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Interstellar Comet 3I/ATLAS Brightens and Accelerates as Global Observers Ready for Dec. 19 Flyby

A coordinated, time‑limited campaign now focuses on unexpected brightening with measured non‑gravitational acceleration.

Overview

  • JPL navigation analysis by Davide Farnocchia reports measurable acceleration not explained by gravity following the object’s perihelion passage.
  • Observations show a rapid post‑perihelion brightening with estimates of more than 13% mass loss, yet imaging has not revealed the large gas and dust coma that would typically accompany it.
  • NASA and ESA say there is no impact risk as the one‑time interstellar visitor will pass about 270 million kilometers from Earth on December 19 along a hyperbolic trajectory.
  • A broad observing effort is underway, with Solar Orbiter, SOHO, and Parker Solar Probe collecting data, China’s Tianwen‑1 releasing high‑resolution images, and ESA’s JUICE allocating observation time from November 2 to 25.
  • Spectral reports point to unusually low water and relatively high nickel signatures, while proposals of an artificial origin remain a minority view rejected by major agencies.