Webb Finds 10-Micron Amorphous Silicates in 3I/ATLAS Dust as Ancient Interstellar Object Defies Comet Norms
Updated
Updated · Avi Loeb – Medium · Jun 30
Webb Finds 10-Micron Amorphous Silicates in 3I/ATLAS Dust as Ancient Interstellar Object Defies Comet Norms
3 articles · Updated · Avi Loeb – Medium · Jun 30
Summary
A new Webb-based preprint delivers the first spectroscopic mineralogical analysis of dust from interstellar object 3I/ATLAS, identifying a strong 10-micron feature that points to amorphous silicates.
That dust differs from typical Solar System comets, which usually show substantial crystalline silicates, and instead more closely matches material in the interstellar medium.
The result strengthens the case that 3I/ATLAS formed in a cold, distant region of its home system with little mixing of star-heated silicates into its outer disk.
Earlier Webb and ALMA studies had already dated 3I/ATLAS to roughly 10-12 billion years ago and found unusually high deuterium and carbon monoxide, making the new dust signature another clue to its ancient, atypical origin.
What secrets about the early universe are locked inside this 12-billion-year-old visitor from another star?
Is our solar system's turbulent formation a cosmic rarity compared to this ancient visitor's pristine home?
We missed the oldest object ever seen. Are our spacecraft fast enough to catch the next interstellar guest?
3I/ATLAS—The Third Interstellar Object: What Its Chemistry Reveals About Alien Worlds and the Early Galaxy
Overview
On July 1, 2025, astronomers announced the discovery of Comet 3I/ATLAS, first detected by the ATLAS survey telescope and officially designated as an interstellar comet. Its incredible speed and hyperbolic trajectory confirmed its origin from beyond our solar system, sparking immense scientific interest. Astronomers quickly determined that 3I/ATLAS poses no threat to Earth, as it will pass at a safe distance. This rare event has launched a global effort to study the comet’s unique chemistry and ancient origins, offering a valuable opportunity to learn about the building blocks of planets and the diversity of planetary systems across the galaxy.