NASA's James Webb Space Telescope (JWST) is the largest and most powerful launched into space to date.
Launched from French Guiana in December 2021, the spacecraft observes the universe from its orbit around the sun, some 1 million miles from Earth.
With its high-resolution and high-sensitivity instruments, Webb is also able to see objects that would have been either too faint or too distant to be revealed by its predecessor, the Hubble Space Telescope.
In fact—bearing in mind that light from distant stars takes time to reach us here in the solar system—the JWST is capable of seeing back a whopping 13.5 billion years, to when the universe was in its infancy.
Newsweek has rounded up six of the James Webb Space Telescope's remarkable discoveries that have astonished scientists.
The Milky Way's Heart Puts On a Show
Astrophysicists recently used the JWST to take the longest, most detailed look at the supermassive black hole at the heart of our galaxy: Sagittarius A*.
Using the telescope's Near-Infrared Camera (NIRCam), the researchers observed the behemoth for a total of 48 hours in eight- to 10-hour increments across the course of one year.
They found that Sagittarius A* is more active than anticipated, with the swirling "accretion disk" of gas and dust surrounding it emitting a constant but erratic series of flares
"In our data, we saw constantly changing, bubbling brightness," said lead researcher professor Farhad Yusef-Zadeh of Northwestern University in Illinois in a statement.
"And then boom! A big burst of brightness suddenly popped up. Then, it calmed down again. We couldn't find a pattern in this activity. It appears to be random."
The researchers believe that two processes might be at play. Short bursts around the black hole are likely caused by disturbances in the disk—compressing plasma to produce a temporary flash of radiation.
The bigger, brighter flares, the team thinks, are caused by "reconnection events," where magnetic fields release accelerated particles that emit bursts of radiation.
"The activity profile of this black hole was new and exciting every time that we looked at it," Yusef-Zadeh said.
The Knots and Whorls of Space Dust
Space is not as empty as you might think—with the space between stars in galaxies filled with vast, diffuse clouds of gas and dust known as the interstellar medium.
The JWST has recently revealed the structure of some of this material in unprecedented detail after it was warmed (and made to glow with infrared light) thanks to a shockwave from the death of the giant star Cassiopeia A.
The image of the structure of the interstellar medium the telescope has produced resembles the exquisite knots and whorls of wood grain.
"We were pretty shocked to see this level of detail," astrophysicist Jacob Jencson of the California Institute of Technology said in a statement.
Astronomer Josh Peek of the Space Telescope Science Institute in Baltimore added: "We see layers like an onion."
"We think every dense, dusty region that we see, and most of the ones we don't see, look like this on the inside. We just have never been able to look inside them before."
"Little Red Dots"
Back in December 2022—less than six months after the JWST came online—the telescope revealed a new cosmic phenomena: numerous small and mysterious red objects that were given the nickname of "Little Red Dots," thought to be a new class of galaxy.
Now, astronomers have compiled a massive catalog of Little Red Dots, all of which date back to the first 1.5 billion years after the big bang, and have found that a large proportion of these appear to contain supermassive black holes that are actively growing.
"We're confounded by this new population of objects that Webb has found," said study lead and physicist professor Dale Kocevski of Maine's Colby College in a statement.
"There's a substantial amount of work being done to try to determine the nature of these little red dots and whether their light is dominated by accreting black holes."
Kocevski explains that we don't see anything like the little red dots at lower redshifts—that is to say, closer to Earth—which is why they have only been revealed by the power of Webb.
"The most exciting thing for me is the redshift distributions. These really red, high-redshift sources basically stop existing at a certain point after the big bang," added paper co-author and astronomer professor Steven Finkelstein from the University of Texas at Austin.
"If they are growing black holes, and we think at least 70 percent of them are, this hints at an era of obscured black hole growth in the early universe."
A Long Time Ago in a Galaxy Far, Far Away
Talking of supermassive black holes, the JWST has also revealed the most distant one spotted to date. It has been detected in the heart of the galaxy "GN-z11," which lies in the constellation of Ursa Major, a whopping 32 billion light-years from Earth.
Because it is so far away, and light from GN-z11 takes time to reach the solar system, we are seeing the galaxy as it was back when our 13.8 billion-year-old universe was a relatively youthful 430 million.
GN-z11 was first spotted by the Hubble Space Telescope back in 2016—and has been puzzling scientists with its unusual brightness. Webb, however, has allowed us to determine the cause of this luminosity.
