JWST finds a Milky Way twin born shockingly early in the Universe

NASA's James Webb Space Telescope (JWST), which can detect extremely faint and distant light, made the find possible. With its powerful infrared vision, researchers Rashi Jain and Yogesh Wadadekar observed a system that closely resembles the Milky Way, even though it formed when the Universe was roughly a tenth of its current age. They named the galaxy Alaknanda, inspired by a Himalayan river that is one of the twin headstreams of the Ganga alongside the Mandakini, a name that also happens to be the Hindi word for the Milky Way.

This work was conducted at the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research (NCRA-TIFR) in Pune, India, and the results appear in the European journal Astronomy & Astrophysics.

Why This Galaxy Should Not Exist So Early

Astronomers typically expect early galaxies to look chaotic and irregular rather than structured and stable. Classic spiral galaxies with two well-shaped arms (known as a 'grand-design' spiral) are thought to require several billion years to fully develop. Forming such a galaxy involves slow, steady gas accretion, the settling of that gas into a rotating disk, and the emergence of density waves that sculpt spiral arms. On top of that, the system must avoid major collisions that could disrupt or destroy its delicate structure.

Alaknanda does not fit this pattern at all. It already displays two prominent, sweeping arms that encircle a bright central bulge, stretching across about 30,000 light-years. It is also forming stars at an exceptional pace, creating the equivalent mass of about 60 Suns each year. That rate is about 20 times faster than the Milky Way today. Roughly half of the stars in Alaknanda seem to have formed within only 200 million years, which is extremely rapid on cosmic timescales.

"Alaknanda has the structural maturity we associate with galaxies that are billions of years older," says Rashi Jain. "Finding such a well-organized spiral disk at this epoch tells us that 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. It's forcing us to rethink our theoretical framework."

How Gravitational Lensing Helped Reveal Alaknanda

Alaknanda appears in the direction of a massive galaxy cluster known as Abell 2744, or Pandora's Cluster. The cluster's gravity bends and amplifies the light from galaxies behind it, an effect called gravitational lensing. This natural magnification made Alaknanda appear about twice as bright, giving JWST a clearer view of its spiral structure.

To study the galaxy in depth, Jain and Wadadekar examined JWST images taken through up to 21 different filters, each capturing a separate slice of its light. These observations, part of JWST's UNCOVER and MegaScience surveys, allowed the researchers to determine the galaxy's distance, the amount of dust it contains, how many stars it has formed, and how its star formation rate has changed over time with unusual precision.

A Universe That Grew Up Faster Than Expected

JWST has already revealed several surprisingly mature disk galaxies at great distances, but Alaknanda stands out as one of the clearest early examples of a classic grand-design spiral (a galaxy with two well-defined, symmetric arms). Its existence adds to growing evidence that the early Universe was far more advanced than scientists once thought.

"Alaknanda reveals that the early Universe was capable of far more rapid galaxy assembly than we anticipated," says Yogesh Wadadekar. "Somehow, this galaxy managed to pull together ten billion solar masses of stars and organize 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."

Researchers now want to understand what created Alaknanda's spiral arms. One idea is that steady inflows of cold gas allowed density waves to naturally shape the arms. Another possibility is that a smaller companion galaxy passed close enough to trigger the spiral pattern, although such tidal spirals usually fade quickly. Follow-up observations using JWST's spectroscopic instruments or the Atacama Large Millimeter Array (ALMA) in Chile could reveal whether the disk rotates smoothly (dynamically "cold") or shows signs of turbulence (dynamically "hot"), providing clues to its formation.

What This Discovery Means for Understanding Cosmic History

Alaknanda is more than an impressive image from the distant past. Its presence forces astronomers to reevaluate the timeline of cosmic evolution, including how stars, galaxies, and ultimately planets such as Earth came into existence. If galaxies could organize themselves this quickly, then the early Universe was a far more active and productive environment than previously assumed, potentially allowing planetary systems to emerge earlier than expected.

As JWST continues to push deeper into space and time, more galaxies like Alaknanda are likely to be found, each offering new insight into how rapidly the early Universe built complex structures.

The existence of Alaknanda strengthens the case that the young Universe was capable of forming stable, disk-dominated systems much earlier than scientists believed, making it one of the most distant grand-design spiral galaxies ever identified.