Since I started this site I notice more and more that people do not know too much how to interpret colors in the photos of celestial objects any and I think it’s significant enough to talk about, so, let’s talk about.

You should know that the breathtaking photographs taken by space telescopes such as Hubble or Spitzer are taken in grayscale (that is, with different shades of grey) and filters are used over according to the wavelength of the light have want treated. These photographs taken with different filters are then very often assembled into what have it call a composite image, that is to say a single photograph constructed from multiple images of the same object with a different light wavelength. It is also possible to display the infrared or ultraviolet.

These filters can also highlight gases that are not visible to the naked eye (hydrogen, nitrogen or helium, for example) or of very fine dust clouds.

Another technique is to exaggerate certain colors normally not perceptible to highlight a geological difference of soil for example.

Here are a series of comparisons that should tell you a bit more:

lunecover1

Behold the moon as we are used to see.

serveimage

And here’s the Moon colorized with a high exaggeration of color. (credit: Baudouin Martineau)


heic0910e

Carina Nebula

heic0910f

Infrared Carina Nebula


The NASA/ESA Hubble Space Telescope has captured a new image of the galaxy NGC 1132 which is, most likely, a cosmic fossil - the aftermath of an enormous multi-galactic stack-up, where the carnage of collision after collision has built up a brilliant but fuzzy giant elliptical galaxy far outshining typical galaxies. NGC 1132, together with the small dwarf galaxies surrounding it, are dubbed a "fossil group" as they are most likely the remains of a group of galaxies that merged together in the recent past. In this Hubble image, NGC 1132 is seen surrounded by thousands of ancient globular clusters, swarming around the galaxy like bees around a hive. These globular clusters are likely to be the survivors of the disruption of their cannibalised parent galaxies that have been eaten by NGC 1132 and may reveal its merger history. In the background, there is a stunning tapestry of numerous galaxies that are much further away.

Galaxy NGC 1132, constellation of Eridanus.

This image of the elliptical galaxy NGC 1132 combined an image from NASA's Chandra X - Ray Observatory obtained in 2004 with images from the NASA/ESA Hubble Space Telescope made in 2005 and 2006 in green and near-infrared light. The blue/purple in the image is the x-ray glow from hot, diffuse gas. The giant foreground galaxy, numerous dwarf galaxies in its neighbourhood, and many much more remote galaxies in the background are seen in visible light.

Galaxy NGC 1132 with X-ray

For further / sources:

http://www.slate.fr/story/10331/pourquoi-les-photographies-de-lespace-sont-SI-jolies

http://www.franceculture.fr/Sciences/Espace-dans-loeil-du-telescope#

http://documents.irevues.INIST.fr/Bitstream/handle/2042/2430/09 •Petremand .pdf

http://www.Futura-Sciences.com/magazines/Espace/infos/ACTU/d/Astronomie-astrophotographie-Lune-Couleurs-34908/

https://www.spacetelescope.org/images/heic0910e/

https://www.spacetelescope.org/images/heic0910f/

https://www.spacetelescope.org/news/heic0804/

http://spacetelescope.org/images/opo9914d/

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Categories: Blog, Explanations, Photographs

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