By SpaceEyeNews .
Astronomy is buzzing with a major breakthrough: the Gemini South telescope has captured the strange anti-solar tail of interstellar object 3I/ATLAS. This faint, teardrop-shaped plume stretches tens of thousands of kilometers into space and is composed mostly of carbon dioxide, not water.
Adding to the mystery, scientists have detected nickel without iron in its gas outflow—something never seen in natural comets. With its massive 46-kilometer nucleus, unusual trajectory, and early activity, 3I/ATLAS is one of the most fascinating interstellar discoveries to date.
Gemini Telescope Confirms Anti-Solar Tail
On August 27, 2025, the 8.2-meter Gemini South Telescope in Chile, equipped with the Gemini Multi-Object Spectrograph (GMOS), observed 3I/ATLAS in detail. What it revealed was extraordinary: a 56,400-kilometer-long anti-solar tail pointing away from the Sun and a coma 18,800 kilometers wide.
The images, captured across four bands (u at 0.365 µm, g at 0.467 µm, r at 0.616 µm, i at 0.747 µm), showed that the tail was not a chaotic dust cloud but a neatly sculpted teardrop structure. Scientists believe this shape is controlled by the balance between solar wind pressure and carbon dioxide outflow.
This is now considered the most detailed 3I/ATLAS anti-solar tail Gemini telescope discovery, a finding that instantly set it apart from all previously observed comets.
CO₂ Activity on Interstellar Object 3I/ATLAS
What drives this strange tail is even more unusual. Unlike Solar System comets dominated by water ice, 3I/ATLAS is powered almost entirely by carbon dioxide (CO₂).
Data from NASA’s SPHEREx mission and the James Webb Space Telescope (JWST) show:
- CO₂ outflow: 130 kilograms per second
- H₂O outflow: 6.6 kilograms per second
- CO outflow: 14 kilograms per second
This means water vapor makes up only about 5% of the total mass loss. In other words, 3I/ATLAS is a CO₂-driven comet, unlike anything seen before.
Even more surprising, the object was already active at six astronomical units (AU) from the Sun—where temperatures are far too cold for water sublimation. The activity was first spotted by NASA’s TESS telescope between May 7 and June 2, 2025.
SPHEREx later mapped the CO₂ plume extending 348,000 kilometers from the nucleus, confirming that it is shaped by the balance of solar wind and outgassing pressure.
Nickel Without Iron: An Unprecedented Finding
The Very Large Telescope (VLT) in Chile added another shocking twist. Spectroscopic data revealed significant nickel vapor emissions, but virtually no iron.
This is unprecedented. In every known comet and asteroid, nickel and iron appear together, as both are formed in supernova explosions and remain chemically linked. Finding nickel without iron in 3I/ATLAS breaks this rule.
The nickel outflow was measured at 5 grams per second at 2.8 AU from the Sun. While small compared to CO₂ production, the absence of iron is the real puzzle. Astronomers also detected cyanide (CN) in the plume, making its chemistry even more peculiar.
Some researchers suggest unfamiliar natural chemistry could explain this. Others, including Avi Loeb, note that it resembles nickel refining processes on Earth, such as the nickel carbonyl method—hinting at industrial-like separation.
If this continues as the comet nears the Sun, it would represent the first interstellar object with nickel emission decoupled from iron.
Giant Nucleus and Odd Trajectory
Adding to its unusual profile, 3I/ATLAS is immense. Data from SPHEREx in August 2025 suggest a nucleus or scattering cloud of about 46 kilometers across—a million times more massive than 2I/Borisov.
Astronomers expected to find smaller interstellar bodies first, not a giant. Its size alone makes it stand out.
Even stranger, its trajectory is aligned with the ecliptic plane, the flat disk where planets orbit. Interstellar objects should arrive from random directions, so this alignment is highly peculiar.
These factors—its massive size, odd trajectory, and bizarre chemistry—make 3I/ATLAS one of the most important objects ever studied.
What Happens Next
The object will reach perihelion on October 29, 2025, its closest approach to the Sun. As it heats up, scientists expect stronger outgassing, possibly exposing new clues.
This period is critical: the enhanced stress could reveal whether its tail and chemical signatures come from natural processes or something else entirely.
Juno Spacecraft Could Join the Mission
NASA scientists are considering a bold maneuver to redirect the Juno spacecraft, currently orbiting Jupiter, toward 3I/ATLAS.
- Proposed maneuver: September 9–14, 2025
- Flyby date: March 14–16, 2026
- Closest approach: ~25 million kilometers
If approved, Juno could use its near-infrared spectrometer, magnetometer, and microwave radiometer to gather direct data. This would be humanity’s first spacecraft flyby of an interstellar object.
Why the Gemini 3I/ATLAS Anti-Solar Tail Discovery Matters
The 3I/ATLAS anti-solar tail Gemini telescope discovery combines several extraordinary findings:
- A teardrop-shaped anti-solar tail 56,400 km long.
- CO₂-driven activity at 130 kg/s, with water at only 6.6 kg/s.
- Nickel without iron, unlike any natural comet.
- A 46 km nucleus, far larger than expected.
- Early activity at six AU, confirmed by TESS.
- A trajectory aligned with the ecliptic plane, not random.
Each factor challenges cometary science. Together, they create one of the most unusual and fascinating mysteries in astronomy.
Conclusion: Awaiting the Truth
As 3I/ATLAS nears the Sun, global observatories—including Gemini, JWST, SPHEREx, and VLT—are preparing for a flood of data. If Juno joins the mission, we may get humanity’s first close-up view of an interstellar visitor.
Whether natural or industrial-like in origin, 3I/ATLAS has already rewritten what we know about interstellar objects. Its anti-solar tail, peculiar chemistry, and massive size make it one of the most important discoveries of modern astronomy.
Stay tuned to SpaceEyeNews for the latest updates as this extraordinary cosmic mystery unfolds.y unfolds.
References:
https://avi-loeb.medium.com/detection-of-an-anti-solar-tail-for-3i-atlas-0b80eb529ead