This morning, at 4.10 Universal Time (UT) on November 8, 2025, the interstellar object 3I/ATLAS showed a complex jet structure. M. Jäger, G. Rhemann and E. Prosperi observed 3I/ATLAS at 29 degrees separation from the Sun in the sky, as reported here.
The stacked images, constituting 24 exposures in the green filter— each lasting 35 seconds , 2 exposures in a red filter and 2 exposures in a blue filter, show a large glowing halo extending out to half a million kilometers (5 arcminutes). The images show at least 7 distinct jets, some of which are anti-tails in the sunward direction.
Given that a large number of jets appear in many directions, the reported non-gravitational acceleration of 3I/ATLAS (as discussed here) requires much more than 10–20% of its initial mass to have been ejected near perihelion. Only a fraction of that mass carries an excess momentum in a preferred direction. This means that the cloud of debris around 3I/ATLAS must represent a substantial fraction of its initial mass for a natural comet. However, technological thrusters could give the object a boost with much less mass jetted out at a higher speed.
At the time of observations, 3I/ATLAS was 7–10 degrees above the horizon. Eventually, twilight interfered with the observations, which took place under a bright moonlight.
Is the network of jets associated with pockets of ice on the surface of a natural cometary nucleus or are they coming from a set of jet thrusters used for navigation of a spacecraft? We do not know.
For now, let us enjoy the view. After all, a picture is worth a thousand words.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.