It is already one of the most intriguing stories of the night sky so far this century: comet 3I/ATLAS, officially C/2025 N1 (ATLAS). It is about an object that passes through our solar system and that has been captured by telescopes with a striking characteristic: a large jet of gas and dust directed toward the Sun.
3I/ATLAS was discovered on July 1, 2025 by the ATLAS system in Chile and at that time became the third confirmed interstellar object that our solar system passes through (after 2I/Borisov and ʻOumuamua).
It measures between 5 and 11 kilometers in diameter, making it possibly the largest of the interesting objects observed so far. And also the fastest, exceeding 200,000 km/h. Its size and speed make it unique in its species, but there is also another element: its tail, a jet of dust and gas, is headed towards the Sun, something never seen before. And it is not an activity of minutes or caused by its proximity to our star. It’s something constant. And now we have new images to prove it.
These are photographs taken by the Teide Observatory in which A dark nucleus is seen surrounded by a luminous coma, and a “fan” or jet directed towards the Sun.
In comets, Typically, gas and dust escape from the core as it heats up as it approaches the Sun.generating the typical tail that points in the opposite direction to the Sun.
The most reasonable explanation would have to do with temperature. When an area of the comet becomes hotter than its surroundings, the internal ice sublimates strongly in a preferred direction, creating a jet that can point at the Sun by the combination of core rotationlighting geometry and the shape of the exhaust duct.
“This feature, although visually spectacular, does not suggest an artificial object, as some have speculatedbut rather an intense cometary activity that we could expect (although not as pronounced) in an interesting object,” says Miquel Serra.‑Ricart, from the Teide Observatory.
Now, if we are to be precise, there are other known cases of jets “into the Sun.” One of them is 67P/Churyumov–Gerasimenko (the one studied by the Rosetta probe). During the ESA mission, The Rosetta probe observed several jets that apparently pointed towards the Sun. In reality, these originated in cavities or fractures in the ground that, when heated, released gas in complex directions. At certain phases of the comet’s rotation, the jet turned out to be temporarily directed toward the Sun, but this was a geometric illusion rather than a sustained orientation.
Another case is C/2020 F3, better known as NEOWISE. In 2020, this bright comet showed a “jet sunward” (towards the Sun) visible in long exposure photographs. Lowell Observatory astronomers explained that These types of jets may be due to core rotation combined with a localized hot spot.. As the comet spins, that point “throws” material in different directions, and for part of the spin, the orientation coincides with the solar direction.
And finally, we have Halley’s Comet. During the observations of the Giotto and Vega probes (1986), jets towards the Sun were observed. In this case, the cause was a localized ventilation effect: areas of the core covered by a crust of dust that burst open, releasing pressurized gas.
Why is 3I/ATLAS different? In previous cases, the phenomenon lasted hours or days and was local. In 3I/ATLAS, however, the jet sunward seems stable, sustained and of great extension, as if an entire strip of the comet were active. That is, it is not a simple orientation by rotation, at the same time it indicates that there is a large area of the comet that, when heated, releases gas continuously in the solar direction.
And, most intriguingly, this activity is occurring in an interstellar object that has never before been close to the Sun. The comet will reach its perihelion (the closest point to the Sun) at around October 29, 2025, which will imply an increase in activity, possible intensification of the jet and expansion of its dust tail. Astronomers hope to follow it closely to see how they respond to solar heat and what volatiles emerge.