Are the Colors in Astronomical Images 'Real'?
scientificamerican.com
scientificamerican.com
Yet if some aliens insisted that our planet was a very boring featureless nitrogen-colored ball, we would probably object that their viewing strategy is naive and incorrect.
We are born seeing the universe based on pragmatic decisions about signal versus noise. Our evolved tuning utterly fails in new places, so we should pick new tunings.
And I'd argue that it's all signal. Noise is something very human -- maybe even for carbon-based lifeforms, but I'd be careful to make such broad assertion --, that which is unnecessary or harmful for the needs of the body.
Although space may appear subdued to our eyes, that doesn’t mean it isn’t beautiful—only that we need to borrow better eyes to truly see it
Those multicoloured nebulae are not real objects, they exist only in fantastic pictures overlaid with Neil deGrasse Tyson’s face and some vague sentiments about how wonderful the universe is when it’s very far away from human life. The images are digitally stitched together, the colours are fake, the shapes are not anything that could actually be seen out the window of your spaceship, a real-life nebula is about as exciting as a damp fog.
Color temperatures in the range of 5000 K to 7000 K, where the "yellow" stars belong, are all seen as pretty pure white, with the range of 5500 K to 6000 K, like the Sun, as the whitest. Even a colder star at 4000 K is only very slightly yellowish. Going to lower temperatures, e.g. 3000 K or less, the color becomes definitely yellow, then orange, then red.
You can verify this by looking at lamps with specified color temperatures, to see what color they seem to have for you.
The Sun seen from the Earth is seen as yellowish at noon and as reddish at sunset and at dawn because of the low-pass filter effect of the atmosphere, which removes the blue light from the direct light of the Sun and spreads it over the sky. When the blue sky light and the direct yellowish Sun light are mixed again, like in clouds, you see white light, thus the clouds are white, which is the real color of the Sun. On the Moon, without atmosphere, the Sun would be white.
Going towards higher temperatures, the white stars become blue-green, then blue. There are no green-emitting black bodies.
Though, you could say it's indirectly designed for beauty. When astronomers process an image, they are looking for interesting features to study. And once you've narrowed in on the most scientifically interesting way to process an image, the sorts of striking color contrasts that creates are inherently beautiful because they are unveiling the interesting parts & letting us see the unseen for the first time. And there is selection bias on what is interesting to look at. A violent explosion is both more aesthetically inspiring and teaches us more about how matter works than a picture of a random stairwell, and astronomers love their violent explosions.
That being said, the complaint that the images are "unrealistic" are off-base. The images accurately portray the information that was captured by the telescope. Your eyes often can't even see the wavelengths imaged by space telescopes (like the James Webb Space Telescope), so how you map those wavelengths to RGB is largely arbitrary. As long as you map them in the same order (shorter wavelengths appear bluer, longer wavelengths appear redder), I would consider the images accurate.
It is true that they also look at a lot of grayscale images, though. Differentiating chemicals in nebulas or on the surface of planets isn't always necessary, and you can always take the simpler (but sometimes less useful, since it doesn't make full use of the human visual system) route of looking at multiple grayscale images. A lot of the areas where false color is most useful are well-trodded ground, so we don't necessarily need more images of the same objects when the existing body of research is already rich. And sometimes, a researcher includes an image in their paper just because they thought it looked cool, not because it was useful for the methodology.
There are some rare cases in which an audible might look at a color image, but the overwhelming majority of images astronomers deal with daily are grayscale.
A screenshot of this page would capture a title bar in orange.
The REAL title bar is displayed as dots of green, blue, and red; no orange is present.
Would you rather thaw NASA show you a blank image and say, "This is our newest infrared image from the James Webb Space Telescope!"
They map the images into wavelengths you can see. There's nothing else the can do, other than not showing you the images at all.
There are edge cases in which astronomers will load up images at multiple wavelengths and overlay them, but this is not the normal case. By and large, they're looking at a single channel at a time. Even more commonly than that, they're working with catalogs automatically generated from images.
"How much" isn't a question that makes sense, unless you are looking at a specific set of images. Astronomical images can be generated in many, many ways from all sorts of processes. Sometimes there is natural color included, but enhanced; sometimes a wider spectrum is mapped into visible colors so humans can appreciate it; sometimes, the colors are codes for different features, and there is a key provided, so that the colors can be interpreted to what they mean, rather than corresponding to visible light.
It's not just astronomical images, but all disciplines of science use color keys to depict things that are not colors. Look at a topographical map, and it may have green and brown areas that are simply abstracts. A political map uses 5-6 colors to highlight the shapes states or nations, but these are not "real" colors either. But usually, you're provided a color key, for interpretation.
I think that's getting the priorities wrong. The people who think those images are "fake" and fraudulent don't think that because of that term, they just see the term as a reaffirmation of their preexisting conspiracy theories. Flat earthers will literally deny the evidence of their own experiments when they don't align with what they profess to believe.