This creates a blue sky, and can be done for artistic purposes. Many night photographers feel they are creating art, and find a slightly blue night sky can look quite pleasing. Other times, the photographer might choose to go with a black sky because it is more accurate and might fit the mood of the photo better.

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Double Arch, Arches National Park, Utah. Nikon camera.

Bonus: Does the Milky Way actually look like it does in most photos?

Find out more about this interesting question by reading this short article about how the Milky Way appears to us in person.

If you have any more questions, please leave them in the comments! Thanks!