Inside the Invisible Universe Captured by NASA's James Webb Space Telescope
It is a rare delight for a sequel to be as good as the original, but on July 12, the James Webb Space Telescope's second set of images certainly lived up to expectations set by its extraordinary deep field reveal the prior evening. As a matter of fact, it surpassed them by leaps and bounds.
The unveiling of that first image by President Joe Biden wasn't exactly impressive, but the image itself? Magnificent. Known as "Webb's First Deep Field," it gives astronomers a look at galaxy cluster SMACS 0723.
What you're looking at is a minuscule patch of the Southern Hemisphere sky -- equivalent to a grain of sand held up to the heavens -- yet replete with thousands of galaxies, from spirals and ellipticals to simple pinpricks of light only a few pixels wide. And thanks to a phenomenon known as gravitational lensing, it provides us with the deepest, and oldest, view of the cosmos yet -- as well as concrete proof of Albert Einstein's general relativity. That's a lot to live up to, right?
Well, even though the images released Tuesday don't reach quite so far back in space and time, they are undoubtedly profound, equal to the First Deep Field in beauty and delicately woven with exquisite cosmic detail.
Three major images make up the JWST's first full-color set.
Two focus on nebulas, huge clouds of dust and gas within which stars are sometimes born, and the other analyzes a region known as Stephan's Quintet, a frightening corner of the cosmos where five galaxies are locked in an ultimately fatal dance.
Then there's the spectral data of WASP-96 b -- a really hot, giant, gassy exoplanet -- which reveals the composition of its atmosphere in unprecedented detail. This one isn't an image like you'd expect, but arguably something even more valuable. It's a spectral dataset that helps us understand not what a spaceborne object aesthetically looks like but rather what it'd be like to stand on it. And, as they say, the book is often better than the film.
Let's break down each one and explain why the JWST's second batch of cosmic goodies is just as groundbreaking as its first peek.
Nebulas are immense clouds of dust and gas that exist at either end of a star's life. Some are home to fledgling baby stars, while others are created by their explosive deaths. But in both cases, nebulas are responsible for some of the most stunning visuals we have of our cosmos -- and through the JWST's lens, the most powerful infrared imager we've ever worked with, their marvel is only enhanced.
You can read exactly how the JWST's infrared imaging works here, but the basic principle is it can access light -- emanating across the cosmos from stars, galaxies and other luminescent objects -- that's stuck in a region of the electromagnetic spectrum invisible to our eyes. And more specifically to nebulas, that "hidden" light, so to speak, happens to be the main kind shooting through their dust clouds from whatever lies inside.
That means our pupils, and even massive telescopes like the Hubble Space Telescope, can't penetrate nebular curtains of gaseousness. They're veils that typically obscure our view of the flashy features within -- namely, stars just bursting to life or those in the process of dying. The JWST's instruments, however, easily get past them via infrared imaging to check out what's going on backstage. Plus, NASA's next-gen scope offers a much (much) better resolution than a telescope such as Hubble -- in effect, catching the internal nebula show as well as external structure with a sophisticated clarity novel to human eyes.
Now that we know what we're about to look at, let's get into it.
For its first nebula science discoveries, the JWST focused on two separate stardust clouds: The Carina Nebula, located about 8,500 light-years from Earth, and the Eight Burst Nebula, which is much closer at around 2,000 light-years away.
Starting off strong, behold: the Eight Burst Nebula. It's also known as the Southern Ring Nebula.
"This is a planetary nebula," NASA astronomer Karl Gordon said. "It's caused by a dying star that spilled a large fraction of its mass over in successive waves." These shockwaves can be clearly seen in the image, they're the pond-like ripples floating around the center that resembles a biological cell.
On the left, you'll see them a bit more clearly. That's because this side is a version of the nebular image taken by the JWST's Near-Infrared Camera, or Nircam. It's often considered the telescope's holy grail imager because it leads the charge in finding pieces of the invisible universe. In this case, Nircam helps illustrate the layers of light that connect to make up this complex system. Like a mixed-media painting, it offers a good deal of texture to showcase different facets of the Southern Ring, including those shockwaves.
