3I/ATLAS, an interstellar object passing through our Solar System, has sparked disagreement over whether it experienced catastrophic mass loss at perihelion or whether its jets could be explained by engineered propulsion. Avi Loeb argues the object may have fragmented or could be producing jets from small amounts of fuel, while comet experts at Lowell Observatory and others find it consistent with a normal comet. Upcoming observations as the object emerges from behind the Sun should provide the decisive evidence. The debate combines active scientific analysis, public commentary, and calls for additional data.
Scientists Clash Over 3I/ATLAS: Did the Interstellar Visitor Break Apart at Perihelion or Is It Something More?
3I/ATLAS, an interstellar object passing through our Solar System, has sparked disagreement over whether it experienced catastrophic mass loss at perihelion or whether its jets could be explained by engineered propulsion. Avi Loeb argues the object may have fragmented or could be producing jets from small amounts of fuel, while comet experts at Lowell Observatory and others find it consistent with a normal comet. Upcoming observations as the object emerges from behind the Sun should provide the decisive evidence. The debate combines active scientific analysis, public commentary, and calls for additional data.
12:45 AM, 11/13/2025Science
Scientists Clash Over the Fate of Interstellar Visitor 3I/ATLAS
The interstellar object 3I/ATLAS has reignited a heated debate among astronomers: was it a natural comet that partially disintegrated when it passed close to the Sun, or could its activity be caused by something artificial? Observations of unusual jets and apparent mass loss near perihelion — the point in the orbit closest to the Sun — have produced sharply different interpretations.
Avi Loeb's Case: Large Mass Loss or Engineered Jets
Avi Loeb, a Harvard astrophysicist who has been publicly vocal about possible nonnatural explanations for some interstellar visitors, has highlighted analyses suggesting a dramatic reduction in 3I/ATLAS's mass around perihelion. In one scenario he outlines, solar heating could have caused the nucleus to fragment into roughly 16 pieces, producing the observed debris and brightening.
Loeb also offers an alternative explanation: engineered propulsion. He argues that technological thrusters could generate visible jets while requiring far less expelled mass than a natural cometary breakup. By his estimates, engineered exhaust could reduce the required mass loss by several orders of magnitude, making the fuel a modest fraction of a hypothetical spacecraft's total mass.
Pushback From Comet Experts
Many comet scientists remain unconvinced. Researchers at Lowell Observatory told LiveScience that 3I/ATLAS currently looks like "a fairly ordinary, healthy-looking comet" with no clear signs that the nucleus has shattered. Penn State astronomer Jason Wright has been blunt, writing that planetary scientists generally do not accept Loeb's claims and arguing that the available evidence does not require an exotic explanation.
So the question is not whether 3I/ATLAS is unusual — it is, because it is interstellar — but whether there is any reason to think it is anything other than a comet.
Publicity, Non-Peer-Reviewed Papers, and Political Pressure
Loeb has published non-peer-reviewed papers and appeared frequently in mainstream media and podcasts to discuss these ideas. He has criticized some colleagues publicly and has sought additional data from NASA, enlisting Representative Anna Paulina Luna to press for the release of images delayed during a government shutdown. These political and media moves have intensified attention on the object and on Loeb himself.
What Will Decide the Debate?
The most decisive evidence will come from high-quality observations as 3I/ATLAS emerges from solar conjunction. If post-perihelion images show a largely intact nucleus with relatively modest mass loss, the engineered-thruster hypothesis would gain plausibility. If the nucleus is clearly fragmented or missing a large fraction of its mass, the natural breakup explanation will be far more likely.
For now, the disagreement highlights how extraordinary claims require extraordinary evidence and how scientific debate proceeds when data are ambiguous. Observers are watching closely for new images and measurements that will clarify the object's nature.