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Interstellar Comet 3I/ATLAS Reaches Perihelion, Out of Earth’s View

With perihelion hidden by solar conjunction, the next decisive data will come from spacecraft and December follow-up.

Overview

  • 3I/ATLAS hit perihelion today at about 11:47 UT roughly 1.4 AU from the Sun, a geometry that leaves it unobservable from Earth until it emerges from the Sun’s glare.
  • NASA says the interstellar comet poses no threat and will not come closer than about 1.8 AU, with its best Earth-based viewing expected after it reappears in early December and around a mid-December closest approach.
  • Teams report unusual pre‑perihelion spectra, including a CO2‑rich coma, cyanide and bright atomic nickel with little or no iron, findings that require post‑conjunction confirmation and peer review.
  • Speculation about artificial origin persists from some researchers who framed perihelion as an “acid test,” but most scientists and agencies characterize 3I/ATLAS as a natural, though unusual, comet based on current evidence.
  • Follow‑ups include spacecraft checks such as ESA’s JUICE view in the coming days and a coordinated International Asteroid Warning Network campaign later this year to refine astrometry and composition.