Plate Nº 61 · recorded October 10, 2026
Space & AstronomyReported finding
Webb Telescope Spots Mars-Sized Worlds Smashing Together
NASA's Webb telescope has identified 21 rare debris disks whose chemical fingerprints reveal violent collisions between rocky bodies, including Mars-sized impacts that may mirror the event that formed the Moon.
By Elena Vasquez3 min read689 words
In brief
- Findings published October 1, 2026, in The Astrophysical Journal
- Researchers studied 21 extreme debris disks: 5 from archival Spitzer data and 16 with Webb (12 new and 4 follow-ups)
- Roughly one-third of the disks show silica-rich dust tied to Mars-sized body collisions; two-thirds are silica-poor from gentler Moon-sized impacts
- Silica-rich disks appear only around stars younger than 300 million years
- Only about 1% of young stars display observable signs of an extreme debris disk phase
NASA's James Webb Space Telescope has identified 21 star systems whose warm dust belts bear the chemical fingerprints of recent, violent collisions between rocky bodies — roughly one-third of which involved Mars-sized worlds smashing together with enough force to vaporize rock.
How did astronomers identify the collisions?
Astronomers published the findings on October 1, 2026, in The Astrophysical Journal. The work builds on long-standing theories about the cataclysmic impact that likely created Earth's Moon, when a Mars-sized body called Theia struck the young Earth and hurled vaporized rock into orbit.
The team, led by Kate Su of the Space Science Institute in Boulder, Colorado, focused on a rare class of objects called "extreme debris disks." These systems hold unusually large amounts of warm dust close to their host stars, in roughly the zone where rocky planets orbit our Sun.
The disks are uncommon. Only about 1% of young stars display observable signs of this phase. The researchers drew 5 systems observed by the older Spitzer Space Telescope and 16 observed with Webb — 12 new and 4 follow-ups.
"This is the first time we have gathered enough systems to truly understand this subclass that we call extreme debris disks," Su said. "Before Webb, we had limited information. We knew that they are weird and very different from the typical cold debris disks that we know, like Vega and Fomalhaut."
What can dust tell us about planetary impacts?
Webb's mid-infrared spectrometer revealed three defining traits:
- Smaller dust grains than those in typical debris disks
- High concentrations of warm dust
- Irregular changes in infrared brightness over time
Mineral composition then split the sample into two groups. About one-third are silica-rich, with dust resembling volcanic glass such as obsidian. The remaining two-thirds are silica-poor, dominated by minerals like forsterite, the green sand on some Hawaiian beaches.
Silica-rich dust likely forms in energetic collisions between Mars-sized bodies. Silica-poor dust appears to come from gentler events, including grazing impacts between Moon-sized objects.
The team's age analysis supports this division. Silica-rich disks appear only around stars younger than 300 million years. Silica-poor disks span a wider age range and tend to fluctuate more in brightness.
"To just see their mid-infrared emission and beautiful spectral features with Webb, which allowed us to identify their compositions, was the most exciting thing for me," said Agnes Kospal of Konkoly Observatory in Budapest, a coauthor.
Could our own solar system have passed through this phase?
The timeline fits. Computer models suggest terrestrial planets form within the first few hundred million years after a star ignites, roughly the age range of the silica-rich disks. The Moon itself likely formed about 100 million years after the Sun, in the same kind of impact the silica-rich disks appear to record.
The older silica-poor disks may preserve a different chapter. Their erratic infrared brightness could reflect orbital instability, a pattern broadly consistent with the Late Heavy Bombardment hypothesis. Under that scenario, the giant planets shifted position and triggered brief, catastrophic waves of collisions throughout the inner solar system.
"How rocky planets formed and giant planets evolved are part of the broader story of the solar system's formation. It's all one story," Su said.
Coauthor Attila Moor of Konkoly Observatory added a note of caution: "Of course, there's many things we still don't know about these disks. We only have three disks in our sample that fit that age criteria, so it'll be nice to observe more of these systems to confirm our hypothesis."
What remains uncertain?
The conclusions rest on a sample of just three silica-rich disks in the relevant age range. Larger surveys will be needed to confirm that older stars never host silica-rich systems, and to test whether solar-system-style bombardments really do produce the fluctuating brightness astronomers now see.
Even so, Webb's first systematic look at extreme debris disks gives planetary researchers a concrete catalog of the kinds of collisions that may once have shaped our own cosmic neighborhood.
via dx.doi.org (Original)
More from Elena Vasquez
Nearby plates
- Webb Telescope Witnesses Planet-Smashing Collisions Around Young Stars
- New Simulations: The Moon May Have Formed Intact in Five Hours
- Millions of Planets Could Orbit Supermassive Black Holes, Simulations Show
- JWST Survey of 72 Young Stars Maps How Planet-Forming Gas Escapes
- Simulations Reconstruct How the First Stars Forged the Universe