Description:

The following shadow experiment was performed using various models of craters, mountains, domes and rilles. After each model was set down on an adjustable table with a degree-protractor for reading sun angles (see FIG 1), the table was then moved through various degrees to direct sunlight (with exception to the conic crater model), and an overhead photograph was taken. Each adjustment was recorded to see how the shadows behaved in accordance with each changing sun angle.

FIG 1 - Experiment setup

Each model was so placed initially on the table to point directly at the Sun. The protractor reading was set at 0 degrees to start off with, and after a photograph was taken, the table was then adjusted to the next degree, followed by a photograph again...etc. Note, for each photograph, the camera at all times remained perpendicular to the plane of the model, and only slight adjustments of the table horizontally rightwards had to be made to counteract for movement of the Sun across the sky (in reality, due to the rotation of the Earth from a Northern Hemisphere perspective). As each model (photograph & reading) took about an hour in length for the sun angles covered, the horizontal movement maintained the alignment of shadows -- from initial to final degree reading -- looked relatively the same throughout.

CRATERS:

Shadows in a simple bowl-shaped crater

Shadows in a conic-shaped crater

Unlike the previous bowl-shaped crater (and all subsequent lunar features covered in this experiment) that used direct sunlight, shadows in the above conic-shaped crater were produced using a simple halogen lamp. Note here that as the shadow gets larger as lower angels are reached, the interior of the crater receives some illumination. This is not entirely due to internal scattering of light from the sunlit wall of the crater, but rather dim, ambient light scattered off the walls and ceiling of the room in which the photos were taken. On the Moon, however, these shadows would be totally black, with only some back-scattering of light into the shadows (mostly at higher sun angles) as it reflected off, say, rocks, boulders, undulations and dust particles from the sunlit slope side.
 

Shadows in a complex-shaped crater

The above model was shaped so as that the central peaks stayed in view for as long as possible before the, somewhat, larger shadows encroached upon them from the right. Note the tiny dot of light on the central peak's tip (in angle 3-degrees), and how it's shadow can just be seen on the main crater's left ridge.

NB: For a more thorough interpretation of shadows in craters, please see Jim Mosher's LTVT link here.

MOUNTAINS:

Shadows across mountains -- round, peaked and flat

DOME:

Most domes on the Moon have relatively shallow slopes with ratios in Height (HT) to Base Diameter (BD) starting off at around the 1:40s that climb predominantly higher; for example, Archytas Ar 2 (56.521N, 2.71E) with HT = 275m and BD = 11000m has a ratio of ~ 1:41, while its nearby neighbour Ar 1 (55.71N, 0.71E) with HT = 70m and BD = 33000m has a ratio of ~ 1:470. As a result, shadows really don't show up around domes until very low sun angles are reached, and the dome is actually approaching very close to, or on, the terminator itself. In the above model the ratio is only ~ 1:11, so the shadow appears relatively quicker than normal, however, as the model was also built upon a curved surface to simulate that of the moon's, the resultant setup produced a more dramatic effect than would be expected for a real lunar dome.

RILLES AND FAULT:

Shadows across two rille types -- linear and sinuous, as well as a straight fault

Upto 37 images for each sun angle down to 1 degree were taken. however, as there wasn't much change in the shadow between 33 degrees and 6 degrees (that is, from angles 32 degrees to 7 degrees), these have been left out.