Particle.news
Download on the App Store

Interstellar Comet 3I/ATLAS Shows Dual Tails and Rhythmic Brightening Ahead of Dec. 19 Flyby

Scientists are escalating observations to test early claims of unusual, possibly cryovolcanic activity.

Overview

  • NASA and ESA report the object will make its closest pass on December 19 at roughly 270 million kilometers, traveling near 60 km per second, with no threat to Earth.
  • New Hubble imaging from December 3 and agency analyses reveal two distinct tails—a plasma tail and a fainter dust tail—signaling elevated outgassing.
  • Astronomers have measured a repeating brightness pulse every 16.16 hours tied to jets from the comet’s rotation, with agencies describing a natural process despite outside speculation.
  • A recent arXiv preprint by Josep M. Trigo-Rodríguez, Maria Gritsevich and Jürgen Blum proposes a metal-rich, trans‑Neptunian–like body with possible cryovolcanism and Fischer–Tropsch–type chemistry, a hypothesis that remains unreviewed.
  • The object is only the third confirmed interstellar visitor observed, and a coordinated observing campaign is underway with broader results expected to be shared in February 2026.