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3h ago

3I/ATLAS Surges in Brightness Near the Sun as New Data Point to Cosmic‑Ray–Processed Crust

Fresh JWST and SPHEREx spectra indicate a galactic‑cosmic‑ray–processed outer layer on the interstellar visitor, prompting targeted post‑perihelion checks.

Image
an image of a comet streaking through space with the stars around it reflecting rainbows
Image of comet 3I/ATLAS captured by the Gemini Multi-Object Spectrograph on Gemini South at Cerro Pachón in Chile (Credit : International Gemini Observatory/NOIRLab/NSF/AURA)
(Image Credit: NASA/Intl. Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist)

Overview

  • Space-based solar observatories STEREO, SOHO and GOES‑19 recorded an unusually steep pre‑perihelion brightening (≈ r^-7.5) and a visible shift to bluer color around Oct. 29–30.
  • JWST/NIRSpec and SPHEREx measured extreme volatiles in the coma, with CO2/H2O ≈ 7.6±0.3 and CO/H2O ≈ 1.65±0.09, far outside typical solar‑system comet trends.
  • An arXiv analysis interprets the spectra and red continuum slopes as evidence of galactic cosmic‑ray alteration, estimating an irradiated crust roughly 15–20 meters deep that current outgassing samples.
  • Most planetary scientists and NASA officials describe the object as a natural, CO2‑driven comet, while Avi Loeb promotes artificial‑origin and “non‑gravitational acceleration” claims that others say are unsubstantiated by the available data.
  • Ground follow‑up is constrained by solar conjunction until mid‑ to late‑November, with planned observations expected to probe whether deeper, less‑processed material becomes exposed and to refine any non‑gravitational terms.