Prepare to have your understanding of comets challenged. A groundbreaking new study on the interstellar object 3I/ATLAS has just been released, and it’s raising more questions than answers. This enigmatic visitor, observed by the Keck II telescope in Hawaii on August 24, 2025, is defying all our expectations about what a comet should be. But here's where it gets controversial: could 3I/ATLAS be hinting at processes we’ve never seen in nature before?
The Keck Cosmic Web Imager (KCWI) captured 3I/ATLAS at a distance of 2.75 and 2.6 astronomical units (AU) from the Sun and Earth, respectively. Much like the Hubble Space Telescope images from July 21, 2025, the Keck data reveals a baffling anti-tail extension pointing toward the Sun—a feature that’s anything but typical for comets. And this is the part most people miss: the spectrum of the gas plume around 3I/ATLAS shows strong nickel emissions but no signs of iron, a combination previously only observed in industrially produced nickel alloys through the carbonyl chemical pathway. Could this process, which involves the formation and decomposition of nickel tetracarbonyl (Ni(CO)4), actually occur naturally near the nucleus of 3I/ATLAS? The authors of the study think so, suggesting that nickel should be highly concentrated near the nucleus as a result.
A closer look at the KCWI images in nickel (Ni) and cyanide (CN) emission reveals another anomaly: nickel is centrally concentrated relative to cyanide, with emission radii of 600 kilometers for nickel and 840 kilometers for cyanide. Even more puzzling, the production rate of nickel relative to cyanide is significantly higher than in the interstellar comet 2I/Borisov and far exceeds the median for solar system comets. The asymmetric emission profiles of both elements, extending both toward and away from the Sun, provide undeniable evidence of an anti-tail—yet the white light image shows no traditional cometary tail, which should be visible if dust were scattering sunlight and being pushed by solar radiation pressure.
These findings further cement 3I/ATLAS as an outlier among comets. With seven previously documented anomalies, I’ve maintained its ranking as 4 on the Loeb scale, a measure of how much an object deviates from known natural phenomena. But the story doesn’t end here. We’re eagerly awaiting the release of images from the HiRISE camera on the Mars Reconnaissance Orbiter, captured on October 2, 2025, when 3I/ATLAS passed within 30 million kilometers of Mars. These images, with a pixel resolution of 30 kilometers, will offer a side view of the glow around 3I/ATLAS—three times sharper than our current best images from Keck and Hubble. Additional data from the Juice spacecraft in November 2025 and the Juno spacecraft in March 2026 will further enrich our understanding.
As we gather more high-quality data, the nature of 3I/ATLAS becomes increasingly intriguing. Science thrives on evidence, not speculation, and this object is a perfect example of how instruments can reveal truths that challenge our assumptions. But here’s the question I leave you with: Could 3I/ATLAS be more than just a peculiar comet? Could it be a sign of processes we’ve never encountered before, perhaps even hinting at something beyond natural explanations? Let’s keep the discussion going—what do you think? Share your thoughts in the comments below.
About the Author:
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s Black Hole Initiative, and director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics. He is the bestselling author of Extraterrestrial: The First Sign of Intelligent Life Beyond Earth and co-author of the textbook Life in the Cosmos. His latest book, Interstellar, explores the mysteries of objects like 3I/ATLAS and the broader implications for our understanding of the universe.
