A visitor from another world passes through our cosmic neighborhood. Coming from the depths of space beyond the solar system, interstellar comet 3I/ATLAS challenges our imagination of what comes from the cosmos. These comets are extraordinary: if all the bodies in the solar system share a common origin, Interstellar comets are truly unknown, carrying clues to the formation of very distant worlds.
3I/ATLAS (C/2025 N1) This is the third confirmed object from outside the solar system. It was discovered on July 1, 2025 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) network in Chile. Its study makes it possible to observe matter formed in another star system.
The comet has a core estimated between 10 and 30 kilometers in diameter and moving at more than 68 km/s (approximately 245,000 km/h). Its orbit is hyperbolic, which means that it does not belong to the solar system and that it will continue its journey towards interstellar space after this brief passage in our region.
Her The Sun’s most intense approach took place on October 29, when it was 203 million kilometers from our star. Previously, on October 3, it passed 29 million kilometers from Mars, leaving valuable data for astronomers.
His passage on Earth
It will be this Friday, December 19 when 3I/ATLAS reaches its the closest proximity to Earthapproximately 270 million kilometers, or 1.8 times the distance between the Earth and the Sun. During this approach, it will be on the other side of the Sun, so it will not represent any danger for our planet or for the rest of the bodies in the solar system.
The comet has been the subject of worldwide observations. ESA’s Planetary Defense Office is tracking its trajectory, while astronomers from Hawaii, Chile and Australia contribute to its monitoring. Also searched proof of its presence in old data, a process known as pre-fetchingand data from the ExoMars Trace Gas Orbiter was used to increase the accuracy of its predicted location tenfold.
The director of the European Space Agency (ESA), Josef Aschbacher denied comet speculation: “They’re not aliens, that’s not what some theories believe. It’s a comet that’s moving at very high speed and passing through our solar system. We’ve measured it, we’re observing it, and we know very well what’s happening.”
Even the explorer of the icy moons of Jupiter (Juice) captured recent images from 3I/ATLAS, showing what’s breaking off and helping scientists understand how comets move at extreme speeds through the universe.
The behavior of the interstellar comet which reveals the secrets of the universe
3I/ATLAS is an active comet that provides a unique window into the behavior of these celestial bodies. The first observations made in early August with the Hubble Space Telescope (NASA/ESA) captured a column of dust ejected from the face of the comet heated by the Sun, as well as signs of a dust tail breaking away from its nucleus. This behavior is similar to that of comets originating from our solar system.
As 3I/ATLAS approached the Sun, it lost mass: frozen gases were transformed into steamcarrying dust and ice into space. Subsequent observations, made in late August with the James Webb Space Telescope (NASA/ESA/CSA), revealed the release of carbon dioxide, water, carbon monoxide, carbonyl sulfide, and water ice, confirming that solar heat intensely activates the comet and generates its characteristic coma and tail.
Due to its high speed, ESA has ruled out the possibility of sending a probe or landing on 3I/ATLAS. However, following the experience of the Rosetta mission — which landed on comet 67P in 2014 — the European agency is developing the Comet Interceptor mission, intended to study comets in the outermost regions of the solar system. This mission will allow us to analyze the intact matter from the dawn of the solar system, and although it is very unlikely, it could also study an interstellar comet in the future.
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