3I/ATLAS, the third discovered interstellar object, has a heliocentric speed of 58 km/s and exhibits cometary activity.
Comet
Posted inAstronomy & Telescopes, Comets and Asteroids, Interstellar, Status Report
Near-Discovery SOAR Photometry of the Third Interstellar Object: 3I/ATLAS
3I/ATLAS was discovered on UT 2025 July 1 and joins a limited but growing population of detected ∼102−103 m scale interstellar objects.
Posted inAstrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report
Onset of CN Emission in 3I/ATLAS: Evidence for Strong Carbon-Chain Depletion
Interstellar objects provide a direct window into the environmental conditions around stars other than the Sun.
Posted inAstrochemistry, Astrogeology, Comets and Asteroids, Icy Worlds, Interstellar, Missions & Hardware, Press Release
SwRI-proposed Mission Could Encounter And Explore A Future Interstellar Comet Like3I/ATLAS Up Close
Southwest Research Institute (SwRI) has completed a mission study detailing how a proposed spacecraft could fly by an interstellar comet, providing remarkable insights into the properties of bodies originating beyond […]
Posted inAstrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Comets and Asteroids, Habitable Zones, Icy Worlds, Impact events, Status Report, Water/Hycean Worlds & Oceanography
Isotopic Composition Of Cometary Water And The Origin Of Earth’s Oceans
Studies of the water content and isotopic composition of water-rich asteroids and comets are of key interest for understanding the late accretion stage of the Solar System cometary and chondritic […]
![CN production versus heliocentric distance: Blue circles show VLT/X-shooter measurements of 3I/ATLAS (this work); the black solid and gray dashed curves are power–law fits to the 3I data only, giving Q(CN) ∝ r −9.38±1.2 h (weighted) and Q(CN) ∝ r −9.14±1.57 h (unweighted), respectively. Colored symbols compare with Solar–system comets compiled from the literature, grouped by dynamical class as in the legend; green squares mark measurements for 2I/Borisov. The left axis gives log10[Q(CN)/atoms s−1 ] and the bottom axis in log-scale the heliocentric distance rh (au). The right axis shows an approximate equilibrium surface temperature T(rh). Horizontal dashed lines indicate sublimation thresholds for CO, NH3, CO2, and H2O. Other comets references: Manfroid et al. (2021), Opitom et al. (2016), Opitom et al. (2017), Opitom et al. (2019), Fitzsimmons et al. (2019), Rauer et al. (2003) and S -- astro-ph.SR](https://i0.wp.com/astrobiology.com/wp-content/uploads/2025/08/VLT-Observations-Of-Interstellar.png?resize=1200%2C785&ssl=1)
Posted inAstrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Status Report
VLT Observations Of Interstellar Comet 3I/ATLAS II. From quiescence To Glow: Dramatic Rise Of Ni I Emission And Incipient CN Outgassing At Large Heliocentric Distances
We report VLT spectroscopy of the interstellar comet 3I/ATLAS (C/2025 N1) from rh≃4.4 to 2.85 au using X-shooter (300-550 nm, R≃3000) and UVES (optical, R≃35k−80k).
Posted inAstrochemistry, Astrogeology, Astronomy & Telescopes, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report
JWST Detection Of A Carbon Dioxide Dominated Gas Coma Surrounding Interstellar Object 3I/ATLAS
3I/ATLAS is the third confirmed interstellar object to visit our Solar System, and only the second to display a clear coma.
Posted inAstrochemistry, Astrogeology, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Planetary Protection & Biosafety, Press Release, Sample Return
NASA’s Bennu Samples Reveal Complex Origins, Dramatic Transformation
Asteroid Bennu, sampled by NASA’s OSIRIS-REx mission in 2020, is a mixture of dust that formed in our solar system, organic matter from interstellar space, and pre-solar system stardust. Its […]
Posted inAstrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Status Report
SPHEREx Discovery of Strong Water Ice Absorption and an Extended Carbon Dioxide Coma in 3I/ATLAS
In mid-August 2025, 0.75-5.0 micron SPHEREx imaging spectrophotometric and ancillary NASA-IRTF SpeX 0.7-2.5 micron low-resolution spectral observations of Interstellar Object 3I ATLAS were obtained.
Posted inAstronomy & Telescopes, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Press Release
Update: Hubble Space Telescope Observations of the Interstellar Interloper 3I/ATLAS
We present high angular resolution observations of the third known interstellar interloper, 3I/ATLAS, from the Hubble Space Telescope.