NASA Confirms 3I/ATLAS Is Comet, But Harvard Expert Spotlights 12 'Puzzles'

The anticipation surrounding the interstellar visitor 3I/ATLAS has always been shadowed by suspicion, and NASA's latest data release did little to dispel the prevailing scepticism. Discovered on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Chile, the object received the '3I' designation because it is only the third confirmed interstellar object ever detected, following 1I/'Oumuamua and 2I/Borisov.

Following delays caused by a U.S. government shutdown, NASA finally held a long-awaited press conference on Nov. 19, 2025, presenting new data on the mysterious object. However, for those looking for revelations, the message was distinctly underwhelming. The agency largely reinforced existing observations, repeating the official 'mantra' that 3I/ATLAS is simply a natural comet.

The conference, which included information and measurements from multiple high-profile telescopes -- including HiRISE, MAVEN, Hubble, Webb and SPHEREx -- offered no significant revisions to previous findings. According to Harvard Professor Avi Loeb, who attended the event, the messaging from NASA was entirely unremarkable. Loeb had predicted that the agency would likely just parrot the official position, noting, 'NASA will repeat the official mantra that 3I/ATLAS is a natural comet and that they were unable to process the data until this week because of the government shutdown'.

Official Confirmation and the Unremarkable Nature of 3I/ATLAS

The official stance confirmed at the press conference is that 3I/ATLAS exhibits behaviours typical of comets. Officials stated the object is a natural comet, shedding gas and dust and responding to gravitational forces, just as expected. They noted that the conference itself emphasised this traditional perspective, reinforcing the idea that '3I/ATLAS does what comets do, namely shed gas and dust and responds to gravity'.

Observations collected by spacecraft provided measurements of surface materials, including dust and ices of CO₂, CO and H₂O. New, albeit minor, data on the comet's composition was added by MAVEN, which detected hydrogen in the ultraviolet spectrum. Complementary or fuzzier data were also made available from Hubble, Webb, and SPHEREx relative to the HiRISE observations.

The HiRISE camera aboard the Mars Reconnaissance Orbiter captured an image of 3I/ATLAS on Oct. 3, 2025, at a spatial resolution of 30 kilometres per pixel. Yet, even this direct image was compromised. Loeb explained that due to spacecraft 'jitter' during the observation period, the light from 3I/ATLAS was smeared across several pixels, meaning the image would likely show a 'fuzzy ball of light', consistent with his earlier prediction.

The Unexplained Mass Anomaly of 3I/ATLAS

Despite NASA's focus on the object's typical characteristics, Professor Loeb was quick to point out that key anomalies were conspicuously absent from the discussion. He highlighted that NASA representatives did not address the 12 unusual aspects of 3I/ATLAS, most notably its comparatively large mass and the alignment of its trajectory with the plane of the planets. Loeb cited his prior work, explaining that the comet's mass is a million times larger than that of 1I/'Oumuamua and a thousand times larger than that of 2I/Borisov, highlighting its concerning 'mass anomaly'.

These 12 'puzzles' form the core of his scepticism. Beyond the anomalous mass and orbit, Loeb's list includes its extreme negative polarisation (unprecedented for known comets), its gas plume containing only 4% water by mass (unlike familiar solar system comets), and its gas plume showing a high concentration of nickel and iron—a composition more consistent with industrially produced metal alloys. He also notes its non-gravitational acceleration near perihelion, which, if purely natural, would require massive evaporation without any evidence of the object fragmenting.

Adding further intrigue, recent observations captured by amateur astronomers after 3I/ATLAS's closest approach to the Sun on Oct. 29, 2025, showed tightly collimated jets extending approximately a million kilometres. Loeb highlighted this crucial data, stating, 'These images show tightly collimated jets pointing towards and away from the Sun and reaching distances of order a million kilometres'.

The jets composition, speed and mass loading rate are now the focus of upcoming observations from larger ground-based telescopes, alongside Hubble and Webb instruments. These measurements aim to determine whether the jets are produced by natural sublimation or 'other processes'.

The Hunt for Fragments and Future Measurements of 3I/ATLAS

The object's closest approach to Earth on Dec. 19, 2025, is expected to provide critical additional data. As Loeb noted, 'We should know the answer by the time 3I/ATLAS is 'closest to Earth' on that date'. He remains committed to a deep dive into the available information, stating, 'In the coming days I will analyse this data quantitatively to extract the most important information out of it'.

Furthermore, Loeb suggested monitoring for fragments or accompanying objects associated with 3I/ATLAS. He recommended that NASA and associated observatories closely examine data from Mars rovers, orbiters and Galileo Project instruments for potential secondary objects. The motive for this scrutiny is profound, as Loeb suggested, 'Related data from Mars rovers or orbiters or from Earth-based NASA satellites or Galileo Project observatories could reveal fragments from an iceberg that broke up or mini-probes released by a technological mothership'.

The final verdict on 3I/ATLAS remains highly contested. While NASA maintains the status quo, categorising the interstellar object as a natural comet, the serious anomalies — from its colossal mass to the peculiar metallic composition of its jets — demand far greater scrutiny. The next critical data point is the object's closest approach to Earth on Dec. 19, 2025. It is imperative that the astronomical community, including amateur observers and research institutions, continues to monitor all available data, especially for any potential fragments or secondary objects.