I think that the goal of the images should be put into consideration. Isn't it better conduct to categorize "satellite photos" as opposed to "images from Google Earth"? This would allow people to put free images in the category as well. I don't really see the use of categorizing images from Google Earth, because they aren't any more or less useful than equivalents from other sources.
A "satellite photos" (or "satellite and aerial photos") category would seem sensible to me.