A new look at the hidden depths of the universe

The James Webb Space Telescope uses infrared light to peer through interstellar dust, revealing a universe that even scientists find overwhelming: “It just takes your breath away.”

Published 22 Dec 2022, 10:08 GMT

Tens of thousands of never-before-seen young stars were previously shrouded in the cosmic dust of the Tarantula Nebula. NASA’s James Webb Space Telescope can penetrate through the dust clouds to see the stars due to its unprecedented resolution in infrared wavelengths. The most active region appears to sparkle with massive, pale blue stars. Scattered among them are newly formed stars, appearing red, yet to emerge from the dusty cocoon of the nebula.

Photograph by Mosaic by NASA, ESA, CSA, STScI, Webb ERO Production Team

From its perch a million miles away, NASA’s James Webb Space Telescope is revealing a universe that’s richer and more perplexing than astronomers previously imagined—a cosmos that largely hides behind a veil of dust.

The biggest space telescope in history, JWST pierces that veil by capturing infrared light. Less energetic than the light our eyes can see, infrared light passes more easily through cosmic dust, and the telescope's 21-foot-wide mirror can collect this light from some of the most distant objects in the universe.

“Interstellar dust is more like smoke. It’s smaller than the dust particles on your shelf,” says Jane Rigby, the operations project scientist for JWST. “My dad’s a firefighter, so I think about it like being in a smoky room with poor visibility.”

Webb’s Mid-Infrared Instrument (MIRI) captures a thunderstorm of gas and dust in the iconic Pillars of Creation. When knots of gas and dust form in these regions, they can collapse under their own gravity, slowly heat up, and eventually form new stars.

Photograph by Image by NASA, ESA, CSA, STScI; IMAGE PROCESSING: Joseph DePasquale (STScI), Alyssa Pagan (STScI)

In contrast, Webb’s Near-Infrared Camera (NIRCam) is able to peer through the dusty pillars to show newly formed stars in shades of pink, red, and crimson. Near-infrared light can penetrate thick dust clouds, allowing astronomers to learn more about this incredible scene. The pillars are a small region within the Eagle Nebula, a vast star-forming region 6,500 light-years from Earth.

Photograph by Image by NASA, ESA, CSA, STScI; IMAGE PROCESSING: Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI)

With its infrared eye, JWST can peer through the wildfires of the universe. Launched less than a year ago and fully operational for only six months, the telescope is already revealing a startling array of cosmic objects.

During a recent meeting at the Space Telescope Science Institute in Baltimore, scientists shared some of the first results from the observatory. Those included the distances to some of the farthest galaxies yet discovered, newly observed ancient star clusters, a cloud of water surrounding Saturn’s moon Enceladus, and symmetric dust shells enveloping a big, blustery star—puffs of particles that are regularly blown out by the star itself.

Shells of cosmic dust appear like tree rings around the star Wolf-Rayet 140 in this JWST image. Wolf-Rayet stars are at an advanced stage of their lifecycles, releasing heavy elements into space, and this one is part of a binary system with an O-type star, one of the most massive star types known. The remarkable regularity of the shells' spacing indicates that the layers form like clockwork during the system's eight-year orbit, when the two stars in the binary make their closest approach to one another.

Photograph by Image by NASA, ESA, CSA, STScl, JPL, Caltech

Thomas Zurbuchen, NASA’s chief of science, says that watching JWST peer through cosmic dust is a bit like watching the clouds clear from atop a mountain in his native Switzerland.

“All of a sudden, the fog lifts and your heart just beats faster,” he says. “It just takes your breath away. You see nature in incredible colours—and it’s more beautiful than you ever imagined.”

The winding spiral structure of the galaxy IC 5332 is revealed in ultraviolet and visible light captured by the Hubble Space Telescope. Dark, dusty regions seem to separate the spiral arms.

Photograph by Image by ESA, Webb, NASA & CSA, J. Lee and the PHANGS-JWST and PHANGS-HST Teams

Using Webb’s mid-infrared instrument (MIRI), those same dusty regions are no longer dark. Webb is able to peer through the dust and see the “bones” of the galaxy.

Photograph by Image by ESA, Webb, NASA & CSA, J. Lee and the PHANGS-JWST and PHANGS-HST Teams

Other images from the space observatory capture distant and primordial parts of the cosmos, like the first publicly released image: a small patch of sky studded with countless ancient galaxies. To make that image, the telescope stared into the darkness for 12.5 hours, collecting infrared light that had been traveling through space for billions of years.

“The reason I was so emotionally overwhelmed by it was the recognition that what I’m looking at has always been there—for billions of years—almost an overwhelmingly long time, and yet we hadn’t seen it,” Zurbuchen says. “This is the beginning of a journey into the unknown, with a new set of eyes.”

The ALMA Observatory detected dust (red) in the center of the debris from Supernova 1987A, suggesting that such stellar explosions are factories for cosmic dust. Visible light (green) from Hubble, and x-rays (blue) from the Chandra X-ray Observatory show the expanding shockwave from the supernova. Supernovas such as SN 1987A can stir up the surrounding gas and trigger the formation of new stars and planets enriched with elements such as carbon, nitrogen, oxygen, and iron—the basic components of all known life.

Photograph by Composite by X-ray: NASA, CXC, SAO, PSU, D. Burrows et al.; Optical: NASA, STScI; Millimeter: NRAO, AUI, NSF)

Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This image is a composite using three NASA observatories in three different wavelengths of light: infrared data from the Spitzer Space Telescope (red), visible data from Hubble (yellow), and x-ray data from Chandra (green and blue).

Photograph by Image by NASA, JPL-Caltech, STScI, CXC, SAO Animation: NASA, JPL-Caltech, Univ. of Ariz., STScI, CXC, SAO

The James Webb Space Telescope peers into the heart of M74, otherwise known as the Phantom Galaxy. Webb’s infrared vision reveals delicate filaments of gas and dust in the grandiose spiral arms that wind outwards from the center. A lack of gas in the center provides an unobscured view of the star cluster at the galaxy's core.

Photograph by Image by ESA, Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team