NASA, ESA, CSA, STScI, Webb ERO
In its short existence, the James Webb Space Telescope (JWST) has transformed our understanding of the universe. It has peered at planets, stars, galaxies and black holes, casting its eye over a cornucopia of celestial treats. It can seem like JWST arrived out of nowhere, but the telescope has been the collective effort of tens of thousands of scientists over decades. One of those scientists, Maggie Aderin-Pocock, is modest about her individual contribution, instead preferring to talk about the telescope’s fruits. “The detail the telescope can get, the wonderful resolution it gets with its six-and-a-half-metre mirror, results in some glorious images,” she says.
In her new book, Webb’s Universe: The space telescope images that reveal our cosmic history, Aderin-Pocock, presenter of The Sky At Night and chancellor of the University of Leicester, UK, catalogues these images, detailing the science behind each striking view, as well as giving a comprehensive, insider’s take on how we developed JWST’s technology. The images span a vast range of distances, from the most distant black holes from us, born near the start of the universe, to Uranus and other planets in our cosmic backyard. For each object, JWST has revealed something hidden from prior view, thanks to the unique spectrum of infrared light it can detect.
One of Aderin-Pocock’s favourite phrases to describe what she, and JWST, does is “I trip the light fantastic”, a phrase derived from poet John Milton’s description of a light and nimble dance to music. Although JWST’s manoeuvres in space can be thought of as a careful and coordinated dance, Aderin-Pocock also likes the phrase for how it intimates at the spectrum of light we can now view the universe in. “When we see the universe through these different wavelengths, we gather different bits of information – different chemical reactions and different temperatures release [different] radiation – and it’s when we put all this together that we get a better understanding of the complete picture.”
Uranus
JWST often makes headlines for its discoveries about the most distant reaches of the universe from us, but it is also in a prime position to image the planets in our own solar system, which it can see in stunning detail. “This picture sums it up,” says Aderin-Pocock. “It’s a glorious picture of Uranus. Not many people are familiar with the rings of Uranus, but all of the outer planets – Jupiter, Saturn, Uranus and Neptune – have rings. You don’t often see them in this detail and that’s because we’re looking at infrared energy.”
The Carina nebula
NASA, ESA, CSA, and STScI
The Ring nebula
ESA/Webb, NASA, CSA, M. Barlow
There is still much that astronomers don’t know about how stars are born, but the answers lie in nebulae, vast tracts of gas and dust that can span distances many times larger than our solar system. Astronomers have imaged these stellar nurseries for decades, but JWST is helping us see things we couldn’t previously. Pictured above are the Carina and Ring nebulae. “Looking with optical telescopes, not all visible light can pass through this dust and gas,” says Aderin-Pocock. “When we look at it with an infrared telescope, suddenly we see these nebulae in a very different way – we see details that we haven’t seen before.”
The Pillars of Creation
One of the most iconic images taken by the Hubble Space Telescope was a zoomed-in portion of the Eagle nebula called the Pillars of Creation, another star-forming region of gas and dust. But the image was first taken in the 1920s by astronomer John Charles Duncan, says Aderin-Pocock. JWST has now given us another view of the three columns, more than a century later. “It shows how our technology has moved on and progressed, and how each time we take a more detailed image, or an image with a different wavelength of light, we get a different understanding,” she says.
The Rho Ophiuchi cloud complex
NASA, ESA, CSA, STScI, Klaus Pon
Aside from the scientific insights, the infrared views of nearby stellar clouds, such as Rho Ophiuchi, can be inspirational on an aesthetic level. “I love this image,” says Aderin-Pocock. “To me, it looks like a really exotic bird.”
In the 1990s, astronomer Robert Williams pointed Hubble at an apparently empty patch of sky and left it to gather light for several days. The resulting image was bursting with galaxies, many of them the youngest and furthest away that we knew of. “From that, they were able to infer that, within the whole of the universe, there are about 200 billion galaxies, which slightly makes my head hurt,” says Aderin-Pocock.
Galaxy cluster SMACS 0723
NASA, ESA, CSA, and STScI
JWST has been busy making its own versions of these so-called deep-field images, such as this one of galaxy cluster SMACS 0723, looking back further in time than Hubble ever could. “Because the universe is expanding, it means wavelengths that start off as visible light, as the universe expands, get shifted into infrared light. These galaxies existed so long ago and are taking so much time [for their light] to get to us, that looking at them with an infrared gaze gives us a different insight to what they were like originally.”
The Cartwheel galaxy
NASA, ESA, CSA, STScI, Webb ERO
As well as far-away galaxies, JWST can also zoom in on individual galaxies that are closer by, and that might help shed light on how our own Milky Way formed. “If you’re a T. rex trying to take a selfie, you might get a close up of your nose, or of your ear, but it’s hard to get your full face because you can’t move the camera far enough away,” says Aderin-Pocock. The Cartwheel galaxy is the result of a collision between two smaller galaxies, but it might also help us understand the fate of the Milky Way in billions of years’ time, when it will collide with the nearby Andromeda galaxy.
RS Puppis
One of the greatest puzzles in modern cosmology is the Hubble tension, which is a clash of values when astronomers try to measure how fast the universe is expanding using different techniques. One of these is based on special stars called Cepheid variables, such as RS Puppis, which flash with extreme regularity and were first mapped in detail using the Hubble telescope. Astronomers like Aderin-Pocock hope that JWST might help image them in greater detail and reveal whether the tension is a problem with previous telescopes or is hinting at something more fundamentally broken with our model of the universe.
Galaxy cluster Abell 2744
NASA/CXC/SAO/L. Frattare & K. Arcand
We have never previously been able to look at supermassive black holes and the galaxies they reside in so early in the universe and with such rich detail. Abell 2744, a cluster of galaxies 4 billion light years from Earth also known as Pandora’s Cluster, contains at least one of these black holes. JWST’s ability to look at the gas and dust that surrounds it lets us understand how these black holes form and function which, when combined with other observations such as from X-ray telescopes, gives us a complete and detailed picture, says Aderin-Pocock.
Barnard’s galaxy, also known as NGC 6822
ESA/Webb, NASA & CSA, M. Meixner
Aderin-Pocock has spent much of her career designing instruments for space, and so knows more than most about the impressive precision and engineering built into JWST. For instance, it can focus on tiny patches of the sky, even in crowded fields of stars, using what is called a microshutter array, tiny flaps around the size of a few human hairs that can block out unwanted light. The field of stars above contains Barnard’s star, one of Earth’s closest neighbours, which was recently found to have its own planet. JWST will be studying it further.
Webb’s Universe: The space telescope images that reveal our cosmic history by Maggie Aderin-Pocock is published by O’Mara Books
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