Webb telescope found a Milky Way lookalike 12 billion light-years away
Researchers have discovered a large, orderly spiral galaxy that formed soon after the Big Bang, when space was only about 1.5 billion years old.
The galaxy, named Alaknanda, appears in observations made by NASA’s James Webb Space Telescope as part of major sky surveys. Because the Milky Way lookalike is seen at an extreme distance, its light has traveled for more than 12 billion years to reach Earth. Only recently has telescope technology become powerful enough to spot galaxies with this level of detail from such an early time.
For decades, astronomers believed galaxies in the early universe were too turbulent to settle into neat spiral shapes. Young stars and gas were thought to move chaotically, producing irregular clumps instead of smooth disks and arms. Hubble Space Telescope observations supported this view, as spiral galaxies seemed more scarce beyond about 11 billion years in look-back time.
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The discovery raises new questions about how such structures formed so early.
"Alaknanda reveals that the early universe was capable of far more rapid galaxy assembly than we anticipated," said Yogesh Wadadekar, the study's co-author, in a statement. "Somehow, this galaxy managed to pull together 10 billion solar masses of stars and organise them into a beautiful spiral disk in just a few hundred million years. That's extraordinarily fast by cosmic standards, and it compels astronomers to rethink how galaxies form."
Webb’s sharper vision has revealed many disk-shaped galaxies from the early universe, and now, a small but growing number of true spiral galaxies — including Alaknanda — far earlier than predicted by older models. The telescope found CEERS-2112 and REBELS-25, two spiral galaxies, in the early universe in 2023 and 2024, respectively.
The discovery of Alaknanda, made by scientists at the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research in India, has been published in the journal Astronomy & Astrophysics.
"The physical processes driving galaxy formation — gas accretion, disk settling, and possibly the development of spiral density waves — can operate far more efficiently than current models predict," said Rashi Jain, the lead author, in a statement. "It's forcing us to rethink our theoretical framework."
Alaknanda — named after the Himalayan river that is a twin headstream of the Ganga — spans roughly 32,000 light-years across, comparable to large modern spiral galaxies. It also contains a huge number of stars.
Images show that the galaxy already has a flat, rotating disk with two clear spiral arms with the classic pinwheel shape. These arms appear smooth and symmetrical, earning Alaknanda the label of a "grand-design" spiral galaxy, meaning it has defined arms rather than patchy or broken ones.
Along the spiral arms, scientists observed chains of bright clumps of newborn stars. These clumps look like a string of beads, marking areas where gas has collapsed into dense pockets that ignite new stars. In other views, each string appears as part of a larger spiral arm.
The research team was able to see immense detail in the distant galaxy with the help of a natural phenomenon known as gravitational lensing. A massive galaxy cluster's gravity acts like a giant magnifying glass in the sky, bending and enhancing the light of Alaknanda to appear twice as bright.
To understand Alaknanda’s history, researchers compared its brightness across 21 different wavelengths of light, spanning ultraviolet to infrared. By matching those measurements to computer models of stellar populations, they estimated that the galaxy’s stars average only about 200 million years old. That means roughly half formed in a rapid burst after the universe was already more than 1 billion years old.
Alaknanda continues to grow quickly. It forms new stars at a rate equal to about 63 suns per year — dozens of times faster than the Milky Way does today. Certain colors of light shine brighter than expected because glowing gas around new stars gives off strong signals, confirming the galaxy’s intense star-forming activity.
Scientists still do not know how spiral arms formed so quickly in these ancient systems. Some theories suggest they arise from slow-moving density patterns inside disks, while others point to gravitational disturbances from nearby galaxies or large clumps of gas. Alaknanda even appears to have a small neighboring galaxy that could have helped trigger its spiral structure, but more evidence is needed to draw that conclusion.
Future observations using Webb’s instruments for measuring motions inside galaxies, along with radio telescopes, could map how Alaknanda’s stars and gas orbit its center. Those data could help determine whether its disk has settled into its final configuration or whether the spiral arms represent a mere phase in its development.
Topics NASA
Elisha Sauers writes about space for Mashable, taking deep dives into NASA's moon and Mars missions, chatting up astronauts and history-making discoverers, and jetting above the clouds. Through 17 years of reporting, she's covered a variety of topics, including health, business, and government, with a penchant for public records requests. She previously worked for The Virginian-Pilot in Norfolk, Virginia, and The Capital in Annapolis, Maryland. Her work has earned numerous state awards, including the Virginia Press Association's top honor, Best in Show, and national recognition for narrative storytelling. For each year she has covered space, Sauers has won National Headliner Awards, including first place for her Sex in Space series. Send space tips and story ideas to [email protected] or text 443-684-2489. Follow her on X at @elishasauers.
