The Breakthrough Listen project used the Telescópio Green Bank, 100 meters in diameter, to observe the interstellar comet 3I/ATLAS on December 18, 2025. The session lasted five hours and occurred one day before the object’s closest approach to Terra, recorded on December 19. Nenhum signal of technological origin was identified after detailed analysis of the data collected.
Comet 3I/ATLAS, discovered on July 1, 2025, follows a hyperbolic trajectory that confirms its origin outside of Sistema Solar. Sua passage offered a rare opportunity for close observations, about 270 million kilometers from Terra.
The team responsible alternated the telescope’s pointing between the comet and adjacent regions of the sky to eliminate external interference. Essa technique made it possible to isolate possible emissions originating exclusively from the object under study.
Discovery and trajectory of comet 3I/ATLAS
The object was initially identified by the ATLAS system, which monitors asteroid threats. Cálculos orbitals indicated a speed greater than the escape of Sistema Solar, characterizing it as the third confirmed interstellar visitor.
During perihelion, at the end of October 2025, the comet reached a minimum distance from Sol of approximately 1.4 astronomical units. Essa proximity activated its coma and tail, visible in images captured by several instruments.
Observed characteristics of the object
3I/ATLAS presents a gaseous coma and behavior typical of known comets. Telescópios like Hubble recorded their activity on multiple dates throughout 2025.
The detected chemical composition includes elements common in Sistema Solar comets. Não there is evidence of anomalies that suggest artificial origin in none of the analyzes carried out.
Radio observation methodology
The scan covered a frequency range between 1 and 12 GHz, considered ideal for possible technological communications. The Green Bank Telescope, one of the most sensitive on the planet, guaranteed high resolution throughout the session.
The researchers applied a pointing standard known as ABACAD. Esse method consists of regular alternations every five minutes to differentiate fixed from mobile signals.
Nine initial candidates emerged in the raw data. Análises later classified all as radio frequency interference generated by human equipment on Terra or in orbit.
The procedure eliminated known terrestrial sources by comparison with control observations. Assim, the absence of narrow or modulated emissions from the comet was confirmed.
Importance of negative results
Null results contribute to scientific advancement by establishing upper limits for possible transmissions. In the case of 3I/ATLAS, the presence of continuous transmitters above certain power levels was excluded.
Similar observations have occurred with previous interstellar objects. Elas reinforce the methodology used in searches for technosignatures in transient visitors.
Context of known interstellar objects
To date, only three confirmed objects have an origin external to Sistema Solar. The first, 1I/’Oumuamua, detected in 2017, had an unusual elongated shape.
The second, 2I/Borisov, identified in 2019, exhibited classic cometary characteristics. 3I/ATLAS follows a similar pattern to Borisov in several aspects.
- Hyperbolic trajectory with eccentricity greater than 1
- Interstellar velocity relative to Sol
- Activation of coma when approaching perihelion
- Volatile composition detected spectroscopically
Other complementary observations
The Parker Solar Probe probe captured images of the comet between October and November 2025. Esses records showed details of the interaction with the solar wind during its passage through perihelion.
Telescópio Espacial Hubble held multiple sessions throughout the year. The photos revealed the evolution of the tail and coma at different distances.
Space agencies coordinated efforts to maximize data collection. The close observation window allowed studies that would not be possible on more distant objects.
Green Bank Telescope Technical Details
Installed on Estados Unidos, the instrument has a diameter of 100 meters and operates in an environment protected from radio interference. Sua reflective surface allows high sensitivity across a broad spectrum of frequencies.
The telescope regularly participates in projects searching for extraterrestrial signals. The infrastructure supports prolonged observations with high pointing accuracy.
Analysis of detected candidates
The initial nine signals showed characteristics consistent with known human sources. Satélites communication and terrestrial transmissions explained each case after data crossing.
Filtering automatically removed repetitive patterns associated with terrestrial technology. The process left only cosmic background noise in the final records attributed to the comet.
This step demonstrates the robustness of the protocol against false positives. Ela ensures reliability in non-detection statements.
Contributions to future research
Accumulated experience refines protocols for subsequent interstellar objects. Melhorias include expansion of frequency bands and integration with other telescopes.
The data obtained remains available for independent analysis. Pesquisadores can reapply more advanced algorithms as technology evolves.
Monitoring transient visitors remains a priority in astronomy. Cada passage offers a unique chance to study primordial material from other star systems.
The absence of technosignatures reinforces the natural profile of 3I/ATLAS. Todas accumulated evidence points to conventional cometary origin despite external provenance.
Legacy of the observation campaign
The initiative demonstrates scientific commitment to verifying even unlikely hypotheses. Testar possibilities eliminate uncertainties and establish solid foundations for interpretations.
Coordination between international institutions facilitated the rapid execution of the project. The immediate response to the window of opportunity maximized the scientific return.
Comet 3I/ATLAS is now moving away again towards interstellar space. Sua trajectory will take you beyond the limits of Sistema Solar in the coming years.
Detailed logs preserve valuable information about external object dynamics. Eles will serve as a reference for comparisons with future similar discoveries.
