NASA’s SPHEREx telescope detects key organic molecules in interstellar comet 3I/ATLAS

The Nasa space observatory SPHEREx captured unprecedented data from the interstellar comet 3I/ATLAS between December 8 and 15, 2025, revealing the release of organic molecules during its exit from Sistema Solar. The object, discovered on July 1, 2025 by the ATLAS system in Chile, had already passed perihelion at the end of October of that year. Observations indicate that solar heating activated processes that expelled compounds such as methanol, methane and cyanide, considered chemical building blocks for prebiotic reactions. Cientistas highlight that this detection expands the understanding of the distribution of organic matter in the cosmos.

Comet 3I/ATLAS has become the third confirmed interstellar object visiting our planetary system, after ‘Oumuamua and Borisov. Sua origin in another star system allows us to analyze primordial materials preserved for billions of years. SPHEREx, designed to map the sky in 102-wavelength infrared, recorded emissions of dust, water vapor, carbon dioxide and organic molecules in the comet’s coma.

Intense post-perihelion activity

The comet showed a significant increase in brightness two months after the closest point to Sol. Essa change reflects the sublimation of underground ice mixed with rock and organic material. Gaseous emissions have become more diverse compared to previous observations in August 2025.

Spectral data show coma rich in carbon dioxide, with smaller contributions from carbon monoxide and water. The presence of cyanide and organic compounds with C-H bonds suggests the release of species trapped in water ice phases.

Chemical composition revealed

SPHEREx identified specific emission lines for methanol, methane and cyanide in the infrared region. Essas molecules arise from non-biological processes in cold interstellar environments. The coma exhibited asymmetric morphology in some components, aligned with the solar direction.

Refractory dust contributed to the observed light scattering. Emissões of gaseous water increased drastically, indicating activation of internal reservoirs by solar heat.

Coma and emissions details

• CN (cyanide) emissions at 0.93 μm, associated with dust.
• Organic C-H lines between 3.2 and 3.6 μm.
• CO₂ at 4.25-4.27 μm, with extended coma.
• CO at 4.6-4.8 μm, symmetric to the nucleus.
• H₂O at 2.7 μm, with a 40-fold increase compared to previous phases.

These data help compare 3I/ATLAS with solar comets, highlighting differences in the proportion of volatiles.

Additional observations

Other Nasa missions have followed the comet since its discovery. Imagens of Hubble captured the object in July 2025 277 million miles from Terra. Additional Dados show comas rich in gas and dust, with winds releasing ancient debris.

The trajectory took the comet to pass at safe distances from Terra, without risk of impact. SPHEREx provided detailed spectroscopy, revealing reactions of pristine ices to solar heating.

Importance to astrochemistry

The detection reinforces that complex organic molecules exist in objects formed in other stellar systems. Esses compounds participate in chemical processes that precede biology under appropriate conditions. Estudos from 3I/ATLAS offers window into distant primordial chemistry.

The comet continues its journey outward from Sistema Solar, with activity decreasing as it moves away from Sol. Observações Futures may refine models of interstellar origins.

Unique core composition

Analysis indicates a mixture of water ice and carbon dioxide with organic materials. The initial absence of certain gaseous emissions in August evolved into intense release in December. Essa transition demonstrates how interstellar objects respond to the solar environment.

The nucleus probably preserves the composition of its original formation. Diferenças in relation to local comets suggests regional variations in the galaxy.