Far and Away with the James Webb Telescope

Members of the Johns Hopkins community respond to seeing the first images from the James Webb Telescope.

Issue: Fall 2022

Last July 12, people around the world witnessed a first-ever in science: the release of initial images from the James Webb Space Telescope (JWST). A veritable smorgasbord of stunning cosmic visuals, the data from the telescope will enable scientists to learn and see more about the universe than ever before. Following are some of the early images as well as comments from members of the Johns Hopkins community. 

Early Images from the James Webb Telescope

An image of five galaxies known as Stephan's Quintet. Two of the galaxies appear close together at the center of the image. One appears directly above, and another slightly to our left near the bottom of the image. Each of these four galaxies presents as an irregular dot of brilliant white light surrounded by glowing haze. A fifth galaxy hides at our center left in an oval shape marbled with a tangle of golden orange lines. Similar golden orange tangles appear around the two galaxies at the center of the image, and the galaxy above them. Above the two galaxies at the center is a bright, light blue cloud. This is a shock wave uncovered by the Chandra data. Scattered across the image are specks of white and golden orange light, gleaming stars and distant galaxies. Credits: NASA, ESA, CSA, STScI
Data from James Webb Space Telescope’s Near-Infrared Camera (NIRCam) were used to make this extremely detailed image of the Southern Ring Nebula. This is not only a crisp image of a planetary nebula—it also shows us objects in the vast distances of space behind it. The transparent red sections of the planetary nebula—and all the areas outside it—are filled with distant galaxies.
Credits: NASA, ESA, CSA, STScI
Fluffy tan-colored nebula clouds, with rust-colored highlights, surround a black central area. Within that area, the focal point of the image is one large yellow star with eight long thin points. To the right of this star is a bright star cluster in an oval shape. The stars within the cluster look like tiny pale blue sparkles. The cluster is more densely packed at its core and scatters outward. Towards the bottom of the image, multiple arms appear to spiral out of a cloudy tan knob. Taken together, the structures resemble a spider or a squid. Other blue and yellow eight-pointed stars, as well as distant galaxies, are dotted throughout the image. Credits: NASA, ESA, CSA, STScI, Webb ERO Production Team
In this mosaic image stretching 340 light-years across, Webb’s Near-Infrared Camera (NIRCam) displays the Tarantula Nebula star-forming region in a new light, including tens of thousands of never-before-seen young stars that were previously shrouded in cosmic dust. The most active region appears to sparkle with massive young stars, appearing pale blue.
Credits: NASA, ESA, CSA, STScI, Webb ERO Production Team
This image – the first released from NASA’s James Webb Space Telescope – shows the galaxy cluster SMACS 0723. Some of the galaxies appear smeared or stretched due to a phenomenon called gravitational lensing. This effect can help scientists map the presence of dark matter in the universe. Credit: NASA, ESA, CSA, STScI
Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Thousands of galaxies—including the faintest objects ever observed in the infrared—have appeared in Webb’s view for the first time.
Credits: NASA, ESA, CSA, STScI, NIRCam
Image of galaxy IC 5332 as taken by the Webb telescope’s MIRI instrument, resembling gray cobwebs in the shape of a spiral. These “cobwebs” are patterns of gas spread throughout the galaxy. The core of the galaxy glows a dark blue. Stars, seen as tiny blue dots, are scattered throughout the image. There are also sparser, larger red dots spread out among the spiral arms. The background of the image is dark. Credits: ESA/Webb, NASA & CSA, J. Lee and the PHANGS-JWST and PHANGS-HST Teams I
Image of galaxy IC 5332 as taken by the Webb telescope’s MIRI instrument, resembling gray cobwebs in the shape of a spiral. These “cobwebs” are patterns of gas spread throughout the galaxy.
Credits: ESA/Webb, NASA & CSA, J. Lee and the PHANGS-JWST and PHANGS-HST Teams
Neptune's rings are clearly visible in this Webb image. Against a dark background, the planet resembles a pearl with ethereal concentric ovals around it. Credits: NASA, ESA, CSA, STSc
In September, Webb delivered the clearest look at Neptune’s rings in 30-plus years and, for the first time, in infrared light.
Credits: NASA, ESA, CSA, STScI
An image of five galaxies known as Stephan's Quintet. Two of the galaxies appear close together at the center of the image. One appears directly above, and another slightly to our left near the bottom of the image. Each of these four galaxies presents as an irregular dot of brilliant white light surrounded by glowing haze. A fifth galaxy hides at our center left in an oval shape marbled with a tangle of golden orange lines. Similar golden orange tangles appear around the two galaxies at the center of the image, and the galaxy above them. Above the two galaxies at the center is a bright, light blue cloud. This is a shock wave uncovered by the Chandra data. Scattered across the image are specks of white and golden orange light, gleaming stars and distant galaxies. Credits: NASA, ESA, CSA, STScI
An enormous mosaic of Stephan’s Quintet is the largest image to date from Webb, covering about one-fifth of the moon’s diameter. It contains over 150 million pixels and is constructed from almost 1,000 separate image files.
Credits: NASA, ESA, CSA, STScI

