How much water did 3I/ATLAS release at its peak after perihelion?
Two answers, none aheadNone is ahead yet. See what would settle it.
Where it stands
Two answers have been proposed. None is ahead on the evidence yet. Two are still possible.
Why it matters
Two analyses of the same SOHO/SWAN hydrogen data differ eightfold (3.2 × 10^29 against about 4 × 10^28 molecules a second), and Juice measured 8 × 10^28. The rate sets the mass lost and how much of the surface was active.
Answers 2
The tests
| Measurement · 95% interval10^28 molecules/s | 4 to 8 × 10^28predicts +3 to +10 | about 3 × 10^29predicts +20 to +45 | Weighs |
|---|---|---|---|
| Combi 2025, Water production, SOHO/SWAN, 6 Nov 2025no interval given | — | — | — |
| Tan et al. 2026, Peak water production, SOHO/SWAN 3D modelno interval given | — | — | — |
| Bockelee-Morvan et al. 2026, Water production, Juice MAJIS, 2 Nov 2025no interval given | — | — | — |
| Run both SWAN models on the same framesnot measured yet · a next step | Planned | Planned | — |
| 0 of 3 measurements separate the answers. Each cell is computed from the interval and the answer’s predicted range; a measurement that fits every answer weighs nothing. | |||
Next steps 1
1
Run both SWAN models on the same frames
Could decidePoor odds~60 h
2score
Details
Apply the Combi and Tan hydrogen-coma models to the same SOHO/SWAN images for 6 November 2025. Agreement near 4 × 10^28 rules out the high value; agreement near 3 × 10^29 rules out the low one. Needs the SWAN team's processed frames.
Ranked by how likely each is to move the key question, for the time it takes
History
- Combi: SWAN standard model: 3.17 × 10^29 on 6 NovemberFor: About 3 × 10^29 molecules a second
- Bockelee-Morvan et al.: juice measured 8 falling to 4 × 10^28 a secondFor: Four to eight times 10^28 molecules a second
- ESA: juice measured 8 falling to 4 × 10^28 a secondFor: Four to eight times 10^28 molecules a second
- Tan et al.: a 3D model of the SWAN data peaks near 4 × 10^28For: Four to eight times 10^28 molecules a second
- Session 1: raised the question, proposed two answers and found three results bearing on its answers