What's the green colouration on my photo?

[matt_baker]

A couple of months ago I got 100 images of the moon, stacked them and brought out the saturation to reveal the colours. I think that the brown is iron deposits and the blue is titanium but I have no idea what the green is. Is that just how it is when the terminator shows like that?

[symmetal]

The black colour balance was slightly off during capture (quite normal) so your unprocessed image would have had a slight green cast in the blacks. Before doing heavy stretching (levels or saturation) you need to ensure the black and white points of your image are actually colour neutral, if possible. Your background is clipped to zero so the background cast is clipped off and is only visible in the dark areas above level zero. It's best to ensure that the offset or brightness in your image when capturing is set such that the background is not clipped. You can then easily see any colour cast present and neutralise it before stretching. If you wish you can set the background to zero when you've finished processing.

Alan