And on the right is a version of the image drawn by the JWST's Mid-Infrared Instrument, or MIRI. Like it's name, MIRI's specialty is catching light from the mid-infrared region of the electromagnetic spectrum. Thanks to MIRI, we also get an exciting Easter egg in this photo.
Right in the center of the cosmic eye, there are clearly two stars present. Next to the brighter one, we can see the dying one that caused the nebula -- the dot that looks redder on the left. This star duo had been theorized to exist in the past... dancing around one another in an intergalactic waltz. But we hadn't ever been seen both together before. This is the first time.
According to NASA, the brighter star will probably eject its own planetary nebula in the future -- but until then, will continue to influence the nebula's appearance, thus giving us the vivid spectacle we see today. "As the pair continues to orbit one another," NASA says, "they 'stir the pot' of gas and dust, causing asymmetrical patterns."
Also, on that right-hand image, if you glance toward the top left, you'll see a mysterious blueish line that appears to have been flung out from the nebula. This little line has its own grand story.
"I made a bet that said 'It's part of the nebula,'" Gordon said. "I lost the bet, because then we looked more carefully at both Nircam and MIRI images, and it's very clearly an edge-on galaxy." Yep, there's an entire faraway galaxy lurking in this picture. The JWST has some tricks up its sleeve.
Next up is the Carina Nebula -- once again, courtesy of the JWST's Nircam and MIRI.
"Honestly, it took me a while to figure out what to call out in this image," NASA astrophysicist Amber Straughn said. "There's just so much going on here. It's so beautiful."
This astonishing image is technically the edge of a giant cavity within a nebula called NGC 3324, known as the Carina Nebula. It boasts an incredible wealth of emerging stellar nurseries, cosmic cliffs and individual stars that call this nebula their abode. Until now, all those cosmic sparkles and details were completely hidden from our view due to the thick dust and gas surrounding them -- but, remember, the JWST infrared cameras can literally pierce that veil of intergalactic secrets and access valuable sights within.
Decoding this image could very well shed light on how stars are formed, what kind of star-making material goes into that formation and even dissect the mechanism of violent, starry winds that affect surrounding space.
And if you're curious about all those hills, valleys and spikes? So are NASA scientists. They're kind of puzzles yet to be solved. Or as Straughn puts it, "we see examples of structures that, honestly, we don't even know what they are."
Something we do know, though, is the JWST also just gave us a groundbreaking view of an alien world. An exoplanet.
The hot, gaseous, giant exoplanet WASP-96 b is a scientific curiosity. Its parent star, WASP-96, lies about 1,120 light-years from Earth, making it the closest object in Webb's first batch of images. Here it is.
OK, though this image isn't what you'd normally think of when hoping for a planetary portrait, it's incredibly important for the field of astronomy. What you're looking at is direct spectral data of an exoplanet in a solar system beyond our own.
While we don't get a view of the planet hanging out in space by its star, this "spectra" clues us in to the ingredients that make up this alien world. What astronomers detected is striking.
The JWST's spectral analysis of WASP-96 b indicates a telltale signature of water vapor in the planet's atmosphere as well as evidence of clouds and hazes, which are tiny solid particles that sort of act like pseudo-clouds. And yes, I said water. But before you get too excited about packing up to move to WASP-96 b, a world decked-out in H2O, note this exoplanet is closer to its star than Mercury is to the sun. That means its deathly hot and all its water is not liquid. Oh, and it orbits that star every three and a half Earth days.
This is probably (definitely) not habitable for us Earthlings.
Regardless, it's an intriguing finding because while astronomers have, so far, located over 5,000 worlds outside of our solar system -- and studied many of them with Hubble and other space telescopes -- WASP-96 b always stood out for its potentially unusual atmosphere. But until now, we didn't have a good look at that planetary shield, making WASP-96 b a hot topic for debate.
