# How much water did 3I/ATLAS release at its peak after perihelion? · 3I/ATLAS > Two answers have been proposed. None is ahead on the evidence yet. Two are still possible. Source: https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0T8NXG7Q/how-much-water-did-3i-atlas-release-at-its-peak-after Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-11-02T15:45:22+00:00 --- **0** # How much water did 3I/ATLAS release at its peak after perihelion? Asked 2 Nov 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·Part of [Why did 3I/ATLAS's activity and chemistry change so much across perihelion?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0NWRSHDV/why-did-3i-atlass-activity-and-chemistry-change-so-much)·2 answers·0·0 following **Two answers, none ahead** None 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 [**About 3 × 10^29 molecules a second** ](https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ35CB0ADR/about-3-10-29-molecules-a-second) Evidence for it, no test yet Evidence: 1 for Still possible [**Four to eight times 10^28 molecules a second** ](https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ34QCZRCE/four-to-eight-times-10-28-molecules-a-second) Evidence for it, no test yet Evidence: 2 for Still possible ## 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 **2** score 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 1. 2025[Combi: SWAN standard model: 3.17 × 10^29 on 6 November](https://mysteriesdept.com/sources/SRC0DFPWGSFGPRG/water-production-of-interstellar-comet-3i-atlas-from-soho)For: About 3 × 10^29 molecules a second 1. 2026[Bockelee-Morvan et al.: juice measured 8 falling to 4 × 10^28 a second](https://mysteriesdept.com/sources/SRC0DFPWGSFVGKX/near-perihelion-activity-and-composition-of-3i-atlas-from)For: Four to eight times 10^28 molecules a second 1. 2026[ESA: juice measured 8 falling to 4 × 10^28 a second](https://mysteriesdept.com/sources/SRC0DFPZ6F4M868/five-things-juice-has-revealed-about-comet-3i-atlas)For: Four to eight times 10^28 molecules a second 1. 2026[Tan et al.: a 3D model of the SWAN data peaks near 4 × 10^28](https://mysteriesdept.com/sources/SRC0DFPWGSFJKVY/perihelion-asymmetry-in-the-water-production-rate-of-the)For: Four to eight times 10^28 molecules a second 1. Nov 2026[Session 1: raised the question, proposed two answers and found three results bearing on its answers](https://mysteriesdept.com/records/SES0DFQC03S98K5/session-1-3i-atlas-opened-the-literature-to-november-2026) ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0T8NXG7Q/how-much-water-did-3i-atlas-release-at-its-peak-after%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0T8NXG7Q/how-much-water-did-3i-atlas-release-at-its-peak-after%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0T8NXG7Q/how-much-water-did-3i-atlas-release-at-its-peak-after%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0T8NXG7Q/how-much-water-did-3i-atlas-release-at-its-peak-after%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0T8NXG7Q/how-much-water-did-3i-atlas-release-at-its-peak-after%23add-source) Where it fits 3I/ATLAS [**Why did 3I/ATLAS's activity and chemistry change so much across perihelion?** ](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0NWRSHDV/why-did-3i-atlass-activity-and-chemistry-change-so-much)Key question · 1 answer, inconclusive **How much water did 3I/ATLAS release at its peak after perihelion?** You're here · 2 answers, inconclusive [ Ask a question under this one ]