Robotic telescopes on Projeto Telescópio Virtual have captured new images of the interstellar comet 3I/ATLAS, revealing a longer, sharper and brighter ion tail than in previous observations. The object, first detected on July 1, 2025 by the ATLAS system at Chile, crosses Sistema Solar on a hyperbolic trajectory. The evolution of Essa occurs as the comet moves away from perihelion, reached on October 29, 2025 at 1.4 astronomical units from Sol.
Astronomers are following the phenomenon to analyze the chemical composition of the comet, which transports 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, after 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.
The initial discovery occurred at Río Hurtado, at Chile, using automated telescopes designed to warn of impacts. Preliminary Observações confirmed the comet’s activity, with a reddish mane 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. The dynamics of Essa differentiate it from local comets, which orbit Sol elliptically.
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 nucleus, whose diameter is estimated to be between 3 and 11 km, releases gases in a stable manner.
The hyperbolic trajectory confirms its external origin, with an estimated age of between 7 and 14 billion years, older than that of Sistema Solar.
Chemical composition revealed by recent analyses.
Telescope Espacial James Webb identified carbon dioxide, carbon monoxide, carbonyl sulfide and water ice in the comet. The compounds Esses 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 the origin of a thick galactic disk.
- The reddish poetry, similar to 2I/Borisov, reflects an evolving composition.
- Cyanide and nickel in notable quantities, common in comets, but rare in proportions.
These elements provide clues to distant planetary systems. Observações August 2025 recorded an increase in the redness of the coma, related to increased activity.
The presence of volatile compounds reinforces hypotheses about the ejection of another stellar system billions of years ago.
Space mission observations in October
Probes such as Europa Clipper and Hera passed 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-covered icy core on October 2. ESA’s Juice mission plans to carry out 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 nucleus with a dust coma. The exposure exposed a slow rotation and side jets transformed into a tail.
Data from September indicated critical points 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, in contrast to more volatile solar comets.
Importance for planetary formation studies.
The Cometa 3I/ATLAS offers intact samples from another system, with a composition rich in water and carbon. Estima-case Astrônomos has traveled for billions of years, mixing-case 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.
- The initial studies date back to June 14, 2025, through ATLAS files.
- Activity confirmed on July 2 by the Chile and Havaí telescopes.
- Expanded ion tail observed in November, brighter than magnitude 12.
These data enrich models of galactic evolution.
Current visibility and continuous monitoring.
The comet will remain observable with amateur telescopes until spring 2026, in constellations such as Virgem and Leão. The luminosity of Sua gradually decreases after perihelion.
The Rede Internacional of Alerta of Asteroides coordinates global tracking. Até December 2025, will reach 1.8 AU of Terra, facilitating long-term studies.
Astronomers predict departure into interstellar space in 2026, towards the constellation Gêmeos.
