The interstellar comet 3I/ATLAS was detected on July 1, 2025, by the ATLAS telescope in Chile. The object shows a chemical composition with high levels of carbon dioxide, exceeding water in an eight-to-one ratio. NASA imposes restrictions on releasing detailed data since October, citing budget limitations due to a U.S. government shutdown.
Astronomers from various countries gather information through independent observatories. The hyperbolic trajectory confirms origin outside the Solar System. The comet activated at 6.4 astronomical units from the Sun in May 2025.
- Closest approach to Mars occurred on October 3.
- Orbital probes captured images, but analyses remain pending.
- Perihelion is scheduled for October 30.
Unusual chemical composition
Spectroscopic analyses show predominance of carbon monoxide. Volatile compounds indicate exposure to cosmic radiation for billions of years.
The nucleus ranges between 300 meters and 5.6 kilometers in diameter. Active surface reaches over 8% of the total.
Absence of heavy metals suggests connection to ancient stars. Estimated age falls between 7.6 and 14 billion years.
Monitoring by agencies
Collaboration with the European Space Agency fills data gaps. Mars Express and ExoMars Trace Gas Orbiter probes recorded infrared images.
Observatories inChile and Europe track the object since May. James Webb Telescope confirmed ultraviolet emissions in August.
Hubble Telescope plans observations in November for spectroscopy. Trajectory passes at 1.4 astronomical units from the Sun.
Trajectory and speed
Speed ranges from 210 to 221 thousand kilometers per hour. Increases occur during solar approach.
Estimated mass is 1,000 to 10,000 times greater than typical comets. No signs of fragmentation so far.
Minimum distance from Earth will be 240 million kilometers. Unusual negative polarization sparks classification debates.
Ground-based observations
ATLAS telescope in Río Hurtado confirmed hyperbolic orbit. Activity started in May with steady brightness until September.
Vera C. Rubin Observatory captured images in June. Transiting Exoplanet Survey Satellite recorded pre-discovery data.
Emission records
Symmetric patterns of gas traces appear in captures. Core vibrations indicate complex internal structure.
Metallic grains are present on the surface. Accelerations near planets surprise gravitational models.
International collaborations
Proposals include integration of multi-mission data. Southern Hemisphere observatories prioritize nighttime sessions.
Bayesian analyses calculate origin probabilities. High-resolution images are expected after perihelion.
These joint efforts extend the observational window before the comet exits the Solar System, projected for December 2025, when ground telescopes can still record it during departure trajectories.
