The interstellar comet 3I/ATLAS, detected in July 2025 by the ATLAS system in Chile, completed its perihelion on October 30, 1.4 astronomical units from the Sun. This point marks the closest proximity to the star, around 210 million kilometers, within the orbit of Mars. Now, the object follows a hyperbolic route out of the Solar System, without risk of collision with Earth, according to NASA data.
Astronomers monitor the comet to gather information about its composition and origin in another star system.
The initial discovery occurred in Río Hurtado, and subsequent observations revealed emissions of gases such as carbon dioxide and cyanogen.
- Current speed: approximately 68 km/s, maintaining a stable course.
- Minimum distance to Earth: 1.8 AU, on December 19, 2025.
- Visibility: only with professional telescopes, due to low light.
Close passage to neighboring planets
The 3I/ATLAS crosses the plane of the Solar System, allowing relative approaches to other celestial bodies. Astronomers predict the comet will pass closer to Venus and Mars than Earth in the coming weeks. This configuration facilitates studies of gravitational interactions and dust emissions.
In October, the object already exhibited unusual activity near Mars, with sublimation jets slightly altering its non-gravitational acceleration.
Atypical behavior during the journey
Observations from the James Webb Space Telescope have captured a bright coma dominated by CO₂, stretching thousands of kilometers. The comet’s porous nucleus suggests instability, with variations in luminosity recorded by probes in Martian orbit.
The hyperbolic trajectory, with eccentricity greater than 5, confirms its external origin, different from the elliptical orbits of solar comets.
Preliminary data indicate the absence of brightness bursts, maintaining stable activity even at high distances.
These characteristics differentiate 3I/ATLAS from predecessors, such as 1I/ʻOumuamua and 2I/Borisov.
Global scouting campaign underway
NASA coordinates an international network of telescopes to track the comet between November 2025 and January 2026. The focus is on measuring thermal and spectral emissions to identify organic materials.
Instruments like TESS have detected patterns of negative polarization, linked to dark dust and ice crystals.
This initiative tests protocols for space threats, although 3I/ATLAS does not pose a danger.
- Observation period: from November 27th to January 27th.
- Main targets: chemical composition and non-gravitational forces.
- Participants: ESA agencies and ground-based observatories.
Challenges in detection and monitoring
The comet will be hidden by the Sun until early December, limiting visibility to space telescopes. After perihelion, it reappears in the morning sky, low on the eastern horizon before dawn.
Astronomers face difficulties with the low reflectivity of the object, estimated at 33 billion tons and elongated.
Radio telescopes search for signals of non-random frequency, but so far they only confirm natural behavior.
The interaction with the solar wind causes torques in the tail, visible in images from probes such as Mars Express.
Importance for cosmic studies
3I/ATLAS carries traces of a gas cloud from another planetary system, offering insights into star formation. Its composition may reveal the presence of water and primitive organic molecules, similar to those of the early Solar System.
Spectral analyzes indicate ice crystals and fine dust, potentially influential in the origin of terrestrial life.hundreds of years.
The object traveled billions of kilometers, providing data from unexplored regions.
This unique passage expands knowledge about interstellar dynamics and the evolution of comets in distant environments.
Comparative studies with ʻOumuamua highlight residual accelerations attributed to sublimation, not artificial propulsion.
Future observations and scientific legacy
In December, the comet reaches its closest point to Earth, 270 million kilometers away, allowing for high-precision measurements. Infrared telescopes will track emissions to map the unstable core.
After this phase, 3I/ATLAS accelerates into deep space, crossing the outer heliosphere around 2026.
The legacy includes refining orbital models and preparing for future interstellar visitors.
This analysis reinforces the need for global detection networks, such as ATLAS, for rare events.
