The interstellar comet 3I/ATLAS, originating from outside our Solar System, is currently making its closest approach to Earth. Today, this comet, which has a nucleus measuring between 10 and 30 kilometers and travels at a speed of 68 kilometers per second, is approximately 270 million kilometers away from our planet. This distance poses no threat to Earth.
After its closest approach, 3I/ATLAS will continue its journey through space, reaching its perihelion, the point where it is nearest to the Sun, at about 210 million kilometers from the star, close to the orbit of Mars. It is at this point that the comet is expected to exhibit its greatest activity and brightness, making it observable with professional telescopes. This opportunity to observe the comet with advanced instruments marks the passage of 3I/ATLAS as an “exceptional” scientific event, enhancing our understanding of the origins of the Universe.
Spain is set to play an active role in the study and observation of this comet, as noted by the Ministry of Science, Innovation, and Universities. Their participation is seen as a reinforcement of the country”s position in international astronomical research.
Discovered on July 1, 2025, by the ATLAS (Asteroid Terrestrial-impact Last Alert System) network in Chile, 3I/ATLAS is the third confirmed object from outside the Solar System. Its study provides insights into material formed in another stellar system, which can help scientists learn about the conditions that existed in different parts of the galaxy. The Ministry highlighted that only two other interstellar visitors have been identified previously: “Oumuamua in 2017 and 2I/Borisov in 2019.
A recent update from NASA indicates that the comet has brightened unexpectedly as it passed behind the Sun. The tracking of 3I/ATLAS is the result of significant international collaboration involving the European Space Agency (ESA), NASA, and the International Asteroid Warning Network (IAWN), which includes several Spanish observatories such as the Instituto de Astrofísica de Canarias (IAC), the Montsec Astronomical Park, and others.
The IAWN, coordinated by the United Nations, has organized a global observation campaign from November 25, 2025, to January 27, 2026, with Spain actively participating through the Spanish Space Agency (AEE) and various national centers. The IAC will play a crucial role, utilizing several of its major telescopes from the Teide and Roque de los Muchachos observatories to confirm the comet”s orbit, characterize it, analyze its composition, and measure its activity. Collaboration with Complutense University of Madrid will aid in interpreting spectral data.
Studying the spectrum and dynamics of this comet will provide insights into its age, chemical composition, and possible galactic origin. Preliminary estimates suggest it may have originated from a stellar system formed billions of years before our Solar System. Researching such comets is vital, as they contain primordial material from other stellar systems, formed even before our Sun, and their analysis can offer clues about the processes of planet and star formation across the galaxy.
NASA data reveal that the orbit of 3I/ATLAS does not follow a closed trajectory around the Sun, and historical tracking of the comet shows it is indeed from outside the Solar System.
