The interstellar comet 3I/ATLAS is making its closest approach to Earth today, traveling at a speed of 68 kilometers per second. With a nucleus estimated to be between 10 and 30 kilometers in diameter, this comet, which originated outside our Solar System, will pass at a distance of approximately 270 million kilometers from our planet. While this distance is considered safe, the comet will reach its perihelion, the point closest to the Sun, at about 210 million kilometers away, near Mars” orbit. At this moment, it is expected to exhibit increased activity and brightness, making it an excellent target for professional telescopes.
The opportunity to observe 3I/ATLAS is deemed a significant scientific event, as it offers insights into materials formed in other stellar systems. Spain”s participation in studying this comet has been emphasized by the Ministry of Science, Innovation, and Universities, highlighting the country”s growing role in international astronomical research.
Controversial astrophysicist Avi Loeb has proposed an alternative theory, suggesting that 3I/ATLAS may be an extraterrestrial spacecraft and could potentially perform maneuvers to approach Earth.
Discovered on July 1, 2025, by the ATLAS (Asteroid Terrestrial-impact Last Alert System) network in Chile, 3I/ATLAS is recognized as the third confirmed interstellar object to visit our Solar System. Its hyperbolic orbit confirms that it is not part of our Solar System and will soon return to interstellar space. The previous interstellar visitors were Oumuamua in 2017 and 2I/Borisov in 2019.
The monitoring of comet 3I/ATLAS involves a collaborative effort among various international bodies, including the European Space Agency (ESA), NASA, and the International Asteroid Warning Network (IAWN). This global observation campaign, organized by the United Nations, is set to run from November 25, 2025, through January 27, 2026, with active participation from Spain via the Spanish Space Agency (AEE) and several national research institutions.
The Institute of Astrophysics of Canary Islands (IAC) will play a crucial role in this endeavor, utilizing its major telescopes at the Teide and Roque de los Muchachos Observatories to confirm the comet”s orbit and analyze its composition and activity. Collaboration with Complutense University of Madrid will focus on interpreting spectral data, which will help ascertain the comet”s age, chemical makeup, and possible galactic origin.
Preliminary estimates suggest that 3I/ATLAS may originate from a stellar system formed billions of years before our Solar System. The study of such comets is vital, as they contain primordial material from other stellar systems, formed before the Sun itself. Analyzing these materials can provide clues about the formation of planets and stars in diverse regions of the galaxy, enhancing our understanding of the cosmos.
According to NASA, the orbit of 3I/ATLAS does not follow a closed trajectory around the Sun. By tracking its path backward, astronomers have confirmed that the comet indeed comes from outside our Solar System.
