Summary: Interstellar comet 3I/ATLAS has reappeared in the predawn sky displaying a surprisingly complex, rapidly changing tail with multiple plumes and an antitail. European amateurs and photographers recorded these features under challenging conditions; astrometry indicates the object remains on its predicted orbit with residuals better than 1 arc second. Harvard astronomer Avi Loeb noted the mass loss appears larger than solar heating alone explains and suggested either fragmentation or, more speculatively, engineered thrusters as possible explanations. JUICE will observe the comet Nov. 2–25, with data expected in Feb. 2026.
Interstellar Comet 3I/ATLAS Re-emerges with a Rapidly Changing, Multi-Plumed Tail — Scientists Ponder Unusual Jets
Summary: Interstellar comet 3I/ATLAS has reappeared in the predawn sky displaying a surprisingly complex, rapidly changing tail with multiple plumes and an antitail. European amateurs and photographers recorded these features under challenging conditions; astrometry indicates the object remains on its predicted orbit with residuals better than 1 arc second. Harvard astronomer Avi Loeb noted the mass loss appears larger than solar heating alone explains and suggested either fragmentation or, more speculatively, engineered thrusters as possible explanations. JUICE will observe the comet Nov. 2–25, with data expected in Feb. 2026.
09:54 PM, 11/11/2025Science
3I/ATLAS returns with an unexpectedly complex, evolving tail
Astronomers and amateur observers are reporting fresh views of the interstellar visitor 3I/ATLAS as it reappears in the predawn sky after passing behind the Sun in late October. Photos show an unexpectedly intricate tail that appears to change on short timescales, renewing interest in the object's origin and activity.
Amateur images reveal multiple plumes and antitail features
On Sunday, Spanish photographers Frank Niebling and Michael Buechner captured images of the comet. Niebling wrote that "Interstellar Comet 3I/ATLAS at 09.11.2025 shows nice tail structures despite interference from moonlight (82% illuminated) and a small height of around 9 to 12 degrees." He noted that the final image was heavily processed to bring out an antitail and a secondary, so-called "smoking" tail.
Observers across Europe have recorded similar fine-scale structures. Austrian amateur Michael Jaeger, who has been tracking 3I/ATLAS since Nov. 4, reported a spray of four or five discrete plumes. "We have something unusual to report," he told SpaceWeather.com. "3I/ATLAS showed a complex tail structure early this morning (Nov. 8)."
Jaeger stressed the challenging observing conditions: during his exposures the comet was only 7–10 degrees above the horizon, and twilight plus bright moonlight reduced visibility. He observed from a mountaintop site and confirmed that astrometry shows the comet remains on its predicted path, with residuals better than 1 arc second. "It hasn't slowed down or released any small spaceships," he added with dry humor.
Rapid changes and competing explanations
Photos taken the same morning by Alberto Quijano Vodniza suggest the tail's appearance can change from day to day, adding to the impression of unusually active, variable jets. The comet appears to be shedding gas and dust at a rate that some researchers say is higher than what solar heating alone would produce.
Avi Loeb (Harvard): "Houston, we have a problem with the natural comet hypothesis!"
Harvard astronomer Avi Loeb highlighted this discrepancy, proposing two possible explanations: the nucleus may have fragmented near the Sun—exposing fresh material and increasing mass loss—or, more speculatively, engineered thrusters could be producing directional jets with a smaller total mass loss. These ideas remain hypotheses and are under active discussion; current tracking shows 3I/ATLAS continues to follow a standard cometary orbit.
Trajectory, encounters and upcoming observations
On Oct. 3 the object passed about 18.6 million miles from Mars and several of the planet's orbiters. NASA has not yet released images from that encounter, citing impacts from the government shutdown. The comet reached perihelion on Oct. 29 at roughly 126 million miles from the Sun and is now receding from the inner solar system. Its closest approach to Earth is expected around Dec. 19 at about 167 million miles.
Between Nov. 2 and Nov. 25, the European Space Agency's Jupiter Icy Moons Explorer (JUICE) will observe 3I/ATLAS and may catch it during a very active phase. JUICE data are expected to be released in February 2026, and those measurements will help researchers better quantify the comet's mass loss and jet behavior.
What to watch next
Continued imaging and astrometry from both amateurs and professional observatories will be crucial. High-cadence monitoring, multiwavelength observations, and forthcoming spacecraft data (including JUICE) should clarify whether the observed activity can be explained by natural fragmentation and outgassing or demands alternative explanations. For now, 3I/ATLAS remains an intriguing, rapidly evolving interstellar visitor worthy of close attention.