Could be generated by the outer lens glass surface or front of lens (uv) filter. I've seen similar ghosting in photographing theatre stage, where there is a strong light source in contrast with a relatively dark background. In theatre, changing the angle of camera to stage can move or eliminate the ghost.
Way to test. Try some moon in dark sky photos where you change the relative location of moon in your frame - off center.
Re color, the appearance of moon being white is likely blown highlights (overexposure) where all channels are driven to 255. A lesser exposure might reveal uneven color channel levels in the moon, as you can see in the cloud (2004 photo).
Remove the UV filter from the front of your lens camera. The green ghost is the reflection of the moon off the relatively green sensor (twice as many green photosites as red or blue) that goes back up to the UV filter glass, then back down to the sensor. The surfaces of your camera lenses are curved so don’t usually generate such recognizable reflections but the flat surface of your UV filter does. The UV glass only reflects a small fraction of the light, but when the light-source is very overexposed this reflection is bright enough to see. If you use M-mode and dial back the exposure enough to to see surface detail on the moon the ghost might be dim enough to not be noticeable but it’s usually better to remove the UV filter, anyway, unless you have a good reason to use it and understand about not overexposing light sources when it’s on.
Robert Shomler and ssprengel,
Your suggestions about the UV filter (which I did indeed have attached to both lenses - well guessed!) make much more sense than my camera shake theory. Thank you.
I'll try out this UV filter theory as soon as a suitably fullish Moon is again visible in my night sky.
I'll also try out your off-centre theory, Robert. Re the colour changes and blown highlights, I'll be more careful with the exposure in the next experiment. Interestingly, the colour changes are in each case (between photographs) different - green in 2004 and blue in 2012. But admittedly I was using different cameras and lenses and possibly even different White Balances.
To this forum's Adobe Moderator:
Thank you for leaving this thread in place.