NASA, in collaboration with Agência Espacial Europeia (ESA), is closely monitoring the interstellar comet 3I/ATLAS, the third object of extrasolar origin ever identified in Sistema Solar. Este celestial body was detected on July 1, 2025 by the ATLAS telescope, located at Chile, marking a crucial point for astronomical research.
The trajectory of 3I/ATLAS is characterized by a hyperbolic orbit with an eccentricity greater than 5, a fact that unequivocally confirms its origin outside our stellar system. Sua maximum approach to Sol, known as perihelion, is scheduled for October 29, 2025.
At this point, the comet will be 1.36 astronomical units from Sol, the equivalent of around 203 million kilometers, positioning itself between the orbits of Terra and Marte. Essa proximity represents a significant challenge, as it exposes the cometary nucleus to intense solar radiation.
The trajectory and risk of fragmentation
Intense solar radiation can cause the evaporation of volatile compounds and, consequently, the fragmentation of the comet, a phenomenon already observed with comet 2I/Borisov in 2020. Recent Imagens, obtained between July and September 2025 by Nordic Optical Telescope, reveal jets of dust and ice directed towards Sol, indicating the increasing activity of 3I/ATLAS.
The comet’s high speed, estimated at 245,000 km/h, is a determining factor that corroborates its hyperbolic trajectory, confirming its interstellar nature. Este data is crucial for models predicting its movement and interaction with the solar environment.
Another notable feature is the extreme negative polarization observed, an attribute unprecedented in known comets, which intrigues scientists. Afortunadamente, its ecliptic alignment facilitates monitoring using terrestrial telescopes, allowing continuous and detailed monitoring.
Chemical composition and distant origin
3I/ATLAS spectral analyzes reveal that carbon dioxide is eight times more abundant than water in its composition. The Essa ratio suggests that the comet formed in extremely cold environments, possibly in distant protoplanetary disks, similar to the Cinturão of another star’s Kuiper.
The presence of metals such as nickel, detected by Telescópio Espacial James Webb, further distinguishes 3I/ATLAS from comets that originate in our own solar system. Além Furthermore, the water ice preserved in its core causes unusual scattering of light, offering clues about its formation conditions.
The absence of heavy metals in its composition aligns the comet with characteristics of ancient stars from Via Láctea. In July 2025, images captured by Telescópio Espacial Hubble showed a faint tail, driven by solar radiation, showing the release of volatile materials.
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Challenges in current observation and monitoring
Since October 2025, 3I/ATLAS has been transiting behind Sol, which imposes severe limitations on observations made from Terra. Esta phase makes direct visual monitoring difficult, requiring the use of alternative technologies and strategies to maintain the study of the comet.
Despite the restrictions, the GOES-19 satellite’s CCOR-1 coronagraph managed to capture images of the comet on October 21, 2025, revealing the presence of a coma of gas and dust around its nucleus. Essas observations are vital to understanding the comet’s evolution during its closest passage to Sol.
A Thai amateur astronomer, Starting in November, ground-based telescopes will resume observations, when 3I/ATLAS will become visible at dawn in the constellations of Virgem and Leão, with a magnitude of 11.5.
The comet’s proximity to Marte on October 3, 2025, at a distance of 28 million kilometers, was recorded by ESA’s Trace Gas Orbiter. Essa observation allowed the collection of data on the comet’s interactions with solar plasma, providing valuable information about the interplanetary environment.
The contribution of space missions
NASA’s Europa Clipper probe is scheduled to align with the ion tail of 3I/ATLAS in late October 2025.
On November 4, 2025, ESA’s Juice mission will fly 64 million kilometers from the comet, with the aim of obtaining multispectral data. Essas information is crucial to complement analyzes of the comet’s composition and better understand its origin and evolution.
Lessons from comet Borisov and the future of 3I/ATLAS
Comet 2I/Borisov, another interstellar visitor, suffered fragmentation in March 2020, after its perihelion in December 2019, with its nucleus dividing into two fragments separated by 180 kilometers. Este event was attributed to the evaporation of volatiles and accelerated rotation, releasing large amounts of dust and carbon monoxide into space. The study of Borisov revealed the scattering of organic molecules among stars, suggesting that such comets may originate near red dwarfs. Para o 3I/ATLAS, the telescopes will continue to closely monitor any changes in November 2025, especially with a step within 0.65 astronomical units of Vênus on November 3, looking for signs of instability that could indicate a Borisov-like fate.
Continuous post-perihelion surveillance
In March 2026, comet 3I/ATLAS will cross the orbit of Júpiter, at a distance of 54 million kilometers, providing the Juno probe with the opportunity to record gravitational interactions. Telescópios as well as Canada-France-Hawaii and Vera C. Rubin will begin astrometry of the comet on November 27, 2025, ensuring accurate monitoring of its trajectory and behavior.
