Astronomers have made a groundbreaking discovery: Andromeda XXXV, the smallest and faintest galaxy ever observed. Located three million light-years away, this miniature galaxy orbits the Andromeda Galaxy and challenges existing theories of galactic evolution. Given its extreme smallness—only a millionth the size of the Milky Way—scientists are stunned that it survived in the chaotic early universe.
The findings, published in The Astrophysical Journal Letters, suggest that dwarf galaxies like Andromeda XXXV may have found ways to resist cosmic destruction, rewriting what we know about how galaxies form and evolve. The research was led by Marcos Arias from the University of Michigan, who, along with his team, used the Hubble Space Telescope and extensive astronomical datasets to uncover this celestial oddity.
A Tiny Galaxy That Defies Expectations
Dwarf galaxies are not new to astronomers—our Milky Way has dozens of them in its orbit. However, spotting them around other bright galaxies, such as Andromeda, has been much more difficult. Most dwarf galaxies detected before were relatively large and bright, reinforcing the theories formed from Milky Way-based observations.
Andromeda XXXV, however, changes everything. It is the smallest and dimmest galaxy ever recorded, yet it remains a fully functional galaxy.
“These are fully functional galaxies, but they’re about a millionth of the size of the Milky Way,” said Eric Bell, a team member and professor at the University of Michigan. “It’s like having a perfectly functional human being that’s the size of a grain of rice.”
This discovery forces astronomers to rethink what they believed about how small galaxies can survive the harsh conditions of the universe.
Why Should This Galaxy Have Been Destroyed?
In the early universe, conditions were extreme—filled with intense heat, powerful radiation, and violent cosmic events. Most tiny galaxies were thought to have been “fried” during this period, their gas burned away before they could form stable structures.
Yet, Andromeda XXXV somehow survived. It continues to exist despite the odds, meaning our understanding of how galaxies evolve may be incomplete.
“It was really surprising,” Bell admitted. “It’s the faintest thing you find around, so it’s just kind of a neat system. But it’s also unexpected in a lot of different ways.”
Scientists theorize that Andromeda XXXV might have developed protective mechanisms, or its environment allowed it to retain enough gas to continue forming stars billions of years after other galaxies of its size were wiped out.
A Galactic “Murder Mystery”: Why Did Some Tiny Galaxies Die While Others Survived?
One of the biggest questions in galactic evolution is why some galaxies stopped forming stars billions of years ago, while others—like Andromeda XXXV—continued for much longer.
For the Milky Way’s dwarf galaxies, astronomers believe that their gas supply simply ran out, preventing further star formation. But for Andromeda’s dwarf galaxies, the situation is different—their parent galaxy may have actively “killed” them by stripping them of their gas through gravitational forces.
This has led astronomers to describe it as a “galactic murder mystery.” Did these tiny galaxies naturally fade out, or were they pushed to extinction by their larger host galaxies?
If Andromeda XXXV was able to hold onto its star-forming gas for longer, it might explain how it survived when others didn’t. Scientists are now eager to find more galaxies like it to determine whether it is an anomaly or part of a larger, previously unseen pattern.
What This Discovery Means for Our Understanding of the Universe
The discovery of Andromeda XXXV has profound implications for how we understand galaxy formation, survival, and the evolution of the cosmos. It raises new questions about how galaxies interact with their surroundings and how some can persist in conditions that should have destroyed them.
Astronomers now hope to discover more miniature galaxies using future space missions and next-generation telescopes. If more galaxies like Andromeda XXXV are found, it could reshape the way we think about galaxy formation and even provide new insights into how our own Milky Way came to be.
“We still have a lot to discover,” said Marcos Arias, the study’s lead author. “There are so many things that we still need to learn—even about what’s near to us—in terms of galaxy formation, evolution, and structure before we can reverse-engineer the history of the universe.”
With each new discovery, the universe continues to challenge our expectations—and Andromeda XXXV is no exception.
