Are the colors ‘real’ in astronomical images?
In colored photos of galaxies, stars, planets, and more, what you see is not necessarily what you get
A colored view of the lind 483, one hour-sized system jets and two central protostar out of the middle-formation. Captured by James Web Space Telescope, this image uses false colors to highlight some structural details. The Lynds 483 is very stretched to fit in the viewing area of JWST, and therefore is partially cut into this image.
When I give a public talk about space and show the latest shiny images from Hubble Space Telescope Or James Web Space Telescope (JWST), is one of the most common questions I get, “What are these objects In fact Humshakal? “Does it usually mean: if you were looking at them with your own eyes, will you see this?
The answer is almost not always. But it is not that astronomers are removing photos! This is just that cameras (especially on telescopes) and eyeballs work in very different ways. Any picture in which you take with your smartphone, in which what your eye is visible can repeat completely. Our technology is the best estimated What do you see – and sometimes we never want to do that.
Two types of cells in your retina, called rods and cones, are the basis of human vision. The rods cannot detect color, but are good at registering low levels of light (this is why the unconscious light from most stars looks white without any eye). Cone are cells that begin to understand the color, and they come in three types: each cone is sensitive to red, green or blue light. When we look at an object, we come from a mixture of light detected by the cone to see the colors. This is certainly an unprecedented more complex process that I have just described, but it is gist.
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Some digital cameras may mimic this approach. Instead of light-sensitive biological cells, they have small pixels that essentially count every photon that hits them and stores that number electronically. In this system, a bright object, which emit more light, contains a large number of photons compared to the dimber object.
These pixels are not able to separate the color internal, though. They just see a photon and record it. To get the color information, each pixel can be covered by a filter that only gives through a series of colors in the red, green or blue parts of the spectrum. A color image emerges after counting of raw per-pixel photons-then sorted and expressed by specific colors of light detected light.
It is called a three-color image, and it is close to the eye. Astronomical cameras usually use large red, green and blue filters, instead of viewing Tiny filter A smartphone camera uses for individual pixels, but the end result is very similar. Either in the case, however, the color filter can not usually match your eye color response, so there is no image perfect What you saw Nevertheless, it can be very close.
This is quite good for making a good picture – that is, if we are trying to take an image that matches the eye. We call images like that “true color”, although technically it is a false name because it is actually only a guess.
Such images of cosmic objects are Dear (And loved the public very much) but for limited use for real scientific research. For him, astronomers generally prefer to individually analyze images of any color-filter instead of combining them to create a three-color picture.
This is because “color” is much more than making beautiful pictures. The Sun emits light in a wide range of wavelengths – which we call a constant spectrum – and when we see, say, a flower, it reflects the mixture of those wavelengths of light, which we see as color. Most stars emit a constant spectrum, but do not do all astronomical objects.
Hydrogen in a gas cloud, for example, emit light on a very specific wavelength, although most usually occurs at 656 nanometers (in red part of the spectrum). This way makes emissions called line spectrum. If astronomers want to know where hydrogen is in that nebula, they use the “narrow-band” filter that allows that specific wavelength of light to reach only a detector. These filters can be tuned to separate light from any huge variety atoms and molecules that can be in the gas cloud, Allow to measure the structure, temperature, density, structure and other properties of the cloud,
Most Nebula Photos that you use a combination of these narrow filters, so how these pictures look, any uncontrolled first-person is very different from the scene that you will get if you were physically floating nearby. Imaging process is different, so images Look apart. And that’s fine! Astronomers are not trying to fool you or anyone else. This is just that these objects emit light differently than spectrum, developed to see our eyes, but we still want Look Them. So we make such images to do so.
I never walked on a good name for this process, though. The “false color” was popular for a while, but is out of favor because it means fecary. The “unnatural color” is worse. The technique is worth the crisis of any nomenclature, however, because it allows us to convert different types of light into images. Some camera detectors are sensitive to infrared lights – not only the detector in JWS but also in the new smartphone. Others can lift ultraviolet light, X-ray and other types of nonopical lights.
This allows the construction of images with a mixture of light from electromagnetic spectrum. For example, you can create a picture where ultraviolet light is shown as blue, visible light, as green and infrared as red. Satellite pictures indicate it; Vegetable is an excellent reflector of infrared lightSo it looks bright red in such images, which instead of green to see your eyes. Astronomical images also, often do it with more colors: many hubble images, for example, use five or more filters that are then assigned to different colors each. it The resulting final images especially makes us aliveAlthough they are not, at least as far as your eyes are concerned, in true color.
Finally, the way a picture is made depends on its use. Sometimes astronomers do single filters, many filters or no one, depending on what they are measuring. And the images you see with binoculars – and up – the world can be made in any way, then balanced and delicately processed to enhance your natural beauty.
You can make a case nobody Among them are in true colors. But then, if they Were, They will be unable to reveal the true nature of objects or to reveal the true nature of objects showing different types of invisible light. So in that sense, they are All Truth!
