NASA has intensified monitoring of the interstellar comet 3I/ATLAS, detected on July 1, 2025 by the ATLAS telescope, in Chile, due to its hyperbolic orbit and unusual chemical composition. The object, which reached perihelion on October 29, 2025, 210 million kilometers from the Sun, displays a coma with eight times more carbon dioxide (CO₂) than water, something never seen in comets. The International Asteroid Warning Network (IAWN) organizes a global training, from November 27, 2025 to January 27, 2026, to refine orbital measurements. The high speed, exceeding 210 thousand km/h, and variations in brightness make predictions difficult.
- Interstellar origin confirmed by hyperbolic orbit.
- Core estimated to be between 320 meters and 5.6 kilometers in diameter.
- Over 7 billion years old, predating the Solar System.
- Observations from the James Webb Telescope reveal atypical chemical composition.
Chemical composition surprises astronomers
The James Webb Space Telescope (JWST) identified a coma dominated by carbon dioxide, with proportions eight times greater than that of water, challenging traditional models of comets. This composition suggests formation in cold regions, possibly beyond the CO₂ frost line in distant star systems.
The low presence of water, combined with hydroxyl (OH) emissions 450 million kilometers from the Sun, indicates intense chemical activity, even at great distances. Data from NASA’s Swift telescope, checksupport the decomposition of water, but the predominance of CO₂ remains unusual.
Hyperbolic trajectory and tracking challenges
The hyperbolic orbit of 3I/ATLAS, with eccentricity above 6, confirms that the comet will not be captured by the Sun and will leave the Solar System in 2026. It passed 28 million kilometers from Mars on October 3, 2025 and will approach Jupiter in March 2026.
The object reached a speed of 244 thousand km/h after perihelion, making accurate orbital calculations difficult. IAWN coordinates telescopes in Hawaii, Chile and Australia to calibrate tracking algorithms.
Particle jets directed towards the Sun, forming an anti-solar tail, distort the center of brightness, generating errors of up to 20% in measurements. The global campaign aims to reduce these uncertainties.
Hubble and James Webb Telescopes captured images detailing the coma and a 56,000-kilometer dust tail observed in August 2025.
Possible extraterrestrial origin sparks debate
A study led by Harvard astrophysicist Avi Loeb suggests that 3I/ATLAS may be an alien artifact due to its retrograde orbit and atypical composition. The hippothesis, although controversial, is based on orbital synchronization with planets and the absence of typical cometary gases.
The scientific community, however, focuses on the natural origin of the comet, estimated at more than 7 billion years old. Data collected until January 2026 will be crucial to clarify its formation.
Intensified global monitoring
IAWN, supported by the UN, conducts an unprecedented exercise with an interstellar object, integrating data from ground-based and space telescopes. ESA’s Juice probe will observe the comet in November 2025, from 64 million kilometers away.
The comet and the formation of the universe
3I/ATLAS, the third interstellar confirmed after ‘Oumuamua and 2I/Borisov, offers clues about the formation of distant planetary systems. Its composition rich in CO₂ and organohalogens suggests chemical processes in cold regions of the cosmos. The absence of iron associated with nickel challenges traditional models, reinforcing the importance of continuous monitoring. The analysis of its trajectory and chemistry can expand knowledge about the primitive universe, prior to the Solar System.
