... all those NASA Photos of the Day with color adjustments to make them more appealing wallpapers - those are all naturalistic.
Great post, interesting discussion, thank you! A quick point--astronomers add color to photos taken with telescopes to reveal stuff that we are unable to detect with our human eyes. Objects in space can glow in a wide range of light, from radio waves to gamma waves, that our human eyes can't detect. The cameras on telescopes, however, use plates that can detect such light, and then astronomers add colors to those images so we can see the objects. These cameras are also more sensitive in ways than human eyes, and they can collect light over time, which the human eye doesn't do. This is done to learn about the universe, to see what we can't see with our naked eye. The great wallpaper for PCs is a secondary benefit. (Of course, there are all sorts of non-scientific images on the internet, and anything goes with those.)
Many of us have seen the great image of the Horsehead Nebula, with all those pink and purple colors. You think, OK, I want to see that with my actual eyes. So you jump in your Asp and fly 1,000 light years toward the nebula and look out through the windshield with your own eyes. What would you see in real life? The blackness of space with bright stars. Some of the stars may appear brighter than they did from Earth, but you won't see the amazing pink clouds of dust and gas. It's there, you just can't see it without the help of a camera.
At any rate, I'm not advocating that the colorful nebulas be removed from ED! No, that would be disappointing. We can pretend that our canopy is showing us light we couldn't otherwise detect with our eyes, or we can just not think too much on it and enjoy this game naturalistically.
btw, an amazing book on the topic of astronomer space pics and how and why they add color is called "Coloring the Universe," which is where I take the Horsehead example from.