Are the Colors in Webb Telescope Images ‘Fake’?

On July 12, the first full-color photographs from the Webb Space Telescope confirmed numerous nebulae, galaxies, and a gassy exoplanet as they’d by no means been seen earlier than. But Webb solely collects infrared and near-infrared mild, which the human eye can’t see—so the place are these attractive colours coming from?

Image builders on the Webb staff are tasked with turning the telescope’s infrared picture information into a few of the most vivid views of the cosmos we’ve ever had. They assign varied infrared wavelengths to colours on the seen spectrum, the acquainted reds, blues, yellows, and many others. But whereas the processed photographs from the Webb staff aren’t actually what the telescope noticed, they’re hardly inaccurate.

“Something I’ve been trying to change people’s minds about is to stop getting hung up on the idea of ‘is this what this would look like if I could fly out there in a spaceship and look at it?’” mentioned Joe DePasquale, a senior information picture developer on the Space Telescope Science Institute, in a cellphone name with Gizmodo. “You don’t ask a biologist if you can somehow shrink down to the size of a cell and look at the coronavirus.”

Webb’s first take a look at photographs helped verify its mirrors’ alignment and captured an orange-tinted shot of the Large Magellanic Cloud. Those early snapshots weren’t consultant coloration photographs; one used a monochromatic filter (its picture was grayscale) and the opposite simply translated infrared mild into the red-to-yellow seen coloration bands, so the staff might see sure options of the cloud they imaged. But now, with the telescope up and operating, the pictures that get launched are filled with blazing coloration, like this latest portrait of the Cartwheel Galaxy.

Astronomy is commonly completed exterior the seen spectrum, as a result of lots of the most fascinating objects in area are shining brightly in ultraviolet, x-rays, and even radio waves (which class mild falls into relies on the photon’s wavelength). The Webb Telescope is designed to see infrared mild, whose wavelengths are longer than pink seen mild however shorter than microwaves.

Infrared mild can penetrate thick clouds of fuel and mud in area, permitting researchers to see beforehand hidden secrets and techniques of the universe. Especially intriguing to scientists is that mild from the early universe has been stretched because the universe has expanded, that means what was as soon as ultraviolet or seen mild could now be infrared (what’s referred to as “redshifted” mild).

“These are instruments that we’ve designed to extend the power of our vision, to go beyond what our eyes are capable of doing to see light that our eyes are not sensitive to, and to resolve objects that we can probably see with just our eyes,” DePasquale mentioned. “I’m trying to bring out the most detail and the most richness of color and complexity that’s inherent in the data without actually changing anything.”

Webb’s uncooked photographs are so laden with information that they have to be scaled down earlier than they are often translated into seen mild. The photographs additionally have to be cleaned of artifacts like cosmic rays and reflections from shiny stars that hit the telescope’s detectors. If you take a look at a Webb picture earlier than processing work is finished, it’ll appear to be a black rectangle peppered with some white dots.

“I think there’s some connotations that go along with ‘colorizing’ or ‘false color’ that imply there’s some process going on where we’re arbitrarily choosing colors to create a color image,” DePasquale mentioned. “Representative color is the most preferred term for the kind of work that we do, because I think it encompasses the work that we do of translating light to create a true color image, but in a wavelength range that our eyes are not sensitive to.”

Longer infrared waves are assigned redder colours, and the shortest infrared wavelengths are assigned bluer colours. (Blue and violet mild has the shortest wavelengths inside the seen spectrum, whereas pink has the longest.) The course of known as chromatic ordering, and the spectrum is break up into as many colours because the staff must seize the total spectrum of sunshine depicted within the picture.

“We have filters on the instruments that collect certain wavelengths of light, which we then apply a color that is most closely what we think it will be on the [visible] spectrum,” mentioned Alyssa Pagan, a science visuals developer on the Space Telescope Science Institute, in a cellphone name with Gizmodo.

The chromatic ordering relies upon too on what parts are being imaged. When working with narrow-band wavelengths in optical mild—oxygen, ionized hydrogen, and sulfur, Pagan suggests—the latter two each emit in pink. So the hydrogen may get shifted to inexperienced seen mild, as a way to give the viewer extra info.

“It’s a balance between the art and the science, because you want to showcase science and the features, and sometimes those two things don’t necessarily work together,” Pagan added.

Webb’s first consultant coloration photographs had been launched July 12, over six months after the telescope launched from an ESA spaceport in French Guiana. From there, Webb traveled about one million miles to L2, some extent in area the place gravitational results enable spacecraft to remain in place with out burning a lot gas.

The telescope unfolded itself on the best way to L2, so as soon as it was there, mission scientists might get began on aligning the $10 billion observatory’s mirrors and commissioning its devices. The telescope has 4 devices: a near-infrared digital camera (NIRCam), a near-infrared spectrograph, a mid-infrared instrument (MIRI), and a high-quality steering sensor and slitless spectrograph for pointing at targets exactly and characterizing exoplanet atmospheres.

The voluminous quantities of mud in some galaxies and nebulae are clear to NIRCam, permitting it to seize shiny stars at shorter wavelengths. MIRI, then again, can observe discs of fabric that can give solution to planets in addition to mud warmed by starlight.

When telescope photographs are being assembled, picture processors work with instrument scientists to resolve which options of a given object needs to be highlighted within the picture: its piping sizzling fuel, maybe, or a cool dusty tail.

When Webb imaged Stephan’s Quintet, a visible grouping of 5 galaxies, the completed product was a 150-million-pixel picture made up of 1,000 photographs taken by each MIRI and NIRCam. When simply seen by MIRI, although, sizzling mud dominates the picture. In the background of the MIRI photographs, distant galaxies glow in numerous colours; DePasquale mentioned the staff calls them “skittles.”

DePasquale and Pagan helped create the Webb photographs as we’d finally see them, wealthy in coloration and cosmic that means. In the case of the sweeping shot of the Carina Nebula’s cosmic cliffs, completely different filters captured the ionized blue fuel and pink mud. In preliminary passes on the nebula picture, the fuel obscured the mud’s construction, scientists requested the picture processing staff to “tone down the gas” a bit, Pagan mentioned.

Collecting mild in Webb’s hexagonal mirrors is just half the battle relating to seeing the distant universe. Translating what’s there’s one other beast totally.