Comet 3I/ATLAS, third interstellar object, emits radio waves and mobilizes NASA monitoring
The ATLAS system detected the interstellar comet 3I/ATLAS on July 1, 2025 at the Río Hurtado observatory in Chile. The object, the third confirmed origin outside the Solar System, follows a hyperbolic trajectory at around 100,000 km/h in relation to the Sun. NASA mobilized the planetary defense team after capturing radio waves at a frequency of 1.6 GHz.
The comet’s nucleus has an estimated diameter of between 320 meters and 5.6 kilometers and is surrounded by a coma of gas and dust. The closest approach to Earth will occur on December 19, 2025, at 270 million kilometers.
Detection and initial characteristics
The ATLAS telescope, operated by the University of Hawaii Astronomy Institute, identified the object as a possible threat in July. Hubble observations confirmed intermediate dimensions.
The trajectory shows slight non-gravitational acceleration, typical of active comets. The high speed indicates origin in another star system millions of years ago.
Registered radio signal
The MeerKAT radio telescope in South Africa captured the signal on October 24, 2025. The frequency coincides with hydroxyl lines produced by ice sublimation.
Scientists classify the emission as natural and constant. The analysis excluded external or artificial interference.
Defense protocol activation
NASA convened the Planetary Defense Coordination Office in August 2025. The procedure follows standard procedures for objects of unknown origin.
Telescopes such as the James Webb and Very Large Telescope collect spectral data from the nucleus and coma.
Trajectory and safety distance
The comet enters and leaves the Solar System in an open hyperbolic orbit. The minimum distance to Earth is equivalent to almost twice the average separation between the Sun and Mars.
Calculations by NASA and the European Space Agency rule out the risk of collision. The object will not be captured by solar gravity.
Composition and comparisons
The surface reflects little light, similar to Kuiper belt comets. The absence of intense degassing differentiates 3I/ATLAS from 2I/Borisov.
- Confirmed presence of water ice and volatile compounds
- Activity increases as perihelion approaches
- Spectral reflection indicates dark organic material
- Comparison with ‘Oumuamua reinforces extrasolar origin
Monitocontinuous ment
Radio telescopes in several countries monitor variations in the signal. Brightness fluctuations result from asymmetric ejections of material.
Observations continue until the comet moves away in 2026. The data updates models of formation and ejection of bodies in other stellar systems.
The radio signal remains stable and compatible with natural processes of an active comet. The combination of trajectory, composition and emission reinforces the classification as the third confirmed interstellar visitor after ‘Oumuamua and Borisov.
