Interstellar Comet 3I/ATLAS erupting ice? Everything on the ‘ice volcano’ claim, Hubble’s odd anti-tail and Avi Loeb’s staggering interpretation
Meanwhile, Harvard astrophysicist Avi Loeb published new analyzes of the latest Hubble data and shared his belief in the imaging projects.
Hubble’s new image of Interstellar comet 3I/ATLAS
Hubble observed 3I/ATLAS on November 30, 2025, and captured an unusual “anti-tail,” a teardrop-shaped inner hair extending toward the sun. The glow covers an area of approximately 40,000 km and has an extension towards the sun of approximately 60,000 km.
Avi Loeb’s commentary on Hubble’s new image of Interstellar comet 3I/ATLAS
In his new paper, “New Hubble Space Telescope Image of 3I/ATLAS,” Loeb argues that the November 30 image shows an “anti-tail” extending some 60,000 km toward the sun. He relates this to predictions from his recent paper, which suggested that “a large number of macroscopic, non-volatile objects” may have separated from the comet due to non-gravitational acceleration. According to Loeb, this swarm should appear “about 60,000 km closer to the Sun than the core,” in accordance with the observed extension.
The ‘ice volcanoes’ of 3I/ATLAS?
A preprint by Josep M. Trigo-Rodríguez and colleagues argues that 3I/ATLAS may exhibit cryovolcanism, based on spiral-like jets seen in high-resolution images as the comet approaches perihelion. The team suggests that heating CO₂ ice could trigger chemical reactions that release gas and energy, producing eruptions that resemble “ice volcanoes.”
The study remains unexamined, and astronomers emphasize that upcoming Hubble, JWST and JUICE spectroscopy will be crucial to test whether these jets require cryovolcanoes or can be explained by normal comet activity.
Where is 3I/ATLAS now?
As of December 5, 3I/ATLAS is approximately 286 million km from Earth, magnitude ~12, and moving from Virgo to Leo. Experienced observers with 12-inch telescopes can see it near Regulus in mid-December. It will remain a faint telescopic target before returning to deep space.
What is 3I/ATLAS?
Discovered by the ATLAS survey telescope in Chile in July this year, 3I/ATLAS (C/2025 N1) is the third confirmed interstellar object ever observed, after ‘Oumuamua and Borisov. It follows a strongly hyperbolic orbit and will leave the Solar System forever.
Scientists now agree on a few key things:
- It has an interstellar origin with an incident velocity of ~58 km/s.
- Hubble suggests that the core is less than 1 km across; but the hair color obscures the actual size of the core.
- JWST and ground-based telescopes detect CO₂, water ice, CO, carbonyl sulfide, cyanide and nickel vapor.
- It passed perihelion at ~1.36 AU in late October and poses no threat to Earth.
- As of the beginning of December, this situation is at magnitude 12 in Virgo.
