Interstellar Comet 3I/ATLAS: Changing Tail Captured in New Images

An unprecedented celestial visitor continues to captivate astronomers as new images reveal dramatic changes to interstellar comet 3I/ATLAS, including a giant jet of material shooting toward the sun. As the comet approaches its closest point to our star on October 29, scientists worldwide are mobilizing unprecedented observation campaigns to study this rare visitor from beyond our solar system.

Breaking New Ground in Interstellar Observation

Recent observations from the Two-meter Twin Telescope (TTT) at Spain's Teide Observatory have revealed a fascinating new development: 3I/ATLAS is projecting a massive, fan-shaped jet of gas and dust directly toward the sun. The composite image, combining 159 separate exposures taken on August 2, shows the comet's icy nucleus surrounded by a glowing coma with a sudden break in its luminous ring marking where the jet originates.

According to Miquel Serra-Ricart, chief science officer at the Light Bridges research institution, this sunward jet is perfectly normal comet behavior. "This is the usual," Serra-Ricart explained. "Jets are pointing to [the] sunward direction and [the] comet's tail in the anti-solar direction." The jet could extend roughly 6,200 miles from the comet's surface and likely contains dust particles and carbon dioxide.

Understanding Comet Anatomy: Jets and Tails

The discovery of this prominent jet provides an excellent opportunity to understand how comets behave. While comets are famous for their glowing tails that can stretch hundreds of millions of miles opposite the sun, jets are smaller structures that can point sunward—a seemingly counterintuitive phenomenon that follows basic physics.

As comets approach the sun, they heat unevenly. The sun-facing side warms fastest, and if a weak spot on the surface heats sufficiently, growing supplies of sublimated gases can blast outward like a geyser, shooting material thousands of miles toward the sun. As the nucleus rotates, this jet takes on the fan shape captured in recent images.

The Tail's Evolution

New images from NASA, not yet publicly released, show the changing tail of 3I/ATLAS as it continues its journey through our solar system. NBC News reported that the comet is currently hidden behind the sun and won't be visible to Earth-based telescopes until it reemerges in early December. This period of solar conjunction makes the current observations particularly valuable.

Global Scientific Coordination Mobilizes

In an unprecedented move, the International Asteroid Warning Network (IAWN)—a United Nations-endorsed group typically focused on potentially hazardous asteroids—has launched a dedicated campaign to monitor 3I/ATLAS. This marks the first time an interstellar object has been targeted by IAWN's observation campaigns.

The network announced a comet campaign running from November 27, 2025, through January 27, 2026, specifically designed to "introduce methods for improving astrometry from comet observations." Harvard Professor Avi Loeb noted that this coordination follows a white paper he submitted to the United Nations advocating for comprehensive study of interstellar objects.

Why This Matters for Planetary Defense

"Comets present unique challenges for accurate astrometric measurements and orbit predictions," IAWN stated in their announcement. The network aims to exercise the observing community's capability to extract accurate astrometry from objects with extended morphological features like comae and tails that can systematically affect measurements.

The Perihelion Opportunity

October 29 represents a critical date when 3I/ATLAS reaches perihelion—its closest approach to the sun at approximately 126 million miles. This proximity creates optimal conditions for scientists to understand the comet's composition.

"Every comet by definition has a close approach to the sun," explained Darryl Seligman, a professor at Michigan State University. "That point is when the comet has the most direct sunlight, so it is at its warmest." This heat causes different ices to activate at various temperatures, providing researchers with "the most holistic view of the comet's composition because the most possible ices should be active."

A Rare Interstellar Visitor

3I/ATLAS holds the distinction of being only the third confirmed interstellar object ever detected in our solar system, following 1I/'Oumuamua in 2017 and 2I/Borisov in 2019. What makes this discovery particularly exciting is its size—somewhere between 3 and 7 miles wide, making it significantly larger than its predecessors while moving faster than both.

"This is only the third such interstellar comet we've ever been able to study, and planetary scientists are super excited to learn about what comets in other solar systems are like," said Jason Wright, director of the Penn State Extraterrestrial Intelligence Center.

Distinctive Characteristics

The comet has displayed several unusual features that have generated significant scientific interest. Its gas plume contains considerably more nickel than iron—a ratio orders of magnitude larger than observed in known comets. Additionally, James Webb Space Telescope observations revealed the comet is wrapped in carbon dioxide fog, and it contains only about 4% water by mass, much less than typical comets.

Despite these peculiarities, scientists maintain that 3I/ATLAS behaves consistently with natural comet activity. "There is clear-cut evidence of cometary activity—it was and still is behaving entirely in line with solar system comets at large distances," Seligman confirmed.

Spacecraft Observation Opportunities

According to research published by Samuel Grant of the Finnish Meteorological Institute, NASA's Europa Clipper spacecraft may encounter charged particles from 3I/ATLAS's ion tail between October 30 and November 6. This represents a rare opportunity to directly sample material from a comet originating beyond our solar system.

"We have virtually no data on the interior of interstellar comets and the star systems that formed them," Grant noted. "Sampling the tail in this way is the closest we can currently get to a direct sample of such an object, and thus a different part of the galaxy."

What Happens Next

As 3I/ATLAS emerges from behind the sun in early December, astronomers will gain a crucial opportunity to observe how the comet changed during its close solar encounter. The extent to which its jet and tail may have grown will provide valuable insights into interstellar comet composition and behavior.

NASA has confirmed that 3I/ATLAS poses no threat to Earth, maintaining a distance of at least 240 million kilometers from our planet. On December 19, 2025, the comet will make its closest approach to Earth, offering another prime observation window.

Looking Forward

The coordinated global effort to study 3I/ATLAS represents a new chapter in interstellar object research. With advanced telescopes like Hubble and James Webb already capturing unprecedented detail, and spacecraft like Europa Clipper potentially sampling its particles, scientists are gathering data that could reshape our understanding of planetary formation in distant star systems.

As Wright observed, the differences between interstellar comets and our solar system's comets "can help tell us about how other star systems form their planets." The coming months will reveal whether 3I/ATLAS holds more surprises as it completes its journey through our cosmic neighborhood before returning to the vast expanse of interstellar space.

For astronomers and space enthusiasts alike, 3I/ATLAS serves as a reminder that our solar system remains open to visitors from the broader galaxy—each carrying clues about the universe beyond our immediate cosmic vicinity.