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Career Officer
Join Date: Jun 2012
Posts: 867
# 9
04-24-2013, 12:39 AM
Astronomers do not use color cameras. For the most part, astronomers and astrophysicists have little use for color images.

If you see a color image of an astronomical object, it was taken using two or more exposures in two or more filters (astronomers almost always use filters that only allow in a certain range of frequencies).

To get a color photograph, you have to choose which filters to use and how to blend them together. Add to that the fact that what we see from Earth is not necessarily what we would see if we were near the stellar object. The interstellar medium leads to what is called reddening and specific types of gasses or dusts between us and the object might further alter which frequencies get through. The worst thing is the atmosphere, which eliminates big chucks of the EM spectrum and lots of wavelengths of light.

What we see in photographs is probably very different than what we would see if we were actually near the object, staring out the window. Things that are in beautiful, bright hues in color composites look like grey or muted colors through a telescope.

Take the U filter, one of the four most commonly used astronomical filters. Most of this wavelength is invisible to the human eye, yet it is often included as visible spectra in Hubble color composite photographs.

Take a look at the Orion nebula with a telescope. It is one of the most colorful objects in the sky, but what you see through the eyepiece is very muted compared to what you see in Hubble CCD images that have been compiled into a color picture.

Last edited by logicalspock; 04-24-2013 at 12:42 AM.