How JHU Sees the James Webb Images

A worthwhile endeavor 

Barbara Mikulski

Outside the Space Telescope Science Institute on July 12, Senator Barbara Mikulski, Homewood Professor in the Department of Political Science, gave a toast with a crowd of scientists holding champagne flutes. “This is a 30-year, $30 billion overnight success,” she joked. “But it’s also a job worth doing and a job well done. I’m so proud of you, and your country is proud of you.” Mikulski, who served as U.S. senator from Maryland from 1987 to 2017, has always been a powerful champion for NASA and an influential figure in space policy. Believing that a strong U.S. space exploration effort was imperative, she advocated staunchly for the Space Telescope Science Institute (STScI) and Goddard Space Flight Center, and for full funding for missions including the Hubble and Webb telescopes. 

Only the beginning 

There were times when we weren’t sure if things would work, but they’re working spectacularly. It’s just amazing. It’s blowing my mind. We get these amazingly detailed images of distant galaxies and all these tiny little clumps and star clusters that just pop out that we could never see before. And so, we’re really seeing for the first time what galaxies looked like in the early universe. Every observation that Webb makes for the first year has the potential to transform our understanding of the universe. For many years to come, we’re going to be doing so many exciting things. We’re going to answer so many questions, and then, of course, we’re going to have more questions that we never dreamed of.” 

—Dan Coe, A&S ’04 (MA), ’07 (PhD),
Astronomer, instrument scientist, 
Space Telescope Science Institute/JWST 

A remarkable achievement

Just the fact that this mission was decades in preparation and having a textbook-perfect launch. Just being involved in seeing all these different subsystems that need to work together—having 18 different individual mirror segments working as one—for all the instruments getting initial data and starting to process it and getting things working to the point where we could take these amazing images. It was a lot of work, people giving it their all for months on end. From a scientific perspective, there is something about humanity that just really wants to know about where we are and where we came from. And what we’re going to learn from JWST is definitely going to feed into that and give us probably more questions—it always does—but also give us some answers that I think will only increase our awe and appreciation of the universe.” 

—Stephanie LaMassa, A&S ’08 (MA), ’11 (PhD),
Scientist, branch manager,
Space Telescope Science Institute/JWST

Reality check

I just kept looking at it and thinking, like, ‘Is this real? How could this be real?’ And, really, at some level, I think the thing that struck me the most was, I grew up, like many of us, thinking of the sky as a place that was dark at night with a few exceptions of stars and little blobs of light. And when you can see this deeply, and with this kind of resolution, actually you start to see most of the image is actually light. The darkness starts to become the rarity, if you know what I mean. And so it’s almost like a completely different conception of the universe as a place that’s mostly filled with activity, mostly filled with luminous things, mostly not empty.” 

—Adam Riess,
Bloomberg Distinguished Professor,
Thomas J. Barber Professor of Physics and Astronomy,
Nobel Laureate

More Than Meets The Eye

Joseph Depasquale

Those Webb images that we’ve come to accept as definitive depictions of space didn’t get here by scientists simply snapping a camera shutter. Instead, they’re the result of meticulous work by the Space Telescope Science Institute’s science visuals developers Joseph DePasquale and Alyssa Pagan. 

