Comet 3I/ATLAS exhibits unprecedented cryovolcanic eruptions in 2025 revealing cosmic secrets

Spanish scientists from Observatório Montsec, using Telescópio Joan Oró, recorded in October 2025 evidence of cryovolcanic eruptions on the interstellar comet 3I/ATLAS. Este is the third object of its kind detected in our Sistema Solar, and its close approach to Sol has revealed a phenomenon that suggests a composition rich in ice and primitive materials, with striking similarities to objects located beyond Netuno’s orbit. The discovery, driven by the ATLAS system at Chile in July of the same year, underscores the importance of cosmic visitors for understanding the formation of distant star systems.

The comet travels at an impressive speed of 221 thousand km/h, following a hyperbolic orbit that confirms its origin in another star system. The eruptions intensified 378 million kilometers from Sol, revealing spiral structures on its surface and offering crucial data about their nature.

This cosmic activity offers clues about chemical conditions in distant star systems. Dentre the information collected, the following stand out:

Cryovolcanic phenomenon in evidence

Astronomers have been monitoring comet 3I/ATLAS since July 2025, but activity increased dramatically in October. Perihelion occurred on October 29, 2025, at 1.36 astronomical units from Sol. Imagens of Telescópio Joan Oró captured high-resolution jets, previously unseen, complemented by regional observatories on Espanha. The sublimation of dry ice generated steam and dust, visible at specific wavelengths, confirming the nature of the eruptions and the complexity of the observed phenomenon.

Cosmic composition and similarities

Comet 3I/ATLAS has spectroscopic features that link it to trans-Neptunian objects, such as ice-rich dwarf planets. Análises compared its composition to carbonaceous chondritic meteorites, found in Antártida, indicating inheritance of primitive materials and analogous formation processes in different systems.

These materials contain natural and volatile metals, crucial elements in the formation of the Earth’s atmosphere. Pesquisadores noticed internal chemical reactions, driven by solar heating, releasing gases such as carbon monoxide and cyanide. The presence of atomic nickel vapor corroborates the hypothesis of a preserved and complex metallic nucleus.

Mechanism of singular eruptions

Cryovolcanoes emerge on icy bodies when internal heat melts ice, expelling steam and dust. In the case of 3I/ATLAS, the process differs because it depends on the corrosion of pristine materials. Solar heating exceeded the threshold for sublimation of solid CO2, allowing the flow of oxidizing liquids that react with metallic grains, generating the observed spiral jets, an externally driven phenomenon.

Studies indicate that this activity is the main explanation for the sudden brightness of the comet 378 million kilometers from Sol. Este phenomenon, documented in October 2025, offers a rare opportunity to observe the dynamics of an interstellar body in real time, providing crucial data for astrophysics and comparative planetary geology.

Cosmic Visitor Trajectory and Data

The comet entered our Sistema Solar from the direction of Sagitário, close to the galactic center. Sua’s excessive velocity confirms that it is not linked to solar gravity, pointing to an origin in Via Láctea’s thick disk, estimated to be billions of years old.

Telescópio Espacial Hubble measured its size at between 440 meters and 5.6 kilometers. The mass, for a body 1 km in diameter, exceeds 600 million tons, highlighting the density and volume of material that composes it.

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The comet’s closest approach to Terra is scheduled for December 19, 2025, at a distance of 270 million kilometers, making it visible with amateur telescopes. Sua’s definitive departure from Sistema Solar is scheduled for 2026, allowing continuous observations until its complete removal.

Space collaboration in observation

Nasa coordinated campaigns with probes such as Perseverance in Marte and MAVEN, capturing images of the gas coma. Mars Reconnaissance Orbiter refined the trajectory in October 2025, reducing uncertainty by a factor of ten.

James Webb Space Telescope detected abundant carbon dioxide, with traces of water ice and carbonyl sulfide. Esses data reveals a halo of gas and dust, with cyanide emissions similar to solar comets, providing a complete picture of its volatile composition.

Spectroscopic analyzes and composition

Photometry tracked the increasing pre-perihelion brightness, with peaks at infrared wavelengths, essential for quantifying the intensity of the eruptions.

Comparisons with Antarctic samples confirmed similarities with carbon-rich CR chondrites, indicating a common origin in stellar nebulae.

These meteorites represent remnants of the early solar nebula, suggesting that the comet may be a fossil from a young star system.

The radio detection at 1420 MHz, although natural, ruled out speculation about non-natural extraterrestrial origins, focusing on the astrophysical nature of the object.

Relevance and future prospects

Interstellar objects like 3I/ATLAS act as time capsules, preserving the chemistry of other stellar systems and helping to understand distant planetary formation, driving proposals for future interceptor missions.