Terrestrial observatories recorded radio emissions from the interstellar comet 3I/ATLAS, discovered in July 2025 by the ATLAS system in Hawaii. The object, the first confirmed comet of origin outside the Solar System, approaches the Sun and will go through perihelion in December 2025. NASA and the UN have included the celestial body on the list of potentially dangerous objects due to the trajectory that will cross the Earth’s orbital plane.
The signals were initially captured by a station in South Africa and confirmed by global radio telescope networks. Experts attribute the emissions to the interaction between released gases and the solar wind. There is no evidence of artificial origin.
The current speed of 3I/ATLAS exceeds 60 kilometers per second. The minimum distance from Earth will occur in December, still in the orbital refinement phase.
Object characteristics
The comet has a nucleus estimated to be tens of kilometers long. Elon Musk compared its approximate dimensions to the island of Manhattan during an update on the X network.
Spectroscopic analyzes identified water, carbon monoxide and methane in the composition. These volatile compounds generate the observed coma as the object heats up.
The Hubble Space Telescoperecorded detailed images in July 2025, when the comet was 445 million kilometers from Earth.
Source of detected signals
Radio emissions have a pattern compatible with natural sublimation processes. Released gases form jets that interact with charged solar particles.
NASA scientists ruled out any hypothesis of an artificial signal after complete spectral analysis. The phenomenon occurs in a similar way in comets in the Solar System when close to the Sun.
Observatories such as MeerKAT, in South Africa, maintain continuous monitoring of emitted frequencies. The data helps map core activity in real time.
Heightened monitoring
NASA activated planetary defense protocols in coordination with international agencies. Terrestrial and space telescopes follow the trajectory with daily updates.
Current forecasts indicate safe passage, without risk of collision with Earth. The safety margin will be confirmed in the coming weeks with new orbital calculations.
- ATLAS Observatory: responsible for the initial discovery
- Hubble: high-resolution images
- MeerKAT: primary detection of radio signals
- Global network: continuous orbit refinement
Composition and behavior
3I/ATLAS has been traveling through interstellar space for billions of years from its home system. The composition rich in volatiles suggests formation in a cold environment similar to the Oort cloud.
The intense release of gases creates an extensive tail visible at specific wavelengths. The increase in activity occurs precisely due to the approach to the Sun, which increases the surface temperature of the nucleus and accelerates the sublimation of frozen compounds.
Mission Next Steps
Agencies prepare the use of probes to collect data during the closest passage. Planning includes possible interception missions for on-site analysis of the internal structure.
The results obtained will serve to improve defense models against future interstellar objects. The accumulated experience represents advances in knowledge about bodies coming from other stellar systems.