Lead: On 8 November 2025 at 04:10 UT, observers reported a complex, multi‑jet pattern emerging from interstellar object 3I/ATLAS shortly after perihelion. Stacked RGB images taken at 29° solar elongation show a glowing halo stretching roughly 500,000 km (about 5 arcminutes) and at least seven discrete jets, some appearing as sunward anti‑tails. Observations were made under bright moonlight and ended as twilight encroached; the origin of the jets—natural outgassing from volatile deposits or engineered thrusters—remains unresolved.
Key Takeaways
- Observation timestamp: 04:10 UT on 8 November 2025, at 29° separation from the Sun in the sky.
- Image dataset: 24 exposures in green (each 35 seconds), plus 2 red and 2 blue frames stacked to produce the composite.
- Large halo: luminous material detected out to ~500,000 km (reported as ~5 arcminutes in angular extent).
- Jet count: at least seven distinct jets identified in the stacked frames; several features project sunward and resemble anti‑tails.
- Viewing conditions: 3I/ATLAS was 7–10° above the horizon when imaged; bright moonlight and approaching twilight limited integration time.
- Interpretive gap: current data do not distinguish between localized sublimation on a natural nucleus and directed thrust from a spacecraft‑class object.
Background
Interstellar visitors are rare: 1I/ʻOumuamua (2017) and 2I/Borisov (2019) remain the most studied examples, showing very different observational signatures. ʻOumuamua displayed an asteroidal appearance with non‑gravitational acceleration debated in origin; Borisov showed cometary gas and dust consistent with volatile sublimation. The identification of 3I/ATLAS as an interstellar object places it in that sparse category and raises immediate interest in morphology and activity near perihelion.
Cometary jets in Solar System comets typically arise from small, active patches of exposed ice on rotating nuclei; their number, direction and persistence depend on rotation, surface heterogeneity and illumination angle. Conversely, a spacecraft utilizing reaction jets for attitude or trajectory control can produce collimated, repetitive plumes whose geometry may mimic natural jets in some images. Disentangling these scenarios requires spectroscopy, longer temporal baselines and observations at different phase angles.
Main Event
Observers M. Jäger, G. Rhemann and E. Prosperi acquired a composite image set at 04:10 UT on 8 November 2025 while 3I/ATLAS lay 29° from the Sun. The final stacked RGB frame combined twenty‑four 35‑second green exposures plus two red and two blue frames to increase signal‑to‑noise. The resulting image shows an extensive diffuse halo and a structured jet system with at least seven components, some projecting toward the Sun (anti‑tails) rather than away.
During the imaging run 3I/ATLAS sat low on the horizon—roughly 7–10°—which accentuates atmospheric extinction and complicates photometric calibration. Observers reported that bright moonlight raised the background and that twilight curtailed further exposures, limiting the temporal coverage to a single sequence. The handful of frames nonetheless reveal persistent features across the stack rather than transient noise spikes, suggesting that the jets are real structures in the near‑comet environment.
Photometric and morphological notes from the dataset include the halo extent (~500,000 km) and the angular scale (~5 arcminutes) used to estimate the linear size at the object’s geocentric distance. The apparent multiplicity of jets and the presence of sunward anti‑tails are notable morphologies that are uncommon for typical long‑period comets at similar heliocentric phases but are not without precedent in projection and viewing geometry.
Analysis & Implications
If the jets originate from localized volatile reservoirs on a natural nucleus, their multiplicity implies a heterogeneous surface with several active vents. Multiple jets can also result from rotation exposing different active areas as sunlight sweeps across the surface; without a rotation period and time‑resolved imaging, constraining that scenario is difficult. Gas species identification (e.g., CN, C2, CO) via spectroscopy would help confirm sublimation processes and estimate mass‑loss rates.
Alternatively, if the features are produced by engineered propulsion or attitude control thrusters, one would expect repetitive, collimated plumes fixed in spacecraft coordinates and possible correlations with non‑gravitational acceleration vectors in astrometry. Demonstrating an artificial origin would require consistent thrust signatures, telemetry‑like periodicity, or independent corroborating evidence beyond morphology alone. Current images do not provide that level of diagnostic detail.
Either interpretation has implications: a cometary origin adds to the diversity of volatile content observed in interstellar bodies and informs models of small‑body formation in other systems. An artificial origin would have profound consequences for search strategies and follow‑up priorities, but extraordinary claims demand extraordinary evidence — including multiple observing platforms, spectroscopy, and sustained astrometric monitoring.
Comparison & Data
| Object | Key discovery/observation | Notable morphology |
|---|---|---|
| 1I/ʻOumuamua (2017) | Interstellar trajectory; non‑gravitational acceleration | Pointlike, no clear coma |
| 2I/Borisov (2019) | Interstellar comet; spectroscopic gas detections | Coma and classical dust tail |
| 3I/ATLAS (2025) | Observed 08 Nov 2025, 04:10 UT; stacked RGB images | ~500,000 km halo; ≥7 jets, some sunward |
The table places 3I/ATLAS in context: unlike ʻOumuamua, which lacked a clear coma, and unlike Borisov, where gas production was spectroscopically confirmed, 3I/ATLAS shows complex morphology but lacks publicly released spectral diagnostics at the time of reporting. The halo size and multi‑jet appearance are quantitatively distinct from the earlier interstellar visitors.
Reactions & Quotes
Paraphrasing the imaging team: the stacked frames consistently show multiple narrow features and an extensive halo reaching roughly 500,000 km, visible despite bright moonlight.
M. Jäger, G. Rhemann & E. Prosperi (observers)
Paraphrasing the report author: current imagery does not settle whether the jets are natural outgassing or propulsion‑related; additional spectroscopy and astrometry are required.
Avi Loeb (Galileo Project)
Paraphrasing an unaffiliated comet researcher: multiple active vents can produce similar structures, but sunward anti‑tails and the object’s geometry mean projection effects must be carefully modeled.
Unaffiliated comet researcher (independent expert)
Unconfirmed
- Whether the jets are produced by natural sublimation from surface ice pockets rather than engineered thrusters remains unproven.
- Spectral composition of the halo (specific gas species and dust‑to‑gas ratio) has not been publicly released and is therefore unconfirmed.
- Any claim of non‑gravitational acceleration correlated with the jet directions lacks corroborating astrometric analysis at this stage.
Bottom Line
The stacked images taken on 8 November 2025 provide compelling evidence of complex activity around 3I/ATLAS: a large halo and at least seven jets are visible in the dataset, but the observations alone do not uniquely determine the mechanism. Natural cometary activity—localized sublimation on a heterogeneous nucleus—remains a plausible explanation and aligns with known comet physics, yet the morphology leaves room for alternative interpretations.
Resolving the origin requires rapid, coordinated follow‑up: high‑resolution imaging at different phase angles, spectroscopy to identify gas species, and precise astrometry to detect any sustained non‑gravitational accelerations. Until that body of evidence is available, the safest scientific posture is agnostic: note the striking morphology, quantify it, and prioritize multi‑wavelength and time‑series observations to move from intriguing morphology to tested hypothesis.
Sources
- A. Loeb, “A Complex Jet Structure Emanates from 3I/ATLAS After Perihelion,” Medium — author blog / report summarizing the observing team
- Galileo Project — organization (research program associated with the report author)