Thursday, September 16, 2021

Are the colors we give to the Universe real?

 Blue, violet, red or green are colors with which we usually associate or recall graphically the universe.  Perhaps it is because the images that usually present us of stars, planets or galaxies are intervened so that we can better appreciate the composition of the elements in space. The truth is, the most popular association between us when someone asks us about how we imagine the universe is the color black, the sheer absence of color. Why? Perhaps it is an explanation that we give to the criteria of "infinite", "immensity" or "unknown", relating them to a color that psychologically means us this. 

 Actually, the universe has lighter colors than we can imagine, and science checks that out. A study by American scientists and astronomers Karl Glazebrook and Ivan Baldry showed that the color synthesis of all the lights in the universe is beig. They came to this conclusion almost by chance, because their initial objective was to make a spectral analysis of different galaxies investigating the formation of stars. With a census of 200,000 galaxies they measured the cosmic spectrum that represented the sum of all the energy, in the local volume of the universe, emitted at different optical wavelengths of light.

 The study revealed that about 10 billion years ago the universe was slightly blue thanks to the brightness of the stars, but decreased indicating that red giants are much more frequent and that by a smaller reservoir of interstellar gas,  is greater the decline of new stars, a transition that modified the color palette of space. They discovered 'the color of the universe' and although initially due to a flaw in the software system they used to contrast data and turn it into color codes,  they had announced a turquoise color, published a scientific article in which they clarified the mishap and finally called it "Cosmic Latte" or "Cosmic Latte".

 So where do all the colors that we relate to the universe come from? The answer is through astronomical photography, which tries to make visible what is invisible to us, because it works with contrast and luminosity so that the weakest signals are perceptible and interpreted in the RGB range (red, green and blue) that our brain transforms into the colors we know from seeing an image. The "false color" used in astronomical images is the result of photographs taken by powerful black and white telescopes, where light intensity is measured exclusively, but separately through RGB filters. Astronomical photography not only has an aesthetic value, but also yields important information to understand the dynamics of space.

 For example, there are light emissions from several star formation zones that yield data that may be interesting to scientists. As is "Ha" (emission frequency of hydrogen within the red region of the spectrum);  we also talk about ultraviolet light that is in the blue range, emitted by very hot bodies that have high energy explosions; and, from infrared light, emitted by cold objects like stars or dust that fill much of the universe. These frequencies cannot be captured by the human eye, but because they are energy ranges they are close to visible light. In addition, there are also x-rays, gamma rays, microwaves and radio waves that complement the initial vision of those in space and that, when mixed with different images and their filters, generate their representation in more intense and striking colors for us.

 Although the colours shown in the final images are the result of the mixing of various light emissions,  which with the help of filters make our human eye recognize the colours, they are not false images but quite the contrary. Scientists are able to bring us closer to a more striking reality thanks to the shots made with advanced technology light detectors.

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