3i-ATLAS anomalies

A) 3i-ATLAS:  “18 anomalies” (as published), in chronological order. This is the reported and argued list, not NASA consensus.

Early orbit and geometry, known soon after discovery in early July 2025.

1. Trajectory nearly aligned with the ecliptic within about 5 degrees, framed as unlikely.
2. Arrival timing described as “fine-tuned,” including close passes to Mars and Jupiter and being poorly observable from Earth at perihelion.
3. Forecast March 16, 2026 perijove approximately equal to Jupiter’s Hill radius, framed as a rare coincidence.
4. Arrival direction near the “Wow!” signal direction within about 9 degrees, framed as unlikely.

Pre-perihelion imaging and rotation, July to August 2025.

5. Hubble July 21, 2025 image interpreted as a long, collimated sunward jet, claimed unlike known comets.
6. Initial rotation axis aligned near the sunward direction on entry, claimed to have low probability.
7. Observed wobble of the pre-perihelion sunward jet implying the jet base is very near the sun-facing pole, claimed low probability.

Composition and polarimetry, August to September 2025.

8. SPHEREx observations interpreted as icy fragments pre-perihelion, then a change post-perihelion.
9. Extreme negative polarization reported as unprecedented among comets.
10. Nickel to iron and nickel to cyanide abundance framed as “industrial-like.”

Perihelion behavior, September to October 2025, with perihelion around October 29 to 30.

11. Rapid brightening near perihelion with a very steep brightening law.
12. “Bluer than the Sun” appearance near perihelion, attributed to gas emission and framed as unusual.
13. Non-gravitational acceleration near perihelion framed as too large for a normal comet unless extreme mass loss occurred, interpreted by some as a possible “engine.”
14. Gravitational deflection at perihelion of about 16 degrees equals two times a claimed jet opening angle, presented as a coincidence.

Post-perihelion, December 2025 to January 2026.

15. SPHEREx reports of post-perihelion organics and much higher water production, framed as hard to reconcile with long interstellar exposure without deep burial.
16. Sunward anti-tail or jet appears both before and after perihelion despite reversal relative to motion, framed as extremely unlikely.
17. Anti-tail described as penetrating solar wind and radiation for huge distances, with particle size and mass arguments framed as problematic.
18. Hubble January 14, 2026 observations showing three symmetric “mini-jets” spaced about 120 degrees apart, framed as a possible technosignature.

B) A science-grounded list of what is actually observed and how it is usually explained.

1. Interstellar hyperbolic orbit and trajectory predictions, which are normal for an interstellar visitor.
2. Cometary activity such as coma and dust seen by Hubble early on, including a teardrop dust cocoon.
3. Rapid brightening near perihelion and blue color consistent with strong activity and gas emission in solar-imager photometry.
4. Non-gravitational acceleration commonly modeled as outgassing and mass loss, with papers estimating the required mass loss.
5. Unusual polarization signature documented in a peer-review preprint as unprecedented among comets and asteroids observed so far.
6. Nickel and iron behavior in the coma studied in the literature, including evolution of the nickel to iron ratio before perihelion.
7. Close Mars imaging campaign in which HiRISE and MRO imaged the object and its morphology and extent were discussed in releases.
8. Organics and water production changes after perihelion reported from space-based observations and generally interpreted as changing activity as solar heating increases and different volatiles dominate.

Key takeaway. The “18 anomalies” number corresponds to a particular author’s enumerated list. NASA and most comet scientists treat the object as a natural comet with some unusual but physically explainable properties, especially given outgassing, viewing geometry, and the very small sample size of known interstellar visitors.