Interstellar Comet 3I/ATLAS Shows Rare Wobbling Jets in Sun-Facing Anti-Tail

Interstellar comet 3I/ATLAS, though now moving away from Earth and leaving the solar system, continues to intrigue astronomers with unusual activity. New research shows that jet structures in its rare sun-facing “anti-tail,” stretching up to 620,000 miles (1 million km), were wobbling every 7 hours and 45 minutes as the comet approached the sun. Unlike typical comet tails that point away from the sun, an anti-tail faces the star. The wobbling jets reveal that the comet's icy core rotates once every 15 hours and 30 minutes, providing scientists a rare chance to study the physical behavior of a pristine interstellar object formed in another planetary system.

Interstellar Comet 3I/ATLAS Shows Wobbling Jets and Evolving Tail in First Detailed Observations

According to a report published on arXiv, 3I/ATLAS was monitored on 37 nights from July 2 to September 5, 2025, with the Two-meter Twin Telescope at Teide Observatory in the Canary Islands by researchers. Observations traced the evolution of the coma from a sun-facing dust fan into a pronounced antisolar tail as the comet neared the sun on October 30, 2025, at about 130 million miles (210 million km).

The wobbling jet structure was noted on seven nights in August, marking the first time such outgassing has been studied in an interstellar comet.

Interstellar Comet 3I/ATLAS Offers Insights with Anti-Tail and Rotating Jets During Earth Flyby
3I/ATLAS, the third interstellar object known to pass through our solar system, made its closest approach to Earth at around 168 million miles (270 million km) on December 19, 2025. As it makes its way toward the outer solar system, this comet's peculiar anti-tail and rotating jets will tell us still more about the physics of interstellar comets and planet formation in faraway planetary systems.