The international astronomical community raised its level of attention after the identification of the interstellar comet 3I/ATLAS, a celestial body that presents unique and unprecedented characteristics compared to previous visitors to our solar system. Detectado initially by the ATLAS astronomical survey system in July 2025, the object was confirmed as the third visitor from interstellar space, following in the footsteps of the famous ‘Oumuamua and 2I/Borisov. The discovery mobilized space agencies around the globe due to physical behaviors that defy conventional comet classifications.
What distinguishes this new visitor is not only its remote origin, but the combination of an extraordinary speed, estimated at more than 100,000 kilometers per second, with the emission of anomalous radio signals. Esses factors led Administração Nacional of Aeronáutica and Espaço (NASA) to activate specific planetary defense protocols, establishing rigorous and continuous monitoring. The main objective is not only to ensure orbital safety, but also to take advantage of an unprecedented scientific opportunity to collect data on the formation of distant star systems.
Physical characteristics and composition of the nucleus
Researchers at Agência Espacial Europeia (ESA) describe 3I/ATLAS as a predominantly rocky body that was likely ejected from its original star system millions of years ago. The dimensions of the nucleus are significant, varying between 320 meters and 5.6 kilometers in diameter, composed of a complex mixture of gases and cosmic dust. Preliminary analysis suggests that its chemical composition differs substantially from comets formed in our own system, offering valuable clues about the abundance of elements in other regions of the galaxy.
The object’s high speed and steep inclination of its orbit confirm that it is not gravitationally bound to Sol, classifying it as a true interstellar traveler. Observatórios around the world are refining this data to better understand the comet’s internal structure and the dynamics of its tail of dust and gas as it interacts with the solar environment.
Investigation of radio emissions
One of the most intriguing aspects of this phenomenon was the detection of radio signals emanating from the comet in October 2025, captured by the MeerKAT radio telescope, located at África. Although radio activity is a possible natural process on celestial bodies, the clarity and intensity observed in 3I/ATLAS are rare for an object in this category. Cientistas quickly ruled out any artificial origin, confirming that the emissions are consistent with natural physical processes in the comet’s active nucleus, likely resulting from the interaction of volatile materials with the solar wind.
This discovery validated the object’s classification as a dynamic comet and inaugurated a new methodology for studying distant visitors. The use of radio astronomy now makes it possible to investigate processes that traditional optical observation cannot capture, such as the subsurface structure of the nucleus and the energetic reactions in its coma.
Trajectory and planetary security
Despite the mobilization of planetary defense departments, space agencies ensure that the trajectory of 3I/ATLAS presents no risk of collision with Terra. Orbital calculations indicate that the point of closest approach occurs in December 2025, maintaining a safe distance of around 27 million kilometers from our planet. The Essa distance, although safe, is close enough to allow detailed observations by high-precision instruments such as the Very Large Telescope (VLT) on the Chile and the Telescópio Espacial Hubble.
The passage of this celestial body serves as a practical exercise for the international planetary defense network, testing the response and coordination capacity between entities such as NASA and ESA. The real-time exchange of information and validation of tracking procedures are fundamental legacies of this event, preparing humanity to identify and monitor potential future threats with greater effectiveness and precision.