The ATLAS telescope at Chile detected the 3I/ATLAS object on July 1, 2025, confirmed as the third interstellar to visit Sistema Solar.
Astronomers from several institutions analyze data that indicate an origin outside our stellar system, with a speed of around 220 thousand km/h.
The discovery comes amid advances in space observatories, such as Hubble, which captured detailed images of the icy core.
- Hyperbolic speed confirms trajectory not linked to Sol.
- Methanol-rich composition suggests ancient formation environment.
- Closest approach to Terra scheduled for December 19, 2025.
Initial detection details
Preliminary observations from the ATLAS telescope, funded by Nasa, identified the object at Río Hurtado, at Chile, with backdated data from June.
Minor Planet Center experts processed the images and assigned the designation 3I, marking it as interstellar, after analyzing orbital eccentricity greater than 6.
The team coordinated global efforts to track the movement, avoiding confusion with local asteroids.
The official announcement came on July 2, mobilizing telescopes such as the one at Lowell, at Arizona, and the Canada-France-Hawaii, at Havaí.
Chemical composition revealed
Spectra obtained by the Atacama Large Millimeter/submillimeter Array detected methanol in a proportion of 8% of the vapors emitted, four times above the average in solar comets.
Hydrogen cyanide also appears at high levels, forming an active coma with a tail of plasma and dust.
These carbonic compounds indicate formation processes in distant stellar systems, possibly older than ours.
- Methanol: precursor of complex organic molecules.
- Cyanide: linked to reactions that simulate blocks of primitive life.
- Methanol-cyanide ratio: highest ever recorded in similar objects.
Trajectory and planetary approaches
The object reached perihelion on October 29, 2025, at 1.4 astronomical units from Sol, with no fragmentation observed.
Its route aligns with the ecliptic plane to within five degrees, approaching Vênus, Marte, and Júpiter in calculated sequences.
Data from ExoMars Trace Gas Orbiter, from Esa, refined the position in October, reducing uncertainty by a factor of 10 during passage through Marte.
The speed relative to Sistema Solar reaches 250 thousand km/h, guaranteeing permanent exit to interstellar space.
Space mission observations
Telescópio Espacial Hubble recorded images on July 21 and November 30, 2025, revealing a 440-meter to 5.6 km diameter core shrouded in teardrop-shaped dust.
The Nasa mission Psyche captured four exposures in September, 53 million km away, using multispectral cameras to map solar reflections.
The Perseverance rover at Marte detected the comet as a faint speck on October 4, while Juice at Esa obtained high-resolution views in November.
These synchronized collections provide the most complete catalog of an interstellar visitor to date.
Anomalies and scientific debates
Solar jets of up to 23,000 km emerge from the nucleus, with brightness patterns that do not follow traditional cometary models.
The anti-tail reversed post-perihelion orientation, suggesting rapidly evaporating fragments or radiation-resistant materials.
Astronomers note X-ray emissions and pulses of luminosity, defying explanations based solely on ice sublimation.
With no evidence of violent flares, activity remains stable, contrasting with comet 2I/Borisov.
Avi Loeb’s theories about the object
Harvard’s teacher, Avi Loeb, coordinates Projeto Galileo to monitor unidentified phenomena and highlights eight anomalies in 3I/ATLAS.
He proposes that orbital alignment and non-gravitational accelerations increase the probability of technological origin to 40%, compared to ‘Oumuamua.
Loeb argues that the size and mass, a million times greater than precursors, imply a low natural probability of detection.
In recent publications, he speculates about the release of smaller probes near Júpiter in March 2026, without stating absolute certainty.
Implications for astrochemistry
The presence of organic precursors in 3I/ATLAS reinforces hypotheses of panspermia, where comets transport vital ingredients between stellar systems.
Analysis indicates that the object was formed in a protoplanetary disk with a carbon-rich chemistry, possibly in a star more massive than Sol.
Kinematic age studies suggest aging by cosmic radiation, estimated at billions of years of interstellar travel.
These data expand understanding of planetary diversity beyond Sistema Solar, guiding future searches for habitable exoplanets.
Preparations for Earth Observation
Amateurs with small telescopes can view 3I/ATLAS in the pre-auroral sky starting December 12, 2025, at 90 degrees from Sol.
Opposition occurs on January 22, 2026, when the object will be visible all night, although fainter due to increasing distance.
Observatories like Rubin plan continuous surveys to intercept similar visitors, preparing rendezvous missions.
These windows offer a unique chance to collect data before the object leaves definitively.
