An interstellar comet, 3I/Atlas, was identified on July 1, 2025, by the Atlas telescope in Chile. NASA, in partnership with ESA, monitors its hyperbolic trajectory, confirming its origin outside the Solar System. The object’s unusual chemical composition, with a high proportion of carbon dioxide, surprises scientists. It offers insights into the formation of distant star systems.
The 3I/Atlas is the third interstellar object recorded, following ʻOumuamua (2017) and 2I/Borisov (2019). It poses no risk to Earth, remaining 240-270 million kilometers away. Its speed, between 210,000 and 221,000 km/h, increases as it nears the Sun. The perihelion, near Mars’ orbit, occurred in late October 2025.
- Estimated size: from a few hundred meters to 5.6 km in diameter.
- Composition: CO₂ ice to water ice ratio of 8:1.
- Observation: Hubble and James Webb telescopes capture detailed images.
- Visibility: returns to Earth’s view in late November 2025.
NASA coordinates global efforts, using probes like Mars Express to analyze the comet’s spectrum. ESA’s Juice probe also collects data, with results expected in 2026.
Global monitoring effort
NASA and ESA lead the tracking of 3I/Atlas. NASA employs the James Webb telescope for detailed chemical analysis, while ESA uses its Planetary Defense network.
Hubble images reveal a teardrop-shaped dust cocoon. The presence of carbon monoxide and carbonyl sulfide highlights the comet’s uniqueness.
Unusual chemistry uncovered
The high carbon dioxide ratio in 3I/Atlas is atypical for known comets. This suggests a CO₂-rich formation environment or prolonged radiation exposure.
The nickel-to-iron ratio is also unusual, indicating sublimation of metallic compounds. The “anti-tail” facing the Sun, formed by large particles, is a rare phenomenon.
Probe data show an active gas halo, with particle ejection influenced by solar heating. These observations help compare chemical processes in other star systems.
Mysterious cosmic origin
Coming from the Sagittarius constellation, 3I/Atlas has an uncertain origin, dating back billions of years. Gravitational interactions likely ejected it into interstellar space.
NASA rules out alien technology hypotheses, confirming typical comet behavior. Its tail and gas activity align with solar heating patterns.
Tracing its original system is challenging due to cosmic encounters over eons.
Future observations planned
ESA’s Comet Interceptor mission is set to study future interstellar comets. NASA plans to monitor 3I/Atlas until 2026.
The Juice probe may provide new images in February 2026. These data will expand knowledge of cosmic visitors.
Window to distant systems
The 3I/Atlas reveals chemical processes distinct from the Solar System, suggesting it may not be typical in the Milky Way. Its data are crucial for planetary formation theories.
Each observation details how star systems form, offering a unique view of the universe. The comet, crossing the Solar System, brings valuable insights into distant worlds.
