BY:SpaceEyeNews.
The 3I ATLAS interstellar comet has shifted from a faint curiosity into one of the most exciting objects in the sky. New images from NASA and the European Space Agency (ESA) show this visitor brightening, venting gas and dust, and growing more active as it heads toward its closest pass by Earth on December 19. At that point, it will still be about 170 million miles (270 million kilometers) away. That is roughly twice the distance between Earth and the Sun.
This is only the third confirmed interstellar object ever found in our Solar System, after ‘Oumuamua and 2I/Borisov. That alone makes it special. The latest data suggest that 3I/ATLAS is not just passing quietly. It is reacting strongly to sunlight. Its structure, chemistry, and behavior now give scientists rare insight into how other planetary systems form and evolve.
3I ATLAS interstellar comet: a rare galactic visitor
The 3I ATLAS interstellar comet was discovered on July 1, 2025, by the ATLAS survey in Chile. At first, astronomers were not certain whether they were looking at an asteroid or a comet. Follow-up images soon revealed a faint coma. That faint glow showed that it was releasing gas and dust rather than remaining a bare rock. The object received the dual designation 3I/ATLAS and C/2025 N1 (ATLAS), marking it as the third known interstellar object.
Unlike typical comets, which loop around the Sun on closed orbits, 3I/ATLAS follows a hyperbolic trajectory. That orbital shape tells scientists it is not bound to our star. It came from outside the Solar System and will leave it again, never to return. Precise tracking shows that it is racing through space at roughly 130,000 miles per hour (about 210,000 km/h).
The comet has already brushed past Mars and made its closest approach to the Sun at the end of October 2025. During these encounters, sunlight began to heat its surface. As with other comets, that energy triggered sublimation—frozen material turning directly into gas and streaming into space. What makes this case different is not the process itself, but the environment where this material formed. The ices and dust assembled around another star, in another protoplanetary disk, under conditions we can only infer.
Estimates from Hubble, JWST, and large ground telescopes suggest the nucleus of 3I/ATLAS measures between 440 meters and 5.6 kilometers across. That wide range comes from the difficulty of seeing the solid core inside a bright coma. Even the lower bound makes it a substantial object. Some studies suggest it could weigh hundreds of millions of metric tons, placing it among the most massive interstellar bodies yet observed.
For astronomers, that combination—interstellar origin, significant size, and clear activity—means this comet is more than a curiosity. It is a sample of another planetary system temporarily drifting through ours.
New NASA images show 3I ATLAS interstellar comet waking up
Hubble’s November 30 snapshot
In late November, NASA and ESA released a striking new image of the 3I ATLAS interstellar comet taken by the Hubble Space Telescope. Captured on November 30, 2025, the view shows a bright central nucleus wrapped in a glowing coma of gas and dust. In the background, the stars appear as long streaks. That effect happens because Hubble tracked the fast-moving comet itself, allowing the stars to blur as the camera followed 3I/ATLAS.
At the time of this observation, Hubble was about 178 million miles (286 million kilometers) from the comet. This distance is significantly closer than during its first look in July, when 3I/ATLAS appeared as a faint smudge with barely any visible structure. The new image reveals a more defined coma and hints of jet activity. Some regions look slightly brighter, possibly where gas flows more strongly from the sunlit side.
Compared with the earlier blur, the November image makes it clear that the comet has “switched on.” As it neared the Sun and warmed, its ices began to release large amounts of gas and dust. The coma expanded. The brightness increased. 3I/ATLAS took on the familiar look of a classic active comet.
Tracking a fast-moving interstellar object
Hubble’s view is more than a beautiful picture. The shape and brightness of the coma allow astronomers to estimate the rate at which 3I/ATLAS is ejecting material. In earlier months, studies suggested that the coma contained a mixture of relatively large dust grains and irradiated organics. In some ways that mixture resembles the material seen in distant bodies beyond Neptune in our own system.
By comparing the new image with earlier ones, scientists can see how quickly the coma expands and whether the activity is steady or variable. Because 3I/ATLAS moves so fast across the sky, it poses a technical challenge. Telescopes must track it accurately to avoid blurring. If tracking is off, small features simply vanish. The successful Hubble observations show that even a rapidly moving interstellar visitor can be studied in detail when the timing and planning are precise.
These updated images also feed into models of the comet’s rotation and structure. Researchers can test ideas about how jets are arranged on the surface. As more data arrive, they can link visible emissions to what lies hidden inside the nucleus.
