A black-and-white image of the nebula is contrasted with a full-color image that is the result of scientists' processing work.

At left is a monochrome image showing infrared data from the Southern Ring Nebula’s web. On the right is a processed image showing the same view in full color.
image: Gizmodo/NASA, ESA, CSA, STScI

July 12th, first full color image Pictures from the Webb Space Telescope showed a myriad of never-before-seen nebulae, galaxies, and gaseous exoplanets. However, the web only collects infrared and near-infrared light, invisible to the human eye.

Image developers on the Webb team are tasked with transforming the telescope’s thermal image data into the sharpest view of the universe ever seen. They assign different infrared wavelengths to familiar colors in the visible spectrum such as red, blue and yellow. literally What the telescope sees is rarely inaccurate.

“What I’ve been trying to change people’s minds is to stop thinking, ‘Is this what it would look like if I were to fly in a spaceship?'” said Joe DePasquale. rice field. On the phone with Gizmodo, senior data image developer at the Space Telescope Science Institute. “I don’t ask biologists if they can somehow shrink down to the size of a cell to observe the coronavirus.”

webs first test image Check the mirror alignment and Orange shot of the Large Magellanic CloudThese early snapshots were not representative color images. One used a monochromatic filter (the image is grayscale) and the other just converted the infrared light into the visible color band from red to yellow, so the team could see certain features of the clouds they imaged. I made it.But now that the telescope is up and running, the images it releases are full of fiery colors, like this recent one. Cartwheel galaxy portrait.

Astronomy often takes place outside the visible spectrum. This is because many of the most interesting objects in the universe glow brightly in ultraviolet, X-ray, and even radio waves (what category light falls into depends on the wavelength of the photon). Webb telescopes are designed to see infrared light, which has wavelengths longer than visible red light and shorter than microwaves.

Infrared light can penetrate the thick clouds of gas and dust in space, allowing researchers to see previously hidden secrets of the universe. Of particular interest to scientists is that light from the early universe was stretched as the universe expanded. This means that what was once ultraviolet or visible light may now be infrared (known as “redshifted” light).

Graph showing that infrared waves are slightly longer than visible light waves and redder than most visible light.

“These extend the power of our vision, going beyond what our eyes can do to see light that our eyes can’t perceive, and objects we can possibly see on our own.” It’s a device designed to solve the eye,” said DePasquale. “I’m trying to bring out the deepest, richest color and complexity inherent in the data without actually changing anything.”

Raw images of the web contain so much data that they must be scaled down before being converted to visible light. We also need to remove artifacts from the image, such as cosmic rays hitting the telescope’s detectors and reflections from bright stars. If you look at the Webb image before the processing work is done, it looks like a black square with some white dots scattered around it.

A raw image of the Carina Nebula as seen by NIRCam is almost black to the human eye, with white flecks from some light sources. It is clear that infrared light is invisible to the human eye.

A raw image of the Carina Nebula as seen with NIRCam before the infrared light was converted to visible wavelengths.
image: Space Telescope Science Institute

The Carina Nebula's Cosmic Cliffs are a vibrant rust color against the deep blue of ionized gas and deep space.

“I think there are some connotations attached to ‘colorization’ or ‘false color’ that mean that the process of arbitrarily choosing colors to create a color image is underway,” says DePasquale. said. “Typical color is the most preferred term for the kind of work we do. I think it involves converting light to create a true-color image, but our eyes are not so sensitive. It is within the wavelength range that is not

Longer infrared wavelengths are assigned a red color, and shorter infrared wavelengths are assigned a blue color. (Blue and violet light have the shortest wavelengths in the visible spectrum, and red has the longest.) This process is called color order, and the spectrum is the It is split into as many colors as needed to capture the full spectrum. image.

“The device has a filter that collects light of a certain wavelength and applies the color it thinks is closest to it. [visible] Alyssa Pagan, science visual developer at Space Telescope Science Institute, said in a call with Gizmodo:

The order of colors also depends on which element is being imaged. Pagan suggests that when dealing with narrow-band wavelength light such as oxygen, ionized hydrogen, and sulfur, the latter two both emit in the red. As such, hydrogen may shift to green visible light in order to provide more information to the viewer.

“The balance between art and science is important because we want to showcase science and function, and sometimes those two things don’t always work together,” added Pagan.

Webb’s first representative color image was released on July 12, more than six months after the telescope launched from the ESA spaceport in French Guiana. From there, Webb traveled about a million miles to his L2. L2 is where the effects of gravity allow the spacecraft to stay in place without consuming too much fuel.

The telescope deployed en route to L2, so once there, mission scientists could begin aligning the $10 billion observatory’s mirrors and commissioning its instruments. The telescope has four cameras: a near-infrared camera (NIRCam), a near-infrared spectrograph, a mid-infrared instrument (MIRI), a precision inductive sensor and a slitless spectrograph for precisely targeting and characterizing exoplanetary atmospheres. I have equipment.

The vast amounts of dust in some galaxies and nebulae are transparent to NIRCam, allowing bright stars to be seen at shorter wavelengths. MIRI, on the other hand, can see disks of material displaced by planets and dust warmed by starlight.

Once the telescope’s image is assembled, the image processor works with the instrument’s scientists to determine which features of a particular object should be emphasized in the image. Perhaps its hot gas, or cold dust tails.

A pentad of galaxies seen with three mid-infrared filters. In the mid-infrared, the focused galaxy is dominated by violet hues, while the background galaxy is a cluster of reds, yellows, and blues.

When Webb imaged Stephan’s Quintet, a visual grouping of five galaxies, the finished product was a 150-megapixel image composed of 1,000 images taken with both MIRI and NIRCam. did. But as seen by MIRI, hot dust dominates the image. Distant galaxies shine in different colors in the background of MIRI images. According to DePasquale, the team calls them “Skittles”.

DePasquale and Pagan helped create the Webb images we finally see, rich in color and cosmic meaning. In the case of the cosmic cliff-clearing shot of the Carina Nebula, various filters captured the ionized blue gas and red dust. In the first pass of the nebula image, the gas obscured the dust structure, so the scientist asked the image processing team to “tone down the gas a bit,” Pagan said.

Collecting light with Webb’s hexagonal mirror is only half the battle when it comes to seeing the distant universe.


By Author

Leave a Reply

Your email address will not be published.