Oh, and the green fuzz in the SDSS image, isn't that usually red?
I saw a lot of these SDSS-images yesterday, all showing green, where the are normally coloured red..
It took me a moment to get used to that, but Joseph's comment was right: nothing is absolute, and it is all a matter of perspective. There is no such thing as "looking at a galaxy, as it really is". 'Many objects in them can't be seen. And in visual light can't see diffences in temperature too well. And there is much more radiation then only visible light. So what exactly is 'reality' here?
To get results, that show as much details as possible, several photo's are taken of an object in different spectral ranges, and then joined together again, often manipulated to get better contrast, etcetera.. Computer colours are used to point at differences and qualities: indeed, you are visually fooled, but you get details back. It is a matter of what you think is most important?
For instance, I saw a picture of the California Nebula, that seemed to be photoshopped to show as much of the structure as possible. OK, you get fooled a bit, because you would never see this at a short distance from the nebula. But what is interesting about an H-cloud anyway? The structure is more important..
If we were only 1000 lightyears away from a galaxy, we would get a complete different picture anyway. So I got used to the idea, we don't see much anyway, and any way of presenting an object has it's own features, or aspects of reality.. However, I do keep feeling suspicion and objection to making too much art out of galaxies.
Still haven't found out, why SDSS uses green..
But to give you an idea about reality and manipulation. Someone gave me a picture of his grand-grandfather once, 100 years old. I scanned it, and started photoshopping it, mainly tuning light and contrast, but also using noise reduction, and cutting out some spectra..
Suddenly it showed, the man had actually a beard. And he really did have ears. And the expression on his face became more clear. So it was a great result.
But that's where the problems began. In some settings his lips were thicker, or had a different shape, changing the whole expression on his face. And was it really his cheeks, I was accentuating, or was it distortion, that had nothing to do with that?..
So after a lot of hesitation, in the end I just produced 4 different versions of the restoration, telling my friend: figure out yourself, what the man in reality really would have looked like?
My guess is, it's the same with galaxies.. 'Manipulation' is mainly good, but always will produce some new illusions..
