Webb telescope found a Milky Way lookalike 12 billion light-years away

Researchers have discovered a large and orderly spiral galaxy which was formed shortly after the Big BangWhen space was only about 1.5 billion years old.

The galaxy, named Alaknanda, appears in observations made by NASAIt is James Webb Space Telescope as part of major sky surveys. Because the Milky Way doppelganger is seen at an extreme distance, its light has traveled for over 12 billion years to reach Earth. Only recently has telescope technology become powerful enough to spot galaxies in this level of detail at such an early time.

For decades, astronomers believed that galaxies in the early universe were too turbulent to take on neat spiral shapes. Young stars and gas were thought to move chaotically, producing irregular clusters instead of smooth disks and arms. Hubble Space Telescope observations support this view, because spiral galaxies seemed rarer beyond about 11 billion years in retrospect.

The discovery raises new questions about how such structures formed so early.

“Alaknanda reveals that the early universe was capable of assembling galaxies much faster than previously thought,” said Yogesh Wadadekar, co-author of the study, in a declaration. “Somehow, this galaxy managed to gather 10 billion solar masses of stars and organize them into a magnificent spiral disk in just a few hundred million years. That’s extraordinarily fast by cosmic standards, and it’s forcing astronomers to rethink how galaxies form.”

Webb’s sharper view revealed many disk-shaped galaxies from the early universe, and now, a small but growing number of true spiral galaxies – including Alaknanda – much 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 Alaknanda discovery, made by scientists at the National Center for Radio Astrophysics at the Tata Institute of Fundamental Research in India, was published in the journal Astronomy and astrophysics.

The research team was able to observe immense detail in Alaknanda thanks to a natural phenomenon called gravitational lensing.
Credit: NASA / ESA / CSA / I. Labbe / R. Bezanson / Alyssa Pagan / Rashi Jain / Yogesh Wadadekar

“The physical processes behind galaxy formation—gas accretion, disk sedimentation, and possibly the development of spiral density waves—may operate much more efficiently than current models predict,” Rashi Jain, the lead author, said in a statement. “This requires us to rethink our theoretical framework.”

Alaknanda – named after the Himalayan river which is a twin of the Ganges – covers approximately 32,000 hectares. light years through, comparable to large modern spiral galaxies. It also contains a large number of stars.

The images show that the galaxy already has a flat, rotating disk with two transparent spiral arms in a classic pinwheel shape. These arms appear smooth and symmetrical, earning Alaknanda the label of “high design” spiral galaxy, meaning that it has defined arms rather than uneven or broken arms.

Along the spiral arms, scientists observed chains of bright clusters of newborn stars. These clusters look like a string of pearls, 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 observe immense detail in the distant galaxy thanks to a natural phenomenon known as gravitational lens. The gravity of a huge galaxy cluster acts like a giant magnifying glass in the sky, bending and strengthening Alaknanda’s light so that it appears twice as bright.

Observing Alaknanda through different wavelengths of light allowed scientists to estimate the age of the galaxy’s stellar population and found that the stars were on average only about 200 million years old.
Credit: NASA GSFC / CIL / Illustration Adriana Manrique Gutierrez

To understand Alaknanda’s history, researchers compared its brightness across 21 different wavelengths, ranging from ultraviolet to infrared. By matching these measurements with computer models of stellar populations, they estimated that the galaxy’s stars were on average only about 200 million years old. This means that about half formed in a rapid explosion when the universe was already over a billion years old.

Alaknanda continues to grow rapidly. It forms new stars at a rate of about 63 suns per year – dozens of times faster than the Milky Way today. Some colors of light shine brighter than expected, as the glowing gas around the new stars emits strong signals, confirming the galaxy’s intense star-forming activity.

Scientists still don’t know how spiral arms formed so quickly in these ancient systems. Some theories suggest they result from slow density patterns inside the 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 this conclusion.

Future observations using Webb’s instruments to measure movements inside galaxies, as well as radio telescopes, could map how Alaknanda’s stars and gas orbit its center. This data could help determine whether its disk has reached its final configuration or whether the spiral arms represent just a simple phase of its development.