How do galaxies look to the naked eye in space?
You can see the one you live in – and many others will look the same. When you look up into the night sky and see the Milky Way, that’s your own galaxy seen edge-on. Well, not quite – what you’re seeing is just the arm of our spiral galaxy our solar system is embedded in. There are no other spiral galaxies within view that you can distinguish from a single point of light – the rest are really that far away! There are globular clusters – another form of galaxy. Seen up close, they’d look just like the night sky you see above you if you consciously ignore the band of light making up the Milky Way – just a bunch of stars scattered randomly across your field of view. If you could get far enough from our sun to get a reasonably close-up view of such a galaxy, it’d just look like a hazy patch of light. As you get closer, that hazy patch of light would appear to grow a bit larger but would also just disappear, to be replaced by that same scene described earlier – a random scattering of stars
Your question is based on a basic misunderstanding. NASA obtains images of distant galaxies both in visible wavelengths and in many other wavelengths (infrared, x-ray, gamma ray, etc). Generally, unless otherwise noted in the captions, the pictures we see of distant galaxies are the optical spectrum (i.e. what the galaxy would look like to the unaided eye if you could actually get close enough to see them that way). However, sometimes the other spectral images are shown (for example, an x-ray image might be shown, with different colors being used to represent different wavelengths or intensities of x-ray radiation). These images are shown to highlight aspects that cannot be seen by the unaided eye. However, such images usually use colors that would not normally be seen in the galaxies (such as vivid greens and blues). One of the most famous pictures of galaxies published by NASA is this one: http://apod.nasa.gov/apod/ap04
