Astronomers just announced the most distant – and therefore youngest – spiral galaxy yet seen in the early universe. They see it as it existed just 1 billion years after the Big Bang. Yet it has a well-defined spiral structure, a fact that goes against classical thinking about how spiral galaxies form and evolve. EarthSky’s Deborah Byrd speaks with Dr. Christina Williams at University of Arizona, one of the astronomers involved in the study. Watch in the player above, or on YouTube.
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What did our Milky Way look like in the early universe?
An international team of astronomers says it has spotted the most distant spiral galaxy yet known. They used the Webb space telescope to capture this galaxy as it existed just 1 billion years after the Big Bang. They said on April 16, 2025, that it might be a peek at what our home galaxy, the spiral-shaped Milky Way, looked like in the early universe.
Originally, astronomers thought spiral galaxies grew over billions of years from chaotic, irregular masses. But with more and more evidence mounting, it appears that galaxies like our Milky Way obtained their spiral structure much earlier than once thought.
The astronomers are calling this galaxy Zhúlóng, a name meaning Torch Dragon in Chinese mythology. As lead author Mengyuan Xiao of the University of Geneva explained:
In the myth, Zhúlóng is a powerful red solar dragon that creates day and night by opening and closing its eyes, symbolizing light and cosmic time.
The scientists published their peer-reviewed research in the journal Astronomy & Astrophysics on April 16, 2025.
Similarities to the Milky Way
The universe is nearly 14 billion years old. And we see Torch Dragon as it was 1 billion years after the Big Bang, or close to 13 billion years ago. Its light has traveled so far for so long across the universe to reach us that it has redshifted – or moved toward the red end of the spectrum – to a high degree. In fact, it has a redshift of 5.2, which makes it the highest redshift for any candidate spiral galaxy yet.
Despite what must be the galaxy’s young age, the researchers said it already shows:
a surprisingly mature structure: a central old bulge, a large star-forming disk, and spiral arms … features typically seen in nearby galaxies.
Xiao said:
What makes Zhúlóng [Torch Dragon] stand out is just how much it resembles the Milky Way in shape, size and stellar mass.
The Milky Way spans about 100,000 light-years across, comparable to Torch Dragon’s 60,000 light-years. And the newly discovered galaxy has more than 100 billion solar masses in stars. The scientists called it one of the most compelling analogues for our galaxy ever found so early in the universe.
Co-author Christina Williams of NSF NOIRLab said:
It is really exciting that this galaxy resembles a grand-design spiral galaxy like our Milky Way. It is generally thought that it takes billions of years for this structure to form in galaxies, but Zhúlóng shows that this could also happen in only one billion years.
What’s next?
The researchers found this galaxy in a wide-area survey, which Williams said:
… is essential for discovering massive galaxies, as they are incredibly rare.
The scientists hope that future observations with Webb and the and Atacama Large Millimeter Array (ALMA) will help them learn more about the galaxy. They’d like to confirm their observations and gain more information so they can understand how it formed. And, of course, they’d also like to find more giant spiral galaxies in the early universe.
Bottom line: Astronomers have discovered the oldest known spiral galaxy. It’s thought be similar to what our own Milky Way galaxy looked like, 1 billion years after the Big Bang.
Source: PANORAMIC: Discovery of an ultra-massive grand-design spiral galaxy at z ~ 5.2
Via Université de Genève
Via NOIRLab
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