"We found extremely dense gas that is common in the vicinity of supermassive black holes accreting gas," said study lead professor and astrophysicist Roberto Maiolino of the University of Cambridge, England, in a statement.
"These were the first clear signatures that GN-z11 is hosting a black hole that is gobbling matter."
"Pool Noodles" in the Early Universe
When one thinks of galaxies, one probably pictures something like our Milky Way—broadly a flat disc with spiral arms. And most galaxies near to us (in time and space) are round too.
This was not always the case, however, the Webb telescope has revealed in a study of galaxies that formed when the universe was just 600 million to 6 billion years old.
"Roughly 50 to 80 percent of the galaxies we studied appear to be flattened in two dimensions," explained astrophysicist Viraj Pandya of New York's Columbia University.
"Galaxies that look like pool noodles or surfboards seem to be very common in the early universe, which is surprising, since they are uncommon nearby."
The reason behind this, the team believe, lies in how these flatter galaxies are precursors to more massive, round-shaped galaxies like our own.
In the early universe, galaxies had had far less time to grow," said paper co-author and astronomer Kartheik Iyer, also of Columbia.
"Identifying additional categories for early galaxies is exciting—there's a lot more to analyze now. We can now study how galaxies' shapes relate to how they look and better project how they formed in much more detail."
Congrats, It's Twins!
WL 20 is a star group that lies some 400 light-years from Earth and has been well-studied—having been observed by five different telescopes since the 1970s.
The system still has some secrets up its sleeve, however—with Webb's groundbreaking resolution and specialized Mid-Infrared Instrument (MIRI) revealing that what was long thought to be a single star, "WL 20S", is in fact a pair of them.
The twins—which are believed to have formed some 2–4 million years ago—sport two matching jets of gas that stream off into space from their north and south poles.
"Our jaws dropped. After studying this source for decades, we thought we knew it pretty well," said study author and astronomer professor Mary Barsony in a statement.
"But without MIRI, we would not have known this was two stars or that these jets existed. That's really astonishing. It's like having brand new eyes."
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Reference
Barsony, M., Ressler, M. E., Le Gouellec, V. J. M., Tychoniec, Ł., & van Gelder, M. L. (2024). Resolving Twin Jets and Twin Disks with JWST and ALMA: The Young WL 20 Multiple System. The Astrophysical Journal, 973(1), 42. https://doi.org/10.3847/1538-4357/ad5da1
Kocevski, D., Finkelstein, S., Taylor, A., Barro, G., Leung, G., Trump, J., Dickinson, M., Ceers Team, & Primer Team. (2025). JWST's Little Red Dots and the Rise of Obscured AGN at z>5. 245, 139.07. American Astronomical Society Meeting Abstracts. https://ui.adsabs.harvard.edu/abs/2025AAS...24513907K
Maiolino, R., Scholtz, J., Witstok, J., Carniani, S., D'Eugenio, F., de Graaff, A., Übler, H., Tacchella, S., Curtis-Lake, E., Arribas, S., Bunker, A., Charlot, S., Chevallard, J., Curti, M., Looser, T. J., Maseda, M. V., Rawle, T. D., Rodríguez del Pino, B., Willott, C. J., ... Sun, F. (2024). A small and vigorous black hole in the early Universe. Nature, 627(8002), 59–63. https://doi.org/10.1038/s41586-024-07052-5
Pandya, V., Zhang, H., Huertas-Company, M., Iyer, K. G., McGrath, E., Barro, G., Finkelstein, S. L., Kümmel, M., Hartley, W. G., Ferguson, H. C., Kartaltepe, J. S., Primack, J., Dekel, A., Faber, S. M., Koo, D. C., Bryan, G. L., Somerville, R. S., Amorín, R. O., Arrabal Haro, P., ... Yung, L. Y. A. (2024). Galaxies Going Bananas: Inferring the 3D Geometry of High-redshift Galaxies with JWST-CEERS. The Astrophysical Journal, 963(1), 54. https://doi.org/10.3847/1538-4357/ad1a13
Yusef-Zadeh, F., Bushouse, H., Arendt, R. G., Wardle, M., Michail, J. M., & Chandler, C. J. (2025). Nonstop Variability of Sgr A* Using JWST at 2.1 and 4.8 μm Wavelengths: Evidence for Distinct Populations of Faint and Bright Variable Emission. The Astrophysical Journal Letters, 980(2), L35. https://doi.org/10.3847/2041-8213/ada88b