ESA’s Juice spacecraft captures plasma and dust tails
Juice’s unique vantage point
While Hubble watched from near Earth, ESA’s Jupiter Icy Moons Explorer (Juice) offered a much closer perspective. During November 2025, as Juice cruised toward its future mission around Jupiter, mission controllers turned several instruments toward the 3I ATLAS interstellar comet.
From a distance of only 41 million miles (66 million kilometers), Juice’s Navigation Camera (NavCam) snapped images that revealed a bright coma and hints of two distinct tails. One tail, made of ionized gas, appears to extend more directly away from the Sun as a plasma tail. The other, fainter structure is a dust tail formed by tiny solid particles pushed back by sunlight along a slightly different path.
These early NavCam images were never designed as the main science product. The camera’s primary job is navigation. Even so, the pictures show clear evidence of activity. They also complement the more detailed data collected by Juice’s science instruments. ESA reports that five instruments observed the comet during this campaign. They gathered information about composition, dust distribution, and interaction with the solar wind.
Waiting for the full Juice dataset
There is a twist. Juice is currently using its main high-gain antenna as a heat shield while it passes relatively close to the Sun. Because of that configuration, the spacecraft must rely on a smaller, less efficient antenna to send data back to Earth. The full science dataset from November’s observations will not arrive until February 2026. For now, scientists and the public have only the teaser NavCam image and a few early results.
Even this limited view is important. It confirms that the 3I ATLAS interstellar comet is not just active near the Sun, but also highly responsive to the surrounding plasma environment. The presence of a strong plasma tail suggests that ionized gas streaming from the comet is being shaped by the solar wind. Meanwhile, the dust tail reveals how solid particles drift away more slowly and trace the comet’s path.
Together, Hubble’s distant perspective and Juice’s closer look build a three-dimensional picture of the comet’s environment. They show that 3I/ATLAS is active and that its released material interacts in complex ways with the Sun’s radiation and magnetic field.
What JWST and other telescopes reveal about its strange chemistry
A carbon dioxide–rich comet
Before the recent imaging campaign, the James Webb Space Telescope (JWST) observed the 3I ATLAS interstellar comet with its NIRSpec instrument. These spectra revealed something unusual. The coma is dominated by carbon dioxide (CO₂), with only relatively small amounts of water vapor. The measured CO₂/H₂O ratio is about 8, which is one of the highest ever seen in a comet. It sits far above the trend for typical long-period and Jupiter-family comets.
This extreme ratio suggests that 3I/ATLAS formed in a region where CO₂ ice was abundant. It may have assembled near the “CO₂ ice line” in its original protoplanetary disk. Another possibility is that it formed in a zone exposed to stronger radiation than the outer Solar System. JWST also detected carbon monoxide (CO), water ice, carbonyl sulfide (OCS), and dust. Together, these measurements paint a picture of a chemically rich but unusual comet.
Possible “ice volcanoes” and a processed crust
Ground-based observations and detailed analyses have led some researchers to describe the activity on 3I/ATLAS as similar to cryovolcanism, sometimes called “ice volcanoes.” Jets of gas and dust appear to erupt from specific regions. These outflows likely come from internal pressure or structural weaknesses that allow subsurface ices to escape. A recent study notes that this behavior resembles certain trans-Neptunian objects, icy bodies orbiting beyond Neptune, even though 3I/ATLAS clearly comes from another star system.
The comet likely carries reactive metals and sulfides similar to those found in early meteorites known as carbonaceous chondrites. These materials may have played a role in the early chemistry of planets like Earth. Size estimates ranging from 440 meters to 5.6 kilometers, combined with mass estimates of over 600 million metric tons, suggest a large reservoir of such ancient material.
Scientists suspect that during its long journey through interstellar space, the outer layers of 3I/ATLAS were extensively processed by galactic cosmic rays. Over millions or billions of years, high-energy particles can alter ices and organic compounds. They can build a dark, chemically transformed crust. When the comet approaches a new star and heats up, that crust cracks and vents, exposing fresh material beneath. The CO₂-rich coma and active jets may be the visible signature of that deep history.
All of this makes 3I/ATLAS a natural experiment in how interstellar radiation, chemistry, and stellar heating combine to shape an object over cosmic time.
