Decoding Mysterious Anti-Tail And Tail Jets Emanating From Interstellar Comet 3I/ATLAS

British astronomers Michael Buechner and Frank Niebling shared the latest observations of mysterious interstellar comet 3I/ATLAS on the official site of the British Astronomical Association. "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 a try on comet 3I Atlas," the astronomers wrote.

The astronomers shared a "heavily processed" large-scale image of the space object, captured on November 9, which shows massive anti-tail jets pointing towards the Sun and a longer tail jet extending away from it, Harvard astrophysicist Avi Loeb weighed in on it while writing about it in his blog on Medium.

Also Read | Harvard Physicist Weighs In On Complex Jet Structure On Interstellar Object 3I/ATLAS

The Harvard astrophysicist explained the presence of two distinct jets pointing towards the Sun, with an outer mass density a million times greater than the solar wind.

The anti-tail jets stretch around 0.95 million kilometres towards the Sun. Meanwhile, the tail jet spans an impressive 2.85 million kilometres in the opposite direction. Notably, the longer, collimated jet indicates a highly organised and massive ejection of material.

The findings are remarkable as recent observations showed the comet without a tail after passing close to the Sun. But the tail has appeared now.

"The image shows two anti-tail jets out to 10 arcminutes towards the Sun accompanied by a longer collimated jet, extending away from the Sun out to an angular separation of 30 arcminutes, roughly the diameter of the Sun or the Moon," Loeb wrote in his blog.

Also Read | Interstellar Object 3I/ATLAS Loses Tail, Reignites Debate About Its Origin And Composition

Loeb also explained the mass loss rate, which, according to him, is estimated at 50 billion tonnes per month, suggesting a nucleus diameter of at least 5-10 kilometres.

"Assuming a solid density of 0.5 grams per cubic centimeters, this means that the diameter of 3I/ATLAS must be bigger than 5 kilometers. If it is a natural comet and most of its nucleus survived perihelion, then the diameter of 3I/ATLAS should be 10 kilometers or larger," he added.

Another set of images captured by astro-photographers M Jager, G Rhemann and E Prosperi on November 8, 2025, at 4:10 Universal Time (UT) showed at least seven distinct jets, including anti-tails in the sunward direction.

3I/ATLAS has become a celestial celebrity, and its unusual structure and mass loss rate have sparked speculation about the origin, with some scientists suggesting it could be a piece of advanced interstellar technology.

Astronomers continue to study 3I/ATLAS, awaiting its closest approach to Earth on December 19, 2025. The experts will also look for spectroscopic observations, which will help determine the comet's composition, velocity and mass flux, shedding light on its mysterious nature.