"Most close-in exoplanets that have been studied with Hubble have flat, white spectra, which is taken as evidence that they are very cloudy," Benjamin Pope, a planetary scientist at the University of Queensland in Australia, said. But such clouds are a nuisance because they prevent astronomers from getting a good feel for the composition of an exoplanet's atmosphere. That's not a problem with WASP-96b, so previous data suggested it was basically free of clouds. "It has the clearest skies of any exoplanet we know of," said Coel Hellier, an astrophysicist at Keele University who was a member of the team that first discovered the planet, prior to the release of the spectra.
Webb's shown that, with better data, we've been able to resolve some of the questions around WASP-96b. Like... maybe it does have clouds!
But in the grand scheme of things, this spectral data can be thought of as proof of concept that the JWST works as we hoped. Which means it will be able to assess the composition of many planets' atmospheres in the future. "[WASP-96 b] is nothing like our solar system planets," Knicole Colon, an astrophysicist at NASA said. "But that's okay because what we're seeing is, again, the first exoplanet data from Webb. This is just the beginning."
While astronomers have long used Hubble, and other telescopes, to gather data about exoplanets and their atmospheres, there's just nothing like the James Webb Space Telescope. "JWST is just going to be so much better for this," notes Pope.
Only time will tell what comes next.
Moving on -- what can Webb teach us about galaxies? As it turns out, quite a bit. Say hello to your new galactic muses.
Last but absolutely not least for NASA's Tuesday JWST image release is the breathtaking glimpse we got of Stephan's Quintet.
This dramatic grouping of five individual galaxies was discovered in the 19th century, long before the first space telescopes -- well, even the first satellites -- made it to orbit. It's a bright region of space, made up of five galaxies and home to a huge shockwave, courtesy of two galaxies colliding at extreme speed.
Of today's image releases, the Quintet is the farthest from Earth, with the galaxies located between 39 and 340 million light-years from our planet (one of the galaxies, NGC 7320, is much closer than the other four). We've been observing it from the ground for almost 150 years, and Hubble has also captured striking images of the grouping. But we've never seen it like this.
In this gigantic scene, the JWST revealed the Quintet with so much detail that we can literally see individual stars speckling the galaxies. The one on the left, in particular, is a starry spectacle fit for a fairytale universe.
But perhaps the most incredible aspect of this photo has to do with the top-most galaxy that appears violent, yet awfully serene. This duality is because it turns out to hold one of the most terrifying, yet majestic, features of the universe. A black hole.
The JWST confirmed that this galaxy has an active galactic nucleus -- that is, a supermassive black hole 24 million times the mass of our sun, sitting at its center. It's a void that's simultaneously pulling in material and spitting out light energy equivalent to the burn of 40 billion suns.
The JWST's Nirspec and MIRI teamed up to dissect the features of this abyss, offering proof of matter swirling around it.
And if you zoom out and peruse the background of the JWST's depiction of Stephan's Quintet, you'll catch sight of throngs of other galaxies dotting the dark canvas of space. Believe it or not, that's kind of a happy accident -- one we might want to get used to.
The JWST is so powerful and precise it's nearly impossible for it to take an image of what we'd consider "blank space." It can't help but serendipitously capture cosmic treasures. Every time.
It's just... too good.
It's also extremely efficient, which is why we can expect an unending influx of images and spectral data as incredible as the JWST's first full set, on a regular basis. "This is just the beginning," was a sentiment repeatedly brought up during NASA's Tuesday broadcast, and for good reason. This is the first page of astronomy's next grand chapter.
"Hubble's extreme deep field was two weeks of continuous work," Bill Nelson, NASA administrator said of probably the most famous image taken by the JWST's predecessor. "Imaging with Webb, we took that image before breakfast. The amazing thing about Webb is the speed at which we can churn out discoveries"
What this means is that even though Tuesday's release of JWST images was encapsulated in pomp and announced to the sound of champagne glasses clinking, everything we've seen took something like a week to put together. "We're going to be doing discoveries like this every week," Nelson said.