The James Webb Space Telescope from NASA is renowned for penetrating deep into the cosmos with an unmatched degree of accuracy and sensitivity. However, its visuals are not just scientifically invaluable — they are aesthetically pleasing as well.
From the deep blues and vibrant golds of the stunning Southern Ring Nebula to the vivid pinks, oranges, and purples of the remnant from the Cassiopeia A supernova, images captured by the James Webb Space Telescope (JWST) depict the universe in striking hues. The visuals produced by the orbital observatory are often so extraordinary that one may ponder: Do these cosmic entities truly appear this colorful? And how would these celestial marvels appear if we could observe them with our naked eyes, rather than through a display?
It turns out that scientists are not entirely certain. “The quickest response is, we don’t know,” stated Alyssa Pagan, a scientific visuals developer at the Space Telescope Science Institute (STScI) and part of the team responsible for the vivid colors in JWST images. However, despite this lack of certainty, one thing is clear: Your own eyes would not perceive the universe in this manner.
If you were somehow capable of directly observing these objects with your own vision, you might witness something akin to the images obtained by telescopes that observe the universe in visible light, like the Hubble Space Telescope, Pagan explained.
Nonetheless, that comparison isn’t precisely correct since Hubble is significantly larger and more sensitive than the human eye, thus allowing it to capture considerably more light. Additionally, visual-light telescopes may reveal different characteristics of an object than an infrared telescope would, even when aimed at the same target.
JWST operates as an infrared telescope, meaning it detects the universe in wavelengths of light that are longer than that of red light, which possesses the longest wavelengths perceptible by our vision.
How are colors selected for JWST images?
So how precisely are the colors for JWST’s magnificent images selected?
The telescope’s focus points are initially viewed through various filters affixed to the telescope. Each filter can “detect” specific ranges of infrared light wavelengths. JWST’s Near Infrared Camera, which serves as the primary camera for the telescope, is equipped with six filters, each capturing slightly varied light wavelengths. By combining these visuals into a composite, Pagan and Joe DePasquale, another scientific visual developer at STScI for JWST, can produce the full-color images.
When Pagan and DePasquale first acquire the images, they appear monochromatic. The colors are added subsequently as the data from different filters are translated into the spectrum of visible light, Pagan detailed. The longest wavelengths are represented as red, whereas the shorter wavelengths manifest as blue or purple.
“We are utilizing that relationship between wavelengths and light colors, and we are simply applying it to the infrared,” Pagan noted.
Once each color is incorporated into the image, it may undergo further modifications. At times, the original colors may render an image looking muted or dusty, so adjustments are made to enhance the vibrancy and clarity. The colors may also be altered to highlight certain features that are difficult to differentiate.
Pagan and DePasquale collaborate with researchers to ensure the images remain scientifically accurate, especially if they coincide with specific scientific discoveries, Pagan added. While the colorized images do not deliver explicit scientific information, they can aid in illustrating certain findings.
Occasionally, they can also assist scientists in identifying areas for further research, Pagan explained. For example, the most distant objects in JWST’s first deep-field image — which appear red due to the light traveling such vast distances being stretched — presented opportunities for studies on the early universe when these objects existed as depicted in the deep-field visual.
Are JWST images ‘authentic’?
The colors in JWST’s images may not be “authentic,” but don’t misunderstand — the colors are not intended to deceive, nor are they selected merely to make these objects appear stunning.
Instead, the images are crafted to convey as clearly as possible what JWST is capable of observing — and what our eyes cannot.
You can observe some of the distinctions between visuals from visual-light and infrared telescopes by comparing the images of the renowned Pillars of Creation captured by JWST and Hubble, illustrated below.
While large sections of the pillars seem dark red in the Hubble image, the JWST image represents most of the formation in golden and orange hues. This suggests that the visual light emitted by the pillars has a longer wavelength (red) and is somewhat closer to the center of the infrared light spectrum depicted in the image.
A significant amount of the hazy material enveloping the pillars in the Hubble image, and even some of the structures of the pillars themselves, is also missing from the JWST image, indicating that this portion of gas and dust is transparent in infrared. The JWST image further accentuates more areas of star formation in red, which are concealed by dense clouds of gas and dust in the Hubble image.
By incorporating these colors into the visuals, scientists enhance public appreciation for the James Webb Space Telescope and its contributions to astronomy. “We’re simply trying to amplify aspects to make it more scientifically approachable and also engaging,” Pagan stated.