The American space agency NASA activated the planetary defense protocol this week, after astronomers identified changes in the trajectory and brightness of the interstellar comet 3I/ATLAS. The object, discovered in July 2025 by the ATLAS telescope in Chile, presents deviations that complicate orbital predictions. The measure occurs without immediate risk to Earth, but aims to improve global monitoring. The collaboration involves the International Asteroid Warning Network (IAWN) and the Minor Planet Center at Harvard.
The comet reached perihelion on October 30, 2025, near the orbit of Mars, about 210 million kilometers from the Sun. Telescopes such as Hubble and James Webb have captured data that reveal unusual activity for interstellar visitors. Experts tweak algorithms to track objects with hyperbolic trajectories.
The initial detection occurred 450 million kilometers from the Sun, with hydroxyl emissions confirming its external origin. The speed of 3I/ATLAS exceeds 210 thousand km/h, reinforcing its classification as the third known interstellar comet.
- Observations by James Webb indicate coma rich in carbon dioxide, eight times higher than water vapor.
- Core estimated to be between 320 meters and 5.6 km in diameter suggests formation in distant star system.
- Antisolar coda, with jets of particles aimed at the Sun, changes the center of luminosity by up to 20%.
Variations observed in brightness and position
Astronomers recorded fluctuations in the brightness of comet 3I/ATLAS, attributed to the ejection of gases and dust. This feature, rare in interstellar objects, affects precise position measurements. Telescopes on the ground and in space integrate data to reduce orbital errors.
The phenomenon of the antisolar coda, pointed against the Sun, distorts trajectory calculations. International observers report deviations of up to 20% in similar objects, which justifies the current mobilization.
Chemical composition revealed by advanced telescopes
James Webb’s spectrometer identified high levels of carbonic anhydride in the comet’s coma. This abundance, eight times greater than water, differs from typical solar comets. The emission of OH 450 million km from the Sun indicates an ancient core, more than seven billion years old.
Computational models confirm the origin in external regions of the Milky Way. The diameter of the core varies between 320 meters and 5.6 km, with initial activity suggesting recent exposure to solar radiation. Preliminary data improves theories about distant planetary formation.
Spectral analyzes point to rare volatiles, such as methane and ammonia, in unusual proportions. These elements test hypotheses about conditions in remote star systems.
The composition reinforces the hyperbolicityfrom orbit, with an entry speed exceeding 210 thousand km/h.
Challenges for international orbital measurements
The release of gases displaces the center of luminosity, complicating 3I/ATLAS tracking. Global teams participate in simulations to standardize astrometric data. A workshop scheduled for November 10th brings together technicians to adapt algorithms to hyperbolic trajectories.
Observatories adjust observation protocols in real time. Integrating data from multiple agencies reduces uncertainty in long-term forecasts.
Global Coordinated Observation Campaign
The IAWN organizes exercises from November 27, 2025 to January 27, 2026, focused on the comet. Telescopes in the Hawaiian Islands, Chile and Europe focus efforts on precise measurements.
- Real-time data integration between NASA, ESA and Asian observatories.
- Tests of responses to unexpected orbital deviations.
- Participation of amateurs to validate telescopic observations.
Interstellar origin and future route confirmed
3I/ATLAS follows ‘Oumuamua and 2I/Borisov as third recorded interstellar visitor. Its route passes by Jupiter before leaving the Solar System in 2026, 270 million km from Earth. Continuous monitoring validates rapid detection systems despite safe orbit.
Experts see the event as a test for responses to atypical objects. The hyperbolic trajectory excludes elliptical orbits, confirming an external origin.
The comet offers insights into materials from distant systems, with data that refine models of stellar evolution. Observations will persist until you leave, contributing to planetary databases.
Technical partnerships strengthened by NASA
The agency considers 3I/ATLAS an opportunity to study remote interstellar samples. Partnerships in astrometry advance with lessons from missions like DART. Technicians collaborate on model refinements for external planetary formation.
Exercises prepare agencies for scenarios with irregular objects. The cooperation includes European and Asian agencies, focusing on the integration of ground-based and space telescopes. Collected data improves predictions for similar future events.