The interstellar object 3I/ATLAS will reach its closest approach to Earth on December 19, 2025, at around 270 million kilometers. Detected in July by the ATLAS system in Chile, the comet follows a hyperbolic trajectory, confirming its origin outside the Solar System. There is no risk of collision, according to data from NASA and ESA.
Space agencies coordinate intense observations with telescopes such as Hubble and James Webb. Perihelion occurred on October 30, 1.4 astronomical units from the Sun.
- Minimum distance to Earth: 1.8 AU.
- Speed: over 200 thousand km/h.
- Composition: rich in CO2, water and metals such as nickel.
Discovery and trajectory of the cosmic visitor
Astronomers identified 3I/ATLAS on July 1, 2025. Pre-discovery observations date back to June. Its hyperbolic orbit, with eccentricity above 6, indicates that it is not tied to solar gravity.
The comet passed close to Mars in October, allowing images from probes such as ExoMars. After perihelion, it emerged with reduced brightness, but visible in constellations such as Virgo and Leo.
Research reveals an age between 7.6 and 14 billion years. It belongs to the thick disk of the Milky Way, with low metallicity.
Unusual features observed
The 3I/ATLAS presented anti-tail pointing towards the Sun in July and August. After perihelion, images from November show seven distinct jets and a 500,000 km halo.
Non-gravitational acceleration detected, similar to ‘Oumuamua. Emissions include nickel and iron vapor at cold distances.
- Jets: possibly sublimation of volatiles.
- Absence of clear tail in some images.
- Unexpected color change and shine.
International monitoring efforts
NASA, ESA and global observatories have activated tracking campaigns. Missions like Hera and Juice have adjusted instruments to capture data.
IAWN exercises improve planetary defense protocols. Ground-based telescopes in Chile and Hawaii record orbital variations.
Observations continue until March 2026, when the comet will cross Jupiter’s orbit.
Chemical composition revealed by telescopes
James Webb detected dominant CO2, water, CO and carbonyl sulfide. Swift confirmed water vapor and OH.
Presence of atomic nickel indicates ancient origins. Radiated crust layereach changes surface.
Polarimetric analyzes show distinct light reflection from solar comets.
Visibility and opportunities for astronomers
The comet reaches magnitude 12 in December, visible with amateur telescopes. Best period: early December, southern hemisphere.
Does not shine brightly with the naked eye. Tools like NASA Eyes simulate trajectory in real time.
Debates on anomalous accelerations
Studies point to radial and transverse forces in addition to gravity. Hypotheses include gas release or directional jets.
Avi Loeb suggests technological possibility, but the scientific community attributes it to natural processes. Absence of modulated signals reinforces cometary origin.
Predicted Solar System Exit
After approaching Earth, 3I/ATLAS heads to interstellar space. It will pass close to Venus in November and Jupiter in 2026.
Escape velocity maintains a straight trajectory. Leaves a legacy of data on distant planetary formations.
Scientific legacy of 3I/ATLAS
The visitor provides samples from another star system. Refines models of cosmic chemical evolution.
Increases future detections with telescopes like Vera Rubin. Contributes to the understanding of galactic disksantigos.
