Comets and Asteroids

Prospects For The Crossing Of Comet 3I/ATLAS’s Ion Tail

By Keith Cowing
Status Report
astro-ph.EP
October 21, 2025
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Prospects For The Crossing Of Comet 3I/ATLAS’s Ion Tail
Simulation of 3I/ATLAS’s ion tail on 1 November 2025 assuming a 460 kms−1 radial flow. Positions of Europa Clipper, Sun, Hera, and 3I/ATLAS are shown in a frame where the Sun-Europa Clipper line is fixed. The plane represents that of the ecliptic, with grid lines spaced at 0.1 au. The comet’s position is shown every 6 hours, with legs showing its position north of the ecliptic. Europa Clipper is also north of the ecliptic by 0.069 au. Earth and Mars’s mean orbital distances are included for scale. — astro-ph.EP

During October – November 2025, interstellar comet 3I/ATLAS, will pass upstream of the Europa Clipper and Hera spacecraft.

Here, we identify two potential opportunities for in-situ observations of 3I’s ion tail by immersion, facilitated by the close alignment between the comet’s hyperbolic trajectory with the ecliptic plane. During the period 30 October – 6 November 2025, it is predicted that Europa Clipper will potentially be immersed within the ion tail of 3I/ATLAS, providing the opportunity to detect the signatures of an interstellar comet’s ion tail.

Characteristic changes to the solar wind are also expected to be observed; a magnetic draping structure associated with the comet may be identifiable. It is further predicted that spacecraft Hera will possibly be immersed within the ion tail of 3I/ATLAS during the period 25 October – 1 November 2025.

Comments: Will be published in RNAAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2510.13222 [astro-ph.EP] (or arXiv:2510.13222v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2510.13222
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Related DOI:
https://doi.org/10.3847/2515-5172/ae12e6
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Submission history
From: Samuel Grant
[v1] Wed, 15 Oct 2025 07:20:10 UTC (1,390 KB)
https://arxiv.org/abs/2510.13222

Astrobiology, Astronomy, interstellar,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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