Mouthwash wrote:Source of the post 1. It seems like nebulae are going to be totally false color in the next version, which is disappointing. Correct me if I'm wrong, but those pictures don't give me an impression of realism.
Watsisname wrote:Mouthwash wrote:Source of the post 1. It seems like nebulae are going to be totally false color in the next version, which is disappointing. Correct me if I'm wrong, but those pictures don't give me an impression of realism.
False color images of nebulae are pervasive, but false color does not necessarily mean wrong color. Sometimes astrophotos are taken through specific wavelength filters and then those images are mapped to totally different colors, or they may map non-visible wavelengths to visible colors, which of course will look very unlike how the real thing looks to the eye or even a long exposure with a typical color camera. But other times the images may be mapped to the same color that the filter transmits, in which case the result is pretty close to true color.
To get an idea of the true colors of a nebulae, a helpful tool is to spread its image out into a spectrum, as in a "slitless spectrograph". Here's an example for the Cat's Eye Nebula (top) and Ring Nebula (bottom).
The primary colors are red and a greenish turquoise. Red is from the hydrogen-alpha line, while the turquoise comes from Hydrogen-beta and Oxygen-III. Which matches up pretty well with the following astrophotographs:
So the true color of nebulae actually is pretty close to what the SE snapshots show.
Mouthwash wrote:2) The majority of a galaxy's luminosity in visible wavelengths is from stars. Dust dims and reddens the visible light that passes through it and re-emits in infrared. Clouds of neutral gas are non-luminous (they glow in radio instead). So the only real visibly luminous feature of galaxies besides stars is ionized gas, which glows with the characteristic redish-pink of hydrogen, and is the main feature of star formation regions.