Comet 3I/ATLAS has gone from obscure catalog entry to one of the most closely watched objects in the sky, and the latest images suggest it may be doing something extraordinary. Instead of a smooth, steadily evaporating surface, the interstellar visitor appears to be punctured by erupting “ice volcanoes” that are blasting gas and dust into space in focused jets. That behavior is giving astronomers a rare, three‑dimensional look at how a frozen body from another star system reacts when it dives toward our Sun.
As I follow the data coming in from professional observatories and spacecraft, a picture is emerging of a small, oddly active nucleus wrapped in a carbon dioxide rich shroud and threaded with narrow plumes. Those plumes, likely driven by cryovolcanic vents, are reshaping expectations about what an interstellar comet can look like and how such objects might have formed before they were flung into the void between stars.
Why 3I/ATLAS is such a rare visitor
The first thing to understand about Comet 3I/ATLAS is how unusual it is to see it at all. According to Comet 3I/ATLAS Facts and FAQS, this object is only the third known body to pass through our solar system on a trajectory that marks it as an interstellar visitor, following 1I/ʻOumuamua and 2I/Borisov. It is cataloged as a Comet because it is actively shedding material, and the Stats compiled so far indicate a nucleus roughly 3.5 miles (5.6 kilometers) across, large enough to sustain prolonged outgassing as it approaches the Sun. That combination of clear interstellar origin and substantial size makes 3I/ATLAS a uniquely valuable natural probe of conditions in another planetary system.
Interstellar comets like this one are thought to be fragments ejected during the early, chaotic phases of planet formation around other stars, then left to wander the galaxy for millions or billions of years. When 3I/ATLAS finally crossed into the realm of the planets, its hyperbolic path and high incoming speed immediately marked it as a foreigner, and astronomers began tracking its motion and brightness to pin down its properties. The chance to watch a Comet that formed around another star, then compare its behavior with long‑period comets native to our own Oort Cloud, is central to why 3I/ATLAS has become such a priority target.
Pinning down an interstellar trajectory from Mars
To understand what 3I/ATLAS is doing, researchers first had to know exactly where it was going. That is where a clever bit of geometry involving Mars came in. The European Space Agency reported that by combining observations from Earth with a new viewing angle from Mars data, mission teams were able to refine the comet’s orbit with far greater precision. That “New angle from Mars” effectively turned the Red Planet into a second observatory, letting scientists triangulate the path of 3I/ATLAS and confirm that its trajectory is not bound to the Sun, but instead is consistent with an object that might be an interstellar one.
Those orbital refinements matter for more than just celestial bookkeeping. With a better handle on the comet’s incoming and outgoing path, planetary defense specialists at ESA can test how well their models handle fast, non‑periodic objects, while dynamicists can rewind the motion of 3I/ATLAS to estimate which region of the galaxy it may have come from. The same data also help observers schedule their campaigns, since knowing exactly when and where the Comet will appear in the sky is essential for capturing the high‑resolution images that are now revealing its eruptive surface.
A carbon dioxide rich coma that breaks the mold
Even before the talk of ice volcanoes, 3I/ATLAS was already surprising astronomers with the composition of its surrounding haze. Spectroscopic observations showed that the coma, the diffuse envelope of gas and dust around the nucleus, is dominated by carbon dioxide rather than the water vapor that typically drives activity in many solar system comets. One detailed analysis concluded that 3I/ATLAS’s coma is largely carbon dioxide, a finding that immediately set it apart from most familiar icy bodies. That composition suggests the comet’s surface and near‑surface layers are unusually rich in frozen CO₂, which sublimates at lower temperatures than water ice and can drive activity farther from the Sun.
This carbon dioxide dominance has two important implications. First, it hints that the region of the protoplanetary disk where 3I/ATLAS formed may have had a different balance of volatiles than the zone that produced many of our own comets, perhaps colder or more CO₂ rich. Second, it means that as the Comet approaches the Sun, jets powered by CO₂ sublimation can switch on earlier and in different patterns than water‑driven plumes, potentially explaining some of the unusual structures now seen in the coma. When those jets erupt through localized vents, they can carve out channels and pits that resemble the plumbing of cryovolcanoes, setting the stage for the “ice volcano” interpretation.
New images and the case for “ice volcanoes”
The most dramatic twist in the 3I/ATLAS story comes from a fresh set of high‑resolution images that show the comet’s surface is anything but quiet. A recent study, highlighted in a report that described how 3I/ATLAS might be covered in erupting “ice volcanoes”, points to a series of discrete jets that appear to originate from specific regions on the nucleus rather than from a uniform, sunlit surface. In that account, researchers describe being “all surprised” by how structured the activity looked, with multiple plumes fanning out like geysers instead of a simple, smooth halo of gas. The pattern is consistent with cryovolcanoes, vents where pressurized volatile ices erupt through overlying material.
On icy moons such as Enceladus and Triton, cryovolcanism is driven by internal heat and subsurface reservoirs, but in the case of 3I/ATLAS the energy source is almost certainly sunlight warming volatile rich layers. As the Comet rotates, different patches of its crust are illuminated, and pockets of carbon dioxide and other ices can rapidly sublimate, building pressure until they burst through weak spots. The resulting jets, seen as narrow, bright streaks in the new images, give the impression of a surface riddled with “ice volcanoes,” even if the underlying mechanism is closer to explosive venting than to the lava‑filled cones we associate with terrestrial volcanism.
