Comet 3I/ATLAS, the third interstellar object confirmed in the Solar System, accelerated after passing through perihelion on October 29, 2025. Discovered on July 1 by the ATLAS telescope in Chile, the celestial body follows a hyperbolic orbit and will leave the system definitively. Its speed reached around 244 thousand km/h, without risk of collision with Earth.
The planet’s minimum approach will occur in December, at 270 million km. NASA and ESA observations highlight unusual composition, with high concentration of carbon dioxide.
- Distance at perihelion: 1.4 AU (210 million km).
- Current speed: 244 thousand km/h.
- Approach to Earth: 1.8 AU in December.
Hyperbolic trajectory confirmed
The orbit of 3I/ATLAS has an eccentricity greater than 6. This confirms its origin outside the Solar System.
The comet will not be captured by the Sun’s gravity. It will pass by Venus in November, 97 million km away.
Astronomers have been monitoring the object since its discovery. Data indicates ejection from another star system billions of years ago.
Unusual chemical composition
Observations from the James Webb Telescope revealed a CO₂-dominated coma. The proportion is eight times greater than that of water.
Presence of carbon monoxide and hydroxyl vapor suggests formation in the environmentcold. Lack of prominent tail differentiates the comet from previous visitors.
Hubble images show reddish coma. This indicates silicate-rich dust.
Intensified global monitoring
Campaign involves observatories in Chile, Hawaii and Australia. Hubble and James Webb Telescopes collected data in July and August.
Missions like Mars Express captured images in October. The comet became invisible during solar conjunction.
He will reappear in December. Visibility will require professional equipment.
The International Asteroid Warning Network refines orbital measurements. Exercises are not related to planetary defense.
Detailed Hubble Observations
Images captured in July reveal diffuse hair. Growing tail points to cometary activity.
The nucleus remains compact. Ejection of gases causes non-gravitational acceleration.
Data confirms mass loss of more than 13%. Brightness increased fivefold between September and October.
Post-perihelion activity
The comet exhibited a jet of gas towards the Sun. Observations from Gemini South recorded a tail of 56 thousand km.
Activity remained stable without outbreaks. Brightness reached magnitude 7-8 near perihelion.
Ancient origin revealed
Estimated age ranges from 7 to 14 billion years. The object precedes the Solar System.
Trajectory analysis suggests interactions in distant systems. Composition challenges traditional comet models.
Presence of organohalogens and absence of associated iron-nickel intrigue scientists.
Future planetary passages
The 3I/ATLAS will pass by Jupiter in March 2026. Distance will be 54 million km.
Trajectory will lead to interstellar space. Departure will take place in January 2026.
Contributions to astronomy
Study offers unique insight into interstellar chemistry. Data collected until January 2026 will assist planetary formation models.
Observations from probes such as Juice will complement analyses. The comet represents a cosmic time capsule.
3I/ATLAS continues to accelerate out of the Solar System. Monitoring continues until loss of visibility.