5.6 Why do the astronauts cast shadows of different lengths?

IN A NUTSHELL: Because the Moon’s surface isn’t perfectly smooth and level. If there’s a slope, a bump or a hollow in the ground, the astronaut’s shadow will follow its shape and vary its length accordingly. The same happens on Earth.

THE DETAILS: In some Apollo photos and movies the shadows of the astronauts have different lengths; an example is shown below. Moon hoax proponents such as David Percy argue (for example on the Aulis.com website) that this is because the fake astronauts stood at different distances from the overhead studio lights.

A frame from the Apollo 11 movie camera shows that the shadows of the astronauts have different lengths.


However, Percy’s explanation doesn’t hold water, because in the image above the astronaut who is closest to the hypothetical spotlights (as indicated by the direction of the shadows) has the longest shadow, whereas in real life objects that are closer to an elevated light source cast shorter shadows. This can be demonstrated easily by standing at various distances from a streetlight.

The correct explanation for the different shadow lengths is that the surface of the Moon is uneven and has all sorts of slopes, rises and hollows, which sometimes aren’t easily detected in photographs because there are no familiar items for visual reference. These differently sloping portions of the surface alter the length of any shadow that falls onto them. The same thing happens on Earth.

This can be shown by building a model of the lunar surface and lighting it with a single distant spotlight (simulating the Sun). It turns out, perhaps surprisingly, that a model astronaut placed even in a shallow depression casts a shadow which differs greatly in length from the one cast by another identical astronaut standing on level ground, as shown below.

A model shows how even a small hollow changes shadow lengths. Credit: PA.


In the Apollo 11 image taken from the 16 mm film footage, the astronaut on the left is simply standing in a slight hollow of the ground, which shortens his shadow. This hollow isn’t detectable in the picture, but it’s definitely there: it’s revealed by the curved shadow of the flagpole in photo AS11-37-5473 (shown cropped for clarity below).

Detail of photo AS11-37-5473 (Apollo 11).


What’s certainly surprising is that Percy is a member of the British Royal Photographic Society and has received several awards for his work as cameraman. In theory, therefore, he should be quite knowledgeable about lighting and the behavior of shadows on uneven ground.