It’s already been demonstrated on this site that there are photographs of the moon taken during Apollo that could not have been taken from Earth. What this page will show is that the photographs and video taken from orbit show another area of complete consistency with the stated record: the location of the lunar terminator.

Terminator photography was a feature of all missions in one form or another, and in longer missions the terminator can be seen to move consistent with that passage of time.

To demonstrate this feature I’ll use the free Virtual Moon Atlas (VMA) software and its downloadable overlays in combination with the records at the Apollo Flight Journal and Apollo Lunar Surface Journal, and the positions of Apollo photographs in my Google Moon kmz files. Virtual Moon Atlas allows you to program in timed and dates, and has the added advantage of labelling craters so that we can easily compare it with Google Moon. Fourmilab’s Moon Viewer is also useful for looking at both terminator locations, and the Lunar Terminator Visualisation Tool is good for nearside viewsAll of them have their issues, but between them should provide enough to demosntrate the point we are trying to make here.

In order to check whether the programs give a reasonable estimate of the terminator position, I found a random photograph taken from Earth where the time was known to verify them, and also to try and work out which VMA configuration worked best.

The photograph below left was taken by Mark Kilner on 15/07/09 at 02:15 GMT, and I’ve compared it with a couple of VMA settings and the LTVT prediction (inside right) and Fourmilab (right). LTVT’s red and blue lines mark the penumbra and terminator boundaries respectively.

The first thing to point out is the software versions don’t take account of the lunar terrain - they present the terminator as a straight line, whereas in reality the lumps and bumps of craters and mountains make the actual line deviate from a perfect path. Changes in lighting conditions in craters away from the terminator region are also not accounted for. We always need to bear in mind that these are 2D representations of a 3D object.

The second is that the VMA settings on the right, where terminator smoothness has been set at maximum, are probably better at representing reality byt are actually less helpful, as the effect of fading in the lunar night seems to mask the actual location of the terminator and make it difficult to see it precisely.

All of them give an accurate prediction of the terminator’s location, although Fourmilab is perhaps the least useful, but it does at least allow the far side to be shown. Another benefit of choosing a sharper VMA terminator (as opposed to smooth) is that it reduced ‘jagged edges’ - the computation processes in the software can produce a zig-zag terminator line, particularly with smoothness at a maximum and which is obviously not helpful here.

For the purposes of what we are doing here, I have adjusted the settings in VMA so that diffuse and specular lighting at a maximum and the penumbra to low. This is to improve what we are seeing on screen and not to fiddle the results. If anything, it is a hindrance to what I want to demonstrate, as it makes the surface lighter and the terminator a much straighter and more solid line. The default settings are more accurate in terms of what we see in photographs, but it is much more difficult to see surface detail when you zoom in close.As with anything I do concerned with Apollo, all the resources I use are freely available, and you are welcome to try it all for yourself.

Click the links below to see the different sections.

Apollo Index Apollo 08 -10 Terminators
Apollo 11-12  Terminators Apollo 14-15 Terminators Apollo 16-17 Terminators