Robotic telescopes on Projeto Telescópio Virtual captured recent images of the interstellar comet 3I/ATLAS, revealing a longer, more defined and brighter ion tail than in previous observations. The object, detected for the first time on July 1, 2025 by the ATLAS system in Chile, crosses Sistema Solar on a hyperbolic trajectory. Essa evolution occurs as the comet moves away from perihelion, reached on October 29, 2025, 1.4 astronomical units from Sol.
Astronomers monitor the phenomenon to analyze the chemical composition of the comet, which carries materials from another star system. The greater visibility of the tail allows studies on the interaction with solar winds. 3I/ATLAS represents the third confirmed interstellar visitor, following 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.
The initial discovery occurred at Río Hurtado, at Chile, using automated telescopes designed for impact warning. Preliminary Observações confirmed cometary activity, with a reddish coma indicative of dust.
Trajectory and speed of the cosmic visitor
Comet 3I/ATLAS follows an orbit inclined to the ecliptic, with an initial speed of around 61 km/s. Essa dynamics differentiate it from local comets, which orbit Sol in an elliptical fashion.
On October 3, 2025, it passed within 28 million kilometers of Marte, allowing observations from probes like Mars Reconnaissance Orbiter. The maximum proximity to Terra occurred in December 2025, at 270 million kilometers, without risk of collision.
Data from Telescópio Espacial Hubble, captured in July 2025, showed a faint tail pointing east, formed by dust pushed by solar radiation. Estudos indicate that the core, estimated to be between 3 and 11 km in diameter, releases gases in a stable manner.
The hyperbolic trajectory confirms its external origin, with an age estimated at 7 to 14 billion years, greater than that of Sistema Solar.
Chemical composition revealed by recent analyzes
Telescópio Espacial James Webb identified carbon dioxide, carbon monoxide, carbonyl sulfide and water ice in the comet. Esses compounds suggest formation in an ancient region of Via Láctea.
- Carbon dioxide dominates the coma, indicating early release by solar heating.
- Carbon monoxide and water point to thick galactic disk origins.
- Reddish poetry, similar to 2I/Borisov, reflects evolving composition.
- Cyanide and nickel in notable quantities, common in comets but rare in proportions.
These elements provide clues about distant planetary systems. Observações of August 2025 recorded an increase in the redness of the coma, linked to increasing activity.
The presence of volatile compounds reinforces hypotheses about ejection from another stellar system billions of years ago.
Space mission observations in October
Probes such as Europa Clipper and Hera crossed paths close to the comet’s tail between October 30 and November 6, 2025.
The Psyche mission captured images in September 2025, from 53 million kilometers, revealing dust grains and jets of material. ExoMars Trace Gas Orbiter refined the trajectory using data from Marte in October.
Instruments like HiRISE recorded the dust-shrouded icy core on October 2. ESA’s Juice mission plans analyzes in November 2025 with spectrometers and particle sensors.
These contributions multiply study perspectives, from ultraviolet to infrared.
Hubble contributions to visual details
Hubble provided detailed images on July 21, 2025, showing a teardrop-shaped core with a dust coma. The exposure revealed slow rotation and side jets transformed into a tail.
Data from September indicated hotspots on the surface releasing material. The TESS mission detected activity in May 2025, two months before the official discovery.
These observations confirm flare-free stability, contrasting with more volatile solar comets.
Importance for planetary formation studies
Comet 3I/ATLAS offers intact samples of another system, with a composition rich in water and carbon. Astrônomos estimate that it traveled for billions of years, mixing with neighboring stars.
Observations from the Lucy mission in September 2025 highlighted fine dust in the coma. Vera C. Rubin, in Chile, speeds up future detections of similar visitors.
- Initial studies date back to June 14, 2025, via ATLAS files.
- Activity confirmed on July 2 by telescopes at Chile and Havaí.
- Expanded ion tail observed in November, with brightness above magnitude 12.
These data enrich models of galactic evolution.
Current visibility and continuous monitoring
The comet remains observable with amateur telescopes until spring 2026, in constellations such as Virgem and Leão. Sua luminosity gradually decreases after perihelion.
The Rede Internacional of Alerta of Asteroides coordinates global tracking. By December 2025, it reaches 1.8 AU of Terra, facilitating long-term studies.
Astronomers predict exit to interstellar space in 2026, heading to the constellation of Gêmeos.
