Sailor moon

This image, showing a sailing boat with its mast aligned perfectly with a half moon, is very popular. It appeared online in 2015 and has been shared countless times as a real photograph. However, it’s a photoshop job and as photograph, it would be almost impossible. Note that there are many similar images being shared as real. It is very likely that they are all photoshopped.

I don’t need any fotoforensic tool to determine this image is not a real photograph. Let’s examine this image from technical and scientific perspective:

It’s possible to take great photographs of the moon, especially with a telescopic lens. There are plenty of real, single-exposure examples out there. If we assume this picture was taken with, say, a 300-800mm telescopic lens, there is one technical challenge: focus. In this picture, both the boat and the moon are in focus. In practice, either the foreground or the moon should be somewhat out of focus.

Next, we will look at the moon phase: the half moon is the first quarter and third quarter moon. We see half of the moon illuminated and half in shadow. The illuminating light obviously comes from the sun. Looking at the picture, the sun should be somewhere “on the right,” and higher in the horizon. The shadows and light conditions in the foreground simply do not match. The boat photo was likely taking during daytime.

Last but not least: all light coming from space has to pass through the Earth’s atmosphere before reaching us. The closer something is to the horizon, the more its light has to pass through air. This has multiple effects on the appearance of a moon this low in the sky. Firstly, our atmosphere passes red light better than it does blue light, so the moon would appear more red, just like a sunset does. Secondly, the shape of the moon would become more distorted as the atmosphere bends light unevenly. It would also be very difficult to get a sharp image of the moon only a few degrees above the horizon unless the atmospheric conditions were particularly good.