How much does moonlight affect astrophotography?

Question

I know the Moon acts like natural light pollution, but how much it affects astrophotography seems to vary. Can you still get good night-sky photos when the Moon is up, especially if you're photographing nearby objects in the sky such as satellites? I’m using a Nikon D3400.

user15871 · Accepted Answer

How much the Moon affects the ability to photograph other astronomical objects is highly variable based on many factors:

The phase of the Moon. A full moon washes out much more of the sky than a thin crescent.
The relative positions in the sky of the Moon and your target object. The closer in the sky the moon is to your target, the more pronounced the effect of the Moon's light.
The amount of water vapor and particulate matter in the atmosphere. The more things there are in the air that disperse the Moon's light, the greater the effect the Moon's light will have on your ability to separate your target's brightness from the brightness of the sky.
The altitude at which you are located. Higher altitudes have less of the densest parts of Earth's atmosphere, and all of the moisture and particulate that may be in it, between the camera and astronomical objects, so there's less of the Moon's light dispersed over the entire sky.
Atmospheric turbulence can make it more difficult to see dimmer astronomical objects.
The brightness of your target object. It's practically impossible to image a fourth magnitude object with a full moon anywhere in the sky. On the other hand, It's very easy to capture a very bright object, such as Venus which can be as bright as magnitude -4.7. In fact, at magnitude -4.7, Venus can be imaged when the Sun is in the sky. Just be careful not to point your lens so that the sun is in the frame or in the image circle projected by the lens but outside the frame.

Two example images:

A very thin crescent Moon and a few bright stars above the horizon shortly after sunset on 13 March, 2013. If one looks closely one can just make out Comet Pan-STARRS almost lost in the atmospheric haze closer to the horizon.

_{For more details about this image, please see this answer to How can I capture earthshine?}

An almost full Moon completely blows out and creates numerous flares and ghosts at exposure levels needed for much dimmer astronomical objects.

_{For fuller details about this image, please see this answer to Can you photograph the milky way with a full moon out?}

How much does moonlight affect astrophotography?

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