Harvard astrophysicist urges caution as interstellar object 3I/ATLAS draws scrutiny

Overview of 3I/ATLAS

First detected in July, the object designated 3I/ATLAS is estimated to be several kilometres across and unusually massive for an interstellar visitor. Observations indicate a diameter on the order of 5.6 kilometres and a mass estimated in the billions of tonnes. Its velocity is notably higher than previously observed interstellar objects.

Physical and dynamical properties

Photometric monitoring and modelling show fluctuating brightness consistent with tumbling or an irregular shape, and surface composition appears to vary across the object. Its incoming trajectory lies close to the plane of the planets, within a few degrees of the ecliptic, an alignment that researchers describe as atypical for known interstellar interlopers.

Chemical findings and interpretation

Spectroscopic observations from ground-based facilities reported emission lines attributed to nickel tetracarbonyl and an absence of detectable iron. The reported chemical signature, including a measured nickel release on the order of grams per second, has prompted debate because nickel tetracarbonyl on Earth is associated with industrial processes. Some scientists urge caution pending independent confirmation and further measurements.

Claims of possible artificial origin

Professor Avi Loeb, a Harvard astrophysicist known for advocating consideration of non‑standard explanations for unusual astronomical phenomena, has suggested 3I/ATLAS might be artificial. He has pointed to the object's chemical emissions, its motion, and an apparent sunward-directed gas jet as reasons to entertain that possibility. Loeb also called for prompt release of all relevant observational data and highlighted a target date of October 29 for further observations and analysis.

Responses from other researchers and agencies

NASA and other institutions have emphasised that 3I/ATLAS poses no threat to Earth and that additional observations are underway. Some astronomers have cautioned against early conclusions and stressed the need for peer-reviewed analyses and independent verification of spectral identifications.

Natural-origin models

A team of astronomers produced dynamical simulations exploring potential stellar encounters and origin scenarios. Their preliminary results, submitted for peer review, found multiple candidate stellar passages but no clear stellar interaction that would require an artificial cause. The authors suggest the object could have formed in the Galaxy’s thin disk billions of years ago and later been ejected into an interstellar trajectory.

Scientific debate and next steps

The case of 3I/ATLAS illustrates tensions in interpreting limited, early data on rare interstellar objects. Some researchers argue the observed anomalies merit exploration of unconventional explanations; others stress that surprising signatures can often be reconciled with natural processes once more data are obtained.

Planned follow-up observations, including spectroscopy and imaging from multiple facilities, aim to clarify the object’s composition, rotation state, and trajectory. The community expects that additional measurements released after the October observations will be critical to resolving competing hypotheses.

What to expect

• Further spectroscopic confirmation of chemical species and abundances.
• High-cadence photometry to refine rotation and tumbling models.
• Continued dynamical studies to search for plausible ejection scenarios and stellar encounters.

Until independent analyses are completed and data are shared broadly, the origin of 3I/ATLAS will remain uncertain and the scientific community will continue to evaluate both natural and unconventional explanations.