DePasquale and Pagan were on the STScI team that decided what Webb’s early targets would be, so they had some idea of what they would observe that first day. But the moment the first image began to emerge from their black screens was no less stunning. 

“As I was uncovering the beauty of these images, I reflected on all it took to get here, and felt so proud of humanity for designing such scientific marvel that seemed impossible to achieve, but forever would change our understanding of the universe,” says Pagan. “Being one of the first people to explore these images was so mind-blowing, and I feel a great responsibility to present the data in a way that showcases the beauty of our universe while also being true to the science in a way that is most accessible and as clear as possible.” 

Alyssa Pagan

The team is sometimes asked whether the images are “real.” The answer is a resounding yes, they say. If we could fly into space and stand beside a nebula or exoplanet, what we would see would not be identical to the images. But that’s not because they’re not there; it’s because our eyes can’t perceive them. What the team does is translate the physics of the objects into light visible to us. 

“It’s all real stuff out there, and it’s just that we’ve built instruments that are really sensitive to it, to be able to see something that our eyes are not sensitive to,” says DePasquale, senior science visuals developer. 

Making the Data Visible

The process of transforming data into images perceptible to the human eye is extraordinarily complex, requiring both art and science. Here, DePasquale and Pagan share some of the highlights. 

First View

The images arrive embedded in a huge file of metadata. When DePasquale and Pagan open an image for the first time, it appears black, because while Webb’s detectors are excellent at sensing intensity of light, they do not pick up on color. 
Filters that “See”

But the telescope is outfitted with filters, and that is how the team eventually reveals the colors hidden in the initial image. The filters are there to allow scientists to look at very specific wavelengths of light. They help them determine, for example, which galaxies in a field of view are very distant or very dusty, because those only show up in the longest wavelength filters, appearing red.
 
“Astrophysically, the color actually has meaning to it. It’s not just about making a pretty picture,” DePasquale says. 
“Stretching” the Image Data

Much of what interests scientists out in space has infrared light, which is not visible. So creating an image perceptible to our eyes requires working with those filters to translate the data into visible form. In a process DePasquale describes in the team’s blog, they “stretch” the data, digging down to the details using a mathematical function to increase the brightness of the darkest pixels while maintaining details within brighter pixels. Using a histogram—you may be familiar with these if you’ve used basic photo-editing software—the team then checks that the stretch worked and a range of brightness is now visible. 
Refining the Filtered Images

The next step is to adjust the tonality of the image to further enhance the signal and detail in each filter while minimizing background noise. They also have to remove “artifacts” like cosmic rays or “persistence,” which is when a star is so bright that it leaves residual marks in successive observations. This requires sampling the background noise and swapping out the affected values. 

“You can think of it as replacing the ‘bad pixels’ with the average value near it,” Pagan says. 
Assigning Colors by Wavelength

At that point, the image begins to show points of light and areas that look clear or hazy, but no color yet. That comes next. Working within the infrared data, the team prescribes red to the longest wavelengths, green to the mid-range ones, and blue to the shortest wavelengths— translating differences within the invisible spectrum into colors that we recognize, and allowing them to mix to form unique color values. The now-colorful image is not yet in its final form, but it’s getting closer. 

“It’s the different subtle variations from filter to filter that allow colors to show through,” DePasquale says. 
Initial Composited Image

After colors are assigned to the filtered images, they are merged into one file that will be further revised after team discussions. 

In consultation with the scientists who will study the images, the team then focuses on color calibration and balance, as well as tonality, contrast, and composition—just like in standard, Earth-based photography. The result is the images visible to people around the world on July 12. 
Final Image of the Carina Nebula

This landscape of “mountains” and “valleys” speckled with glittering stars is actually the edge of a nearby, young, star-forming region called NGC 3324 in the Carina Nebula. Captured in infrared light by NASA’s new James Webb Space Telescope, this image reveals for the first time previously invisible areas of star birth.

Credits: NASA, ESA, CSA, and STScI

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