Why 3I ATLAS interstellar comet matters for science
The 3I ATLAS interstellar comet offers something that even the best telescopes do not usually provide. It is a piece of another planetary system passing directly through our observational range. Every spectrum, image, and light curve measured now helps fill a gap in our understanding of how other systems form planets, comets, and smaller icy bodies.
Because 3I/ATLAS behaves both like and unlike familiar comets, it is especially valuable for comparative planetology. On one hand, it has a coma, tails, and outgassing driven by sunlight, just as Solar System comets do. On the other hand, its composition, activity patterns, and long interstellar journey set it apart. Comparing these similarities and differences helps astronomers refine theories about where different ices condense, how complex organics evolve, and how materials move within and between planetary systems.
The coordinated observation campaign is also a preview of how the scientific community may study future interstellar objects. In the case of 3I/ATLAS, data come from Hubble, JWST, Juice, Mars orbiters, large ground-based telescopes, and advanced amateur setups. ESA notes that Juice used five instruments in November. NASA highlights that spacecraft throughout the Solar System have turned their sensors toward this comet.
As more interstellar objects are discovered, this multi-platform approach will likely become the standard. It allows researchers to build detailed, time-resolved portraits that combine chemistry, structure, and dynamics. In the case of 3I/ATLAS, that portrait includes gas production rates, dust composition, coma shape, and tail behavior. All of these change as the comet moves along its hyperbolic path.
Just as important, this is a time-limited opportunity. Once 3I/ATLAS passes its closest approach in December and continues outward, it will fade. Eventually, it will become too faint for most instruments. That urgency motivates teams to observe it now, while it is bright and active, and to prepare for the delayed arrival of Juice’s full dataset in early 2026. The lessons learned from this single comet may influence how future missions are designed, including potential interceptors for upcoming interstellar visitors.
What happens next for this interstellar visitor?
The 3I ATLAS interstellar comet is headed toward its closest approach to Earth on December 19, 2025, when it will pass at about 170 million miles. It will remain far too faint for the unaided eye, but professional observatories and experienced amateurs with larger telescopes are already following its path through the constellation Virgo.
Over the coming weeks, Hubble, JWST, and ground-based facilities will continue to monitor its brightness, coma structure, and tail behavior. JWST has additional observations scheduled around this period. Those data should refine our understanding of the comet’s volatile inventory and dust properties.
Meanwhile, scientists are preparing to receive the full set of Juice data early in 2026. With those measurements, they hope to map the plasma environment around the comet. They also aim to see how its tails respond to changes in the solar wind and to cross-check chemical signatures against what JWST and other instruments have seen.
As 3I/ATLAS recedes into the outer Solar System and then back into deep space, its signal will weaken. Yet the information gathered during this brief encounter will remain. It will live on in archives, models, and future studies. In that sense, the comet will leave behind a scientific legacy long after it has vanished from our skies.
Conclusion: 3I ATLAS interstellar comet and its fleeting message
The 3I ATLAS interstellar comet is more than a temporary visitor. It is a messenger from another star system, carrying chemical and physical clues about worlds we cannot see directly. New images from NASA’s Hubble Space Telescope and ESA’s Juice mission reveal a bright, active comet with a growing coma, plasma and dust tails, and a composition dominated by carbon dioxide.
As it races past on a hyperbolic path, scientists have only one chance to study it in detail. The data collected now—from JWST, Hubble, Juice, and observatories across the globe—will help us compare our own Solar System to others and refine models of how planets and small bodies form. In a short time, 3I/ATLAS will be gone. The insights it offers into the wider galaxy will remain, reminding us that our system is only one of many in a vast and dynamic universe.
Sources Reference List:
LiveScience – “New NASA, ESA images show 3I/ATLAS getting active ahead of its close encounter with Earth” Live Science
ESA – “Comet 3I/ATLAS shows activity in Juice navigation camera (teaser)” esa.int
Cordiner et al. 2025 – “JWST detection of a carbon dioxide dominated gas coma surrounding interstellar object 3I/ATLAS” (ApJ / arXiv:2508.18209) arXiv+1
Maggiolo et al. 2025 – “Interstellar Comet 3I/ATLAS: Evidence for Galactic Cosmic Ray Processing” (arXiv:2510.26308) arXiv+1
Astrobiology.com – “JWST Detection Of A Carbon Dioxide Dominated Gas Coma Surrounding Interstellar Object 3I/ATLAS” astrobiology.com