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Old November 21, 2003, 03:38 AM
Arnab Arnab is offline
Cricket Legend
Join Date: June 20, 2002
Posts: 6,069

Umm and your point is?

How does that refute the case that those are not real colors?

Here's another article:

"Ridiculous" is how Kenneth Brecher, a professor of astronomy at Boston University, views the question of the color of the universe. "Meaningless and absurd," he calls the whole affair. "It's very nearly white." But even that view depends on a viewer's point of view.

Brecher complains that "color is not what most astronomers and physicists think it is." It involves hue, saturation and brightness, he instructs, and it can't be thought of as just a wavelength or a frequency.

On a more popular note, Brecher suggests the very vocabulary of astronomy is riddled with misleading color terms. Red giant stars like the bright and popular Betelgeuse, for example, are not really red, though they can sometimes appear so from Earth.

"If you could walk up to Betelgeuse, it would look white," he says.

That's because the star's light would overwhelm the color-sensing cones in your eyes. Only from a great distance, when the star is relatively dim, can the cones sometimes detect a hint of red. The vast majority of red giants, however, set off only the rods in your eyes, which cannot detect color at all. So most stars appear white, regardless of how they are classified.
The quintessential Hubble photograph is a 1995 image of the popular Eagle Nebula, also known as M16 or the Pillars of Creation. The soaring structures had one of their red emissions converted to green -- by the astronomers who took the picture -- in order to highlight scientific detail. In "reality," no green was detected coming from the Pillars.

Interestingly, all Hubble images are created with black-and-white cameras. Ones and zeros are sent to Earth. Color is dropped in later with the popular Photoshop program.

"The color of objects that astronomers release are not really representative of a thing one might imagine exists, which is the objective color of a star or a galaxy," Brecher said in an interview last month during a meeting of the American Astronomical Society in Albuquerque, where he made his case before his peers.

"Color is a very, very subjective phenomenon," he said. "Color is in the eye of the beholder."
Levay and his colleagues sometimes take the editing process another step. Images made with Hubble's infrared camera, called NICMOS, have no intrinsic color values in the visible spectrum. To these photos, the image specialists typically apply a corresponding range of colors from the visible realm in a logical pattern -- red for longer wavelengths and blue for shorter.

"Color is a somewhat fuzzy term," Levay admits in relation to the infrared pictures. "We are artificially applying a perceptual color to light that we cannot perceive." One astronomer would not necessarily apply the same colors to a given infrared image as another, he said, but the same logic with respect to wavelength shifts is typically employed.

Levay points out that what he does is nothing more than an extension of two manipulation techniques that transformed modern astronomy.

"We've been manipulating our view of the universe since the advent of black-and-white photography," he said. "And even before. A telescope manipulates your view of the universe, because it expands the size of your eyes."
This Hubble image of four colliding galaxies, released in earlier this month, was created mostly with infrared light. Astronomers mixed some visible light taken with the telescope's optical imager, too. The visible light was recorded as yellow but made blue before being combined with this picture:

[Edited on 21-11-2003 by Arnab]