In the quiet archive of 200,000 Hubble images, astronomers searching for nothing in particular found something that should not be there — a faint, sourceless glow wrapping the entire solar system like an invisible lantern. After removing every known light source from the data, a residue of illumination remained, equivalent to ten fireflies spread across the whole of the night sky. The discovery, emerging from Arizona State University's SKYSURF project, suggests that a previously unmeasured shell of comet-born dust surrounds our planetary neighborhood, quietly rewriting what we thought we knew
Hubble discovers mysterious glow surrounding solar system
an eerie glow that persists after all known light sources are accounted for
Mark
So they looked at 200,000 Hubble images and found light that shouldn't be there. How do we know it's really there and not just an artifact of the measurement?
Mimi
They systematically removed every known light source—planets, stars, galaxies, dust in the solar plane. What was left was a consistent excess. It's equivalent to ten fireflies spread across the entire sky. That's tiny, but it's real and reproducible.
Luke
But how confident are we in the elimination process? If you're filtering out 95 percent of photons and keeping 5 percent, the margin for error has to be enormous. What's the uncertainty band on that measurement?
Mimi
That's fair. The team published their methodology in peer-reviewed journals, so the filtering process is transparent. But you're right—this is a faint signal, and independent verification will matter.
Mark
They think it's dust from comets. How does that dust stay in place? Wouldn't it drift away or get blown out by solar wind?
Mimi
Comets are constantly falling into the solar system from all directions. The dust they shed as they approach the sun creates a kind of ongoing halo. It's not static—it's being replenished.
Luke
But that's still a hypothesis. They haven't directly observed this dust shell. They've observed light and proposed an explanation. What other explanations are on the table?
Mimi
The New Horizons spacecraft detected a different glow farther out, and that one might be dark matter annihilation. But Carleton's team thinks their glow is closer in, from inside the solar system. So there could be multiple sources.
Mark
What does this actually change about how we understand the solar system?
Mimi
It suggests the solar system has a structural component we've never quantitatively measured before. That's significant for models of planetary formation and the long-term evolution of our neighborhood.
Luke
But we still don't know for certain what it is. We have a detection and a leading hypothesis. That's progress, but it's not closure.
Mimi
Exactly. This is the beginning of a conversation, not the end of one.
The Pulse
- Astronomers expected silence after stripping away every known light source — instead, they found a persistent, unexplained glow haunting the entire sky.
- The eerie residue, faint as ten fireflies scattered across the cosmos, resists every conventional explanation and points to something hiding in plain sight around our own solar system.
- The leading theory implicates comets falling toward the sun, shedding dust that forms an invisible spherical shell reflecting sunlight back toward Earth — a structural feature of the solar system never before measured.
- The mystery deepens because NASA's New Horizons probe detected a separate unexplained glow from billions of miles farther out, suggesting the two phenomena may be distinct and layered upon each other.
- Researchers are now confronting the possibility that solar system models require fundamental revision, and that decades of Hubble data dismissed as noise may hold further hidden discoveries.
In the quiet archive of 200,000 Hubble images, astronomers searching for nothing in particular found something that should not be there — a faint, sourceless glow wrapping the entire solar system like an invisible lantern. After removing every known light source from the data, a residue of illumination remained, equivalent to ten fireflies spread across the whole of the night sky. The discovery, emerging from Arizona State University's SKYSURF project, suggests that a previously unmeasured shell of comet-born dust surrounds our planetary neighborhood, quietly rewriting what we thought we knew about the architecture of home.
Astronomers have found a faint, persistent glow surrounding the solar system — one that refuses to disappear even after every known source of light has been methodically removed from view. The discovery came through SKYSURF, an ambitious project led by researchers at Arizona State University, in which 200,000 Hubble Space Telescope images were combed for overlooked information. After filtering out planets, stars, galaxies, and known dust, a tiny excess of light remained — equivalent, in total brightness, to ten fireflies spread across the entire night sky.
Lead researcher Tim Carleton described the finding as evidence of "a new element to the contents of the solar system that has been hypothesized but not quantitatively measured until now." NASA offered a vivid analogy: it is like entering a darkened room, drawing all the shades, switching off every light — and still finding the walls faintly glowing. The most plausible explanation is that comets falling toward the sun release dust and ice as their surfaces sublimate, and that this material has accumulated into a diffuse shell around the solar system, gently reflecting sunlight back toward Earth.
