Harvard scientist Avi Loeb has said that interstellar object 3I/ATLAS "still shows an anti-tail" ahead of its closest approach to Earth on December 19 at a safe distance of approximately 270 million kilometres.

This event provides a perfect opportunity for scientists to study this object from another star system.

3I/ATLAS, only the third interstellar object ever detected, following 1I/'Oumuamua and 2I/Borisov, has gained massive attention worldwide for its mysterious nature, with many experts suggesting that it might not be a naturally occurring object. But when NASA shared details, the space agency referred to it as a 'comet'.

Recently, Loeb weighed in on the latest images of the comet taken by Teerasak Thaluang in Rayong, Thailand, on December 13, 2025.

"The rotational-gradient brightness map shows a prominent anti-tail, uncommon for comets, pointing in the direction of the Sun," he wrote in a blog post on Medium.

"Whereas an anti-tail had been seen for solar system comets as a temporary perspective effect when the Earth crossed the comets' orbital plane, this is clearly not the case with 3I/ATLAS."

An anti-tail is a rare phenomenon where a comet's tail appears to point towards the Sun, opposite to the expected direction. 

Source:Ndtv