When the James Webb Space Telescope (JWST) opened its golden eyes to the universe in 2022, astronomers expected surprises. What they didn’t expect was to stumble upon tiny crimson sparks scattered across the earliest reaches of time—enigmatic “little red dots” that seemed to defy everything we thought we knew about galaxies, stars, and black holes.
The JWST is the most powerful space observatory ever built. With instruments designed to capture faint infrared light—the glow stretched by billions of years of cosmic expansion—it allows scientists to peer further back in time than ever before. Looking through Webb is like opening a portal: each photon it captures left its source billions of years ago, meaning we are seeing the universe as it was just a few hundred million years after the Big Bang.
But in those ancient depths of time, Webb spotted something baffling—objects that shouldn’t exist, at least not according to our best models.
The First Sight of the Universe Breakers
In the first wave of JWST data, researchers noticed peculiar dots glowing in shades of red, as though they were tiny embers flickering at the edge of visibility. At first glance, they seemed to be galaxies—massive ones, in fact—already in existence just 500 to 700 million years after the Big Bang.
This didn’t make sense. The early universe was supposed to be messy and chaotic, a cosmic nursery where galaxies were only beginning to take shape. Mature galaxies, like our Milky Way, were expected to take billions of years to assemble. Yet here were objects as bright and massive as galaxies that should have been far too young to exist.
The team that first reported them jokingly called them “universe breakers”—because if they truly were fully formed galaxies, they would shatter our understanding of cosmic history.
Galaxies… or Something Else Entirely?
As scientists studied the little red dots more closely, doubts began to grow. The brightness and compactness of these objects didn’t quite add up. If they were galaxies, the stars inside them would have to be packed with impossible density, creating night skies so blinding that an inhabitant’s every glance upward would reveal dazzling sheets of starlight.
That kind of density seemed unrealistic. The data hinted at something stranger, something the astrophysicists had never considered before.
By 2024, after analyzing nearly 60 hours of Webb observations and spectra from over 4,500 distant galaxies, the research team—an international collaboration including Penn State scientists—proposed a radical new explanation: the little red dots might not be galaxies at all. Instead, they could be an entirely new class of cosmic object—black hole stars.
What Is a Black Hole Star?
At first, the phrase sounds like a contradiction. Stars shine because of nuclear fusion, while black holes devour light so completely that nothing escapes. How could such opposites coexist?
A “black hole star” isn’t a normal star at all. Imagine a supermassive black hole forming in the very young universe, billions of times heavier than our sun. As it pulls in gas from its surroundings, the inflowing material doesn’t just vanish—it heats up, forming a vast, dense, glowing atmosphere around the black hole itself.
To an observer, it would look like a star: a gigantic sphere of gas radiating light. But unlike ordinary stars, its core isn’t a nuclear furnace. Its heart is a black hole, swallowing matter with ferocious hunger and spitting out radiation as energy.
Joel Leja, an astrophysicist at Penn State and co-author on the study, explained it simply: “We thought it was a tiny galaxy full of many separate stars, but it’s actually one gigantic, very cold star.”
The Cold Light of the Red Dots
Here’s another twist: the gas around these black hole stars glows not with the blistering temperatures we usually associate with matter falling into a black hole—millions of degrees—but instead with surprisingly cool light.
Cold stars are dim and red, their glow shifted into the infrared part of the spectrum. Normally, these stars are hard to see, drowned out by brighter, hotter neighbors. But Webb’s infrared vision is perfectly tuned to detect them.
The little red dots Webb spotted were giving off light consistent with cold gas atmospheres, just like the surfaces of low-mass stars. Except in this case, that glow was being produced not by nuclear reactions, but by a black hole’s feeding frenzy cloaked in a giant ball of gas.
The Cliff: A Cosmic Outlier
Among the many red dots studied, one stood out. Nicknamed The Cliff, it became the poster child of this new class of object.
Light from The Cliff traveled nearly 12 billion years to reach us. When Webb broke down that light into a spectrum, it revealed a shocking story: the object had an immense amount of mass, far too much to be explained by normal stars packed into a young galaxy.
Instead, the data pointed toward a supermassive black hole shrouded in a cocoon of hydrogen gas, glowing faintly red as it gorged on matter. To the scientists, The Cliff was the first convincing case that these little red dots weren’t galaxies at all, but black hole stars in disguise.
“The extreme properties of The Cliff forced us to go back to the drawing board and come up with entirely new models,” said Anna de Graaff of the Max Planck Institute for Astronomy, who led the study.
The Birth of Giants
If these black hole stars are real, they may finally help solve one of astronomy’s biggest puzzles: where do supermassive black holes come from?
Today, nearly every galaxy—including our own Milky Way—has a gigantic black hole lurking at its center, millions or even billions of times heavier than the sun. But no one knows exactly how such monsters formed so early in cosmic history.
Black hole stars could be the missing link. In this model, the little red dots are the baby pictures of today’s cosmic giants—newborn supermassive black holes, rapidly gaining mass in their infancy, wrapped in thick gaseous cocoons. As the gas eventually thins, the black hole remains, becoming the gravitational anchor around which galaxies grow.
In this sense, galaxies may not come first. Black holes may come first, and galaxies might form around them. It’s a radical reversal of our usual picture of cosmic evolution.
Following the Universe’s Clues
The discovery is still tentative. As Joel Leja himself admitted: “This is the best idea we have and the first that fits nearly all of the data. But it’s okay to be wrong. The universe is much weirder than we can imagine.”
The little red dots are so distant, so faint, and so compact that even Webb struggles to pin them down. More data will be needed to confirm the black hole star hypothesis—spectra from more red dots, better models, and perhaps even observations from the next generation of telescopes.
But whatever they turn out to be, the discovery already illustrates the power of Webb: in just its first few years, it has forced scientists to rethink the early universe, rewriting chapters of cosmic history that were once thought complete.
The Cosmic Poetry of Surprise
Astronomy is often described as humanity’s oldest science, but it is also the science most defined by wonder. Each time we think we’ve reached the limits of understanding, the cosmos offers a twist.
The little red dots remind us that the universe is not a static textbook, but a living mystery. They tell us that galaxies may not have formed the way we imagined, that black holes may be stranger than the monsters we already know, and that the early universe was a playground for exotic objects beyond our dreams.
Most of all, they remind us that curiosity is the compass that guides us through the unknown. As we look deeper into space, and further back in time, we are not just mapping the universe—we are rediscovering our own capacity for wonder.
The next time you look at the night sky, remember: somewhere in those distant, ancient depths, there may be red dots flickering—colossal black hole stars, strange and luminous, whispering the secrets of the universe’s earliest days.
More information: Anna de Graaff et al, A remarkable ruby: Absorption in dense gas, rather than evolved stars, drives the extreme Balmer break of a little red dot at z = 3.5, Astronomy & Astrophysics (2025). DOI: 10.1051/0004-6361/202554681
