The interstellar comet 3I/ATLAS is on its way out of the solar system after revealing unprecedented data about its chemical composition. Observações carried out by Telescópio Espacial James Webb (JWST) and NASA’s SPHEREx mission confirmed the presence of methane, water and organic molecules in the object. The celestial body is the third visitor from outside our system ever detected by modern astronomy. Pesquisadores of Caltech published detailed results in the magazineThe Astrophysical Journal Lettersthis week.
Analysis indicates that the object traveled the galaxy for at least a billion years before crossing Terra’s neighborhood. Durante passing, which reached the closest point to Sol in October 2025, the comet demonstrated unique behavior as it began to release internal gases. The phenomenon allowed scientists to observe not only the surface hit by cosmic rays, but the original material preserved inside since its formation in another star system.
James Webb detects methane after solar core heating
The discovery of methane occurred at a specific moment in the trajectory of 3I/ATLAS, when it was already moving away from Sol in December 2025. Inicialmente, the comet’s outer crust, punished by billions of years of space radiation, showed few signs of volatile gases. With the increase in internal temperature caused by the solar approach, the deep ice layers began to melt and sublimate.
The degassing process revealed that the methane was stored beneath the surface, protected from galactic irradiation. Esta observation is considered a milestone as it offers clues about the object’s originating environment. The abundance and proportion of chemical compounds in interstellar comets act as a “fingerprint” of the thermal and chemical conditions of other distant planetary systems.
Interstellar Cometa shows brighter brightness than previous visitors
Diferente from its predecessors, 1I/’Oumuamua and 2I/Borisov, 3I/ATLAS stood out for the intensity of its brightness and cometary activity. Enquanto ‘Oumuamua did not exhibit the characteristic tail of dust and gas, the new visitor allowed the use of advanced infrared instrumentation. The team led by Matthew Belyakov used James Webb to map signals at wavelengths ten times longer than human vision can reach.
Data collected by the SPHEREx mission and JWST cataloged the following components in the comet’s coma:
- Partículas of rocky dust rich in minerals;
- Vapor of water released by internal defrosting;
- Dióxido of carbon in gaseous state;
- Metano and several complex organic molecules.
Objeto more than a kilometer wide leaves the solar system
With dimensions estimated at more than a thousand meters in diameter, 3I/ATLAS has already crossed the orbit of Júpiter on its farewell path. The high speed ensures that the celestial body never returns to the gravitational influence of Sol. Para the scientific community, the short observation period was a rare opportunity to study a “planetesimal” — a planetary building block — coming from a remote part of Via Láctea.
Studying these fragments helps understand how Terra and other planets formed from rock and ice billions of years ago. Como, 3I/ATLAS has a chemistry distinct from objects born in our solar system, it serves as a mobile comparative astrophysics laboratory. Monitoring will continue as long as the comet’s thermal signals are detectable by long-range instruments.