Webb detected methane in interstellar comet 3I/ATLAS
Webb observed 3I/ATLAS twice in December 2025 as the interstellar comet moved away from the Sun, detecting methane directly for the first time in an interstellar object. Its methane-to-water ratio was unusually high, and the comet also released much more carbon dioxide relative to water than typical solar-system comets. Researchers suggested the delayed methane release came from ice beneath the surface warmed during the comet's close solar pass.
The record ends here. Everything below this line is invented.
What if a comet's buried methane changed its predicted path only after it warmed?
Part one
The Late Plume
Every shift, Osei checked the visitor's path before he checked his own pulse. The defense station hung beyond the Moon, where the optical array could keep a new comet in view without Earth in the way. Its projected line crossed no planet, only the station's long-baseline antenna, a structure too expensive to replace before the next visitor came.
The object had been quiet for six weeks. Its light curve and dust halo fit the first trajectory; the station had already scheduled a slow relocation. Then the infrared channel found methane in the wake, concentrated close to the nucleus. The new jet was small, but it had begun after the comet warmed. Osei's models put the changed acceleration inside the margin that made the antenna safe.
His partner had taken the night tug to tow a school telescope away from the station's shadow. If Osei ordered the array moved now, the tug would have to turn back through the same narrow approach corridor. If he waited for another measurement, the comet would reach the antenna before the model settled. The display drew the plume as a thin green line. Then the path bent across the antenna's center.
What’s real
- Webb detected methane in an interstellar comet.
- The observations came after 3I/ATLAS passed the Sun.
- The methane may have been buried below the surface.
What’s invented
- Osei, the defense station, and the antenna are fictional.
- The source did not report a changed trajectory.
- Future comet defense operations are extrapolated.
Part two: The Approach Corridor
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Filed under space, comets, planetary defense, spectroscopy.