The discovery is not entirely without precedent. In 2021, NASA's New Horizons spacecraft — now traveling 4 to 5 billion miles from the sun — also detected an unexplained background glow. One hypothesis ties that signal to dark matter annihilation at the solar system's far edge. Carleton, however, believes the two phenomena are distinct: the SKYSURF glow appears to originate from within the solar system, while the New Horizons signal comes from much farther away, suggesting the two are separate, layered mysteries.
The project itself was born from an unconventional realization. Veteran astronomer Rogier Windhorst noticed that more than 95 percent of the photons in Hubble's archive — those originating from within roughly 3 billion miles of Earth — had been routinely discarded by researchers focused on distant objects. By treating that overlooked light as data rather than noise, the team uncovered a hidden dimension of the solar system's composition. Published across two journals in late 2022, the research reframes the space immediately surrounding our planets as something still partly unknown, and still quietly glowing.
Astronomers have found something unexpected lurking in the darkness around our solar system—a faint, persistent glow that remains even after every known source of light has been systematically removed from view. The discovery emerged from an unusual project called SKYSURF, in which researchers combed through 200,000 images captured by the Hubble Space Telescope, methodically filtering out the light from planets, stars, galaxies, and dust particles in the solar system's plane. What remained was a tiny excess of light, equivalent to the combined glow of ten fireflies scattered across the entire night sky.
Tim Carleton, an astronomer at Arizona State University and the lead author of the research, described the finding as potentially revealing "a new element to the contents of the solar system that has been hypothesized but not quantitatively measured until now." The discovery suggests that our understanding of the solar system's structure may need revision. NASA officials offered an apt analogy: imagine walking into a darkened room, turning off all the lights and drawing the shades, only to find that an eerie glow still emanates from the walls, ceiling, and floor. That is essentially what astronomers have detected in the space surrounding our planetary neighborhood.
The most plausible explanation points to dust ejected by comets as they fall toward the sun. As these icy bodies approach our star, the intense heat causes solid material within them to sublimate—transforming directly from ice into gas—and this process releases a burst of dust and ice particles into space. Those particles, distributed smoothly in all directions around the solar system, would reflect sunlight back toward Earth, creating the observed glow. Such a shell of dust would represent an entirely new architectural feature of the solar system, one that has never been quantitatively measured before.
This is not the first time astronomers have detected an unexplained background glow in the solar system. In 2021, NASA's New Horizons spacecraft, which flew past Pluto in 2015 and is now traveling toward interstellar space at a distance of 4 billion to 5 billion miles from the sun, also measured a faint background light that remains unexplained. One hypothesis suggests that glow originates from dark matter particles annihilating each other far outside the solar system. However, Carleton noted a crucial distinction: the light detected by New Horizons appears to come from farther away than the glow discovered by the SKYSURF team. "If our analysis is correct, there's another dust component between us and the distance where New Horizons made measurements," he said. "That means this is some kind of extra light coming from inside our solar system."
The project itself emerged from an unconventional insight. Rogier Windhorst, a veteran astronomer at Arizona State University, recognized that Hubble's archive contained valuable information that most researchers had been overlooking. More than 95 percent of the photons captured in Hubble images originate from distances less than 3 billion miles from Earth, yet astronomers had routinely discarded this data, focusing instead on distant stars and galaxies. By treating these overlooked photons as a resource rather than noise, Windhorst and his team uncovered a hidden layer of the solar system's composition.
The research, published in two papers in the Astronomical Journal and the Astrophysical Journal Letters in October and November, represents a methodical detective work—the systematic elimination of known light sources to reveal what remains. What remains is a mystery with a rational explanation, but one that fundamentally changes how astronomers think about the space immediately surrounding Earth and the other planets. The discovery opens new questions about the dust and debris that populate the solar system and may eventually help explain the earlier, still-mysterious glow detected by New Horizons at the edge of interplanetary space.
Notable Quotes
It may be a new element to the contents of the solar system that has been hypothesized but not quantitatively measured until now.— Tim Carleton, astronomer at Arizona State University
If our analysis is correct, there's another dust component between us and the distance where New Horizons made measurements. That means this is some kind of extra light coming from inside our solar system.— Tim Carleton
Want the full story?
Read the original at Space.com ↗
Science & Space