Solar Heating Strips Surface of Interstellar Comet 3I/ATLAS
Researchers determined solar radiation significantly eroded the comet's surface after its discovery in July 2025.
Updated on Oct. 25, 2026 in Physics
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Interstellar comet 3I/ATLAS lost between 18 and 58 billion kilograms of material as it traveled through the solar system. Data suggests solar heating stripped a surface layer ranging from 1.7 to 5.2 meters in thickness.
Why it matters
Understanding the erosion of 3I/ATLAS helps scientists quantify how interstellar objects are altered by exposure to solar radiation. This analysis provides insight into the composition and structural integrity of bodies entering our solar system.
Researchers analyzed the velocity of substances within the comet's coma and modeled mass loss rates across its trajectory. Erosion estimates vary from 3.4 to 10.5 meters if dust mass equals gas mass, rising to 26.7 meters if dust is four times gas.
The details
The comet nucleus, estimated to have a radius of 1.3 kilometers, experienced chemical changes as cosmic radiation converted outer-layer carbon monoxide into carbon dioxide. These calculations allow scientists to map the depth of the radiation-altered zone, estimated at 15 to 20 meters.
Timeline
Interstellar comet 3I/ATLAS was first detected in July 2025.
The Big Picture
This research advances the broader study of interstellar objects entering the solar system by providing empirical erosion metrics. The findings update the theoretical framework for how radiation and heat reshape these visitors compared to known solar system bodies.
Improved models of how celestial bodies erode under extreme conditions enhance our ability to predict the behavior of potential near-Earth objects. These findings refine the tools scientists use to assess the structural stability of space-borne materials.
The takeaway
The study demonstrates how rapidly surface materials are depleted when interstellar objects reach the inner solar system. These results underscore the need for precise mass-to-gas ratio estimations when characterizing the composition of deep-space phenomena.
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