Live tracking of cryovolcanic eruptions
Those eruptive features are not just static snapshots. Observers following 3I/ATLAS in near real time have watched the jets wax and wane as the comet swings around the Sun. A running science news feed recently noted that a series of cryovolcanoes, sometimes nicknamed “ice volcanoes,” erupted on the surface of Comet 3I/ATLAS, blasting out material locked inside its core. That description matches the evolving images, which show multiple jets turning on and off as the nucleus spins, suggesting that the vents are tied to specific topographic features that rotate in and out of sunlight.
From a physical standpoint, these outbursts are a window into the comet’s interior. Each cryovolcanic plume carries dust grains and ices that were previously shielded from radiation, effectively sampling layers that have not been altered since 3I/ATLAS left its home system. By tracking how the brightness and direction of the jets change over time, researchers can infer the rotation period of the nucleus, the distribution of active regions, and even hints of internal layering. The fact that the cryovolcanoes appear as a “series” rather than a single dominant vent suggests a complex crust with multiple weak zones, perhaps shaped by past heating episodes or collisions.
Jets, spin, and the comet’s evolving shape
The jets on 3I/ATLAS are not just passive exhaust; they can actively reshape the comet’s motion and structure. As gas and dust stream away from the surface, they exert tiny but persistent thrusts that can torque the nucleus, altering its spin rate and axis over time. Observers have already noted that 3I/ATLAS is displaying multiple jets after passing the Sun, with interstellar object 3I/ATLAS showing distinct plumes as it recedes from its closest approach. Its perihelion, the point of closest approach to our star, occurred on October 29, 2025, and the fact that the jets remain active afterward indicates that subsurface volatiles are still being tapped as the comet cools.
Over longer timescales, this kind of jet‑driven evolution can change the shape of the nucleus itself. Regions that host persistent cryovolcanoes may erode into pits and depressions, while less active areas retain their original contours. For 3I/ATLAS, which will not return once it leaves the solar system, the current apparition is the only chance to watch that sculpting in action. By comparing images taken before and after perihelion, astronomers can look for subtle changes in the silhouette of the nucleus and the distribution of dust in the coma, clues to how quickly an interstellar comet can be reshaped by a single close pass to a star.
How 3I/ATLAS compares to other interstellar visitors
To appreciate how strange 3I/ATLAS looks, it helps to set it alongside its predecessors. The first known interstellar object, 1I/ʻOumuamua, never developed a visible coma or tail, leaving scientists to infer its properties from its tumbling light curve and slight non‑gravitational acceleration. The second, 2I/Borisov, behaved more like a conventional comet, with a diffuse coma and tail but without the kind of sharply defined jets now seen on 3I/ATLAS. As one overview of the current object notes, what makes 3I/ATLAS so intriguing is that it combines clear interstellar kinematics with vigorous, structured activity more reminiscent of some of the most dynamic comets in our own system.
That contrast is sharpening debates about how diverse interstellar debris can be. If 1I/ʻOumuamua was a relatively inert shard and 2I/Borisov a more typical icy body, then 3I/ATLAS, with its carbon dioxide rich coma and apparent ice volcanoes, represents a third, more volatile‑laden category. The fact that all three have different behaviors suggests that the processes that eject material from young planetary systems can sample a wide range of compositions and histories. For planetary scientists, each new interstellar Comet is less a one‑off curiosity and more a data point in a growing census of how other systems build and discard their small bodies.
What backyard observers can actually see
While the cryovolcanoes themselves are far too small to resolve with amateur equipment, the overall activity of 3I/ATLAS is accessible to dedicated skywatchers. After swinging around the Sun, the comet has returned to the morning sky, climbing higher before dawn and bright enough for modest telescopes under dark conditions. Practical observing guides explain that Here you can see Comet 3I/ATLAS for yourself, with charts that show its path and notes on how its brightness is evolving. The images they are taking, especially from larger amateur setups, reveal a condensed core and a fan‑shaped tail that hint at the underlying jets, even if the individual vents remain unresolved.
For many observers, the appeal is not just aesthetic but historical. Watching 3I/ATLAS drift against the stars is a chance to see, in real time, an object that spent most of its existence in deep interstellar space. The fact that professional teams are simultaneously capturing detailed images of its “ice volcanoes” adds an extra layer of meaning to those backyard views. When an amateur photographs the comet’s fuzzy glow, they are indirectly recording the combined output of multiple cryovolcanic vents, each one a tiny window into the geology of a world that formed around another star.
What 3I/ATLAS is teaching us about planetary systems
Beyond the spectacle, the scientific payoff from 3I/ATLAS’s activity is substantial. The combination of a carbon dioxide dominated coma, multiple jets, and apparent cryovolcanoes suggests that the comet’s interior preserves a complex layering of ices and dust. By modeling how those layers respond to solar heating, researchers can infer the thermal and chemical environment in which the Comet originally formed. The detailed Stats compiled in the Comet 3I/ATLAS Facts and FAQS entry, including its size and activity level, feed directly into those models, helping to constrain the range of possible birthplaces within a protoplanetary disk.
At the same time, the need to track such a fast, unpredictable visitor has stress‑tested the global observing network. Coordinated campaigns that link Earth‑based telescopes, spacecraft near Mars, and even amateur observers have shown how quickly the astronomical community can pivot when a new interstellar object appears. The lessons learned from 3I/ATLAS, from refining orbits with From Mars data to interpreting exotic cryovolcanic activity, will carry forward to the next visitor that crosses the Sun’s neighborhood. Each time that happens, we gain not just another intriguing Comet, but a sharper, more nuanced picture of how planetary systems, including our own, build and scatter the icy worlds that populate their outskirts.
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