NASA has confirmed that comet 3I/ATLAS, discovered on July 1, 2025 by the ATLAS telescope in Chile, follows a hyperbolic orbit, indicating that it will not be captured by solar gravity and will leave the Solar System after its passage. The object, identified as the third interstellar to cross our system, reached perihelion on October 29, 1.4 astronomical units (210 million km) from the Sun. Its speed increased to around 244 thousand km/h, and it will approach Earth in December, at 270 million km, without risk of collision. The carbon dioxide-rich composition and the absence of a typical cometary tail arouse scientific interest.
Observations from the James Webb Space Telescope revealed a coma dominated by CO₂, with a proportion eight times greater than that of water, something unusual in comets. The scientific community is monitoring the object to understand its origin, estimated to be between 7 and 14 billion years old.
- Current speed: Approximately 244 thousand km/h.
- Perihelion: October 29, 2025, 1.4 AU from the Sun.
- Minimum distance from Earth: 1.8 AU (270 million km) in December.
Unique chemical properties
3I/ATLAS exhibits a distinct chemical composition, with a high concentration of carbon dioxide. James Webb data, collected in August, shows carbon monoxide and hydroxyl vapor, suggesting formation in a cold, distant environment.
The absence of a prominent tail differentiates the comet from others, such as 2I/Borisov, and raises questions about its classification.
Intensive monitoring
NASA coordinates observations with telescopes like Hubble and space missions, including Mars Express, which captured data in October.
The comet was invisible during the solar conjunction, but will reappear in December, visible only with professional telescopes.
The International Asteroid Warning Network (IAWN) conducts training to refine orbital measurements, unrelated to planetary defense.
The object will pass Venus in November, 97 million km away, and Jupiter in March 2026, 54 million km away.
Interstellar Origin
With an estimated age greater than that of the Solar System, 3I/ATLAS may have been ejected from another star system billions of years ago. Its hyperbolic orbit, with eccentricity above 6, confirms that it will not be stuck to the Sun. Analysis of its trajectory suggests gravitational interactions in the Sun.distant stellar themes, offering clues about the formation of planets in other stars.
Global Observation Campaign
The monitoring campaign, which began in November 2025, involves observatories in Chile, Hawaii and Australia. Hubble images, captured in July, show a reddish coma, indicating silicate-rich dust.
Scientific contributions
The 3I/ATLAS study is a unique opportunity to understand interstellar chemistry. The presence of organohalogens and the absence of iron associated with nickel challenge traditional comet models. Astronomers hope that data collected until January 2026, when the comet will be less visible, will reveal more about its formation and trajectory.
