The interstellar comet 3I/Atlas, the third object of its nature confirmed to visit our solar system, has surprised the astronomical community. Recent Observações reveals a significant increase in brightness and a pronounced blue hue as it approaches Sol.
This phenomenon, captured by NASA and Agência Espacial Europeia (ESA) satellites, occurs before its closest passage to the star, perihelion, scheduled for October 2025. The intense activity suggests the accelerated release of volatile gases from its icy core.
The unusual combination of brightness and color is providing scientists with crucial data about the composition and origin of objects that formed outside our star system. The detailed study of 3I/Atlas may reveal secrets about planetary formation in other galaxies.
Unraveling light intensity and chemical composition
The intensification of the brightness of comet 3I/Atlas, which manifests itself at a rate twice that of typical comets of Nuvem and Oort, was recorded by instruments such as the Observatório Solar and Heliosférico (SOHO) and the GOES-19 satellite. Esses equipment captured crucial images before the object was hidden by sunlight between October 18 and 24.
Preliminary research, released on October 28, calculated that the increase in luminosity follows an inverse curve to the seventh power of the distance to the solar center, a remarkable behavior for a celestial body. Essa dynamics were observed at a distance of approximately 1.36 astronomical units, equivalent to 204 million kilometers from Sol.
Amateur astronomers, such as Tai Worakate Boonprod, were the first to record the comet at magnitude 11, making it visible only with medium-sized telescopes. Análises later spectra confirmed the emission of cyanide and ammonia, elements responsible for the bluish color, a striking contrast with the reddish dust observed in July.
The comet’s nucleus, estimated to be 5.6 kilometers in diameter by Telescópio Espacial Hubble in July, is one of the largest ever identified for interstellar objects. The presence of rare metals, such as vaporized nickel, indicates that 3I/Atlas formed under chemical and physical conditions different from those found in our solar system.
Monitoring by space satellites
NASA and ESA satellites played a key role in capturing precise details of the comet during its solar passage. GOES-19’s CCOR-1 instrument was able to resolve a coma 4 arcminutes wide, while SOHO’s C3 coronagraph provided essential colorimetric data.
These observations allowed researchers to detect non-gravitational acceleration, an effect caused by jets of gas that alter the comet’s orbit. Essa is the first time that such a phenomenon has been observed in 3I/Atlas, reinforcing its origin external to our solar system.
The trajectory and its provenance
Comet 3I/Atlas follows a hyperbolic orbit with an eccentricity greater than 6, propelling it at speeds exceeding 210,000 kilometers per hour, a finding that reinforces the hypothesis of its expulsion from another star system approximately 3 billion years ago. Sua discovered, on July 1, 2025, by the ATLAS system in Chile, revealed a celestial body estimated to be up to 11 billion years old, older than Sistema Solar itself, and whose composition includes primitive materials such as volatile ices and halogenated organics, formed before the consolidation of planets. The comet’s linear path has avoided significant interactions with the celestial bodies in our system, although it passed within about 30 million kilometers of Marte on October 3, and observations from NASA’s TESS satellite have detected its activity since May 2025 at a distance of 6.4 astronomical units from Sol.
Chemical composition details
Initial analyzes indicated the significant presence of carbon dioxide and water vapor in the comet, compounds that have been preserved for billions of years. The proximity of Sol causes these elements to sublimate quickly, forming the bright coma that characterizes 3I/Atlas.
The detection of rare metals, such as vaporized nickel, suggests that the comet originated in an environment with formation conditions different from those of our own solar system. Além Additionally, Telescópio Espacial James Webb observed emissions of carbonyl sulfide and water ice in August, indicating that the comet may be a fragment of a distant primordial nebula.
Future observations and missions
ESA’s JUICE (Jupiter Icy Moons Explorer) mission is scheduled to observe comet 3I/Atlas in November 2025, with the aim of capturing its maximum activity from a distance of 19 million kilometers. The collected data, which will include dust and gas spectra, is expected to be transmitted to Terra in February 2026.
Simultaneously, NASA’s Europa Clipper probe is scheduled to cross the comet’s ionic tail between October 30 and November 6. Durante this pass, the probe will perform measurements of charged particles, providing crucial information for mapping the comet’s precise composition and comparing it to comets that originated in our own solar system.
Earth observation opportunities
Comet 3I/Atlas will once again be visible to ground-based telescopes in the constellation Virgem before dawn on November 3, with its luminosity projected to reach magnitude 9 by December, when it will transition to the constellation Leão, providing a unique window for observers.
