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MeerKAT’s First Radio Detection From Interstellar 3I/ATLAS Backs Cometary Origin

An OH absorption signal measured on October 24 points to water outgassing, reinforcing scientific consensus that the visitor is a natural comet.

Overview

  • Astronomers using South Africa’s MeerKAT array reported OH absorption from 3I/ATLAS on October 24 after two September non-detections, marking the first radio detection of the object.
  • The signal matches hydroxyl created when sunlight breaks apart water vapor in a comet’s coma, indicating natural outgassing rather than a technological transmission.
  • After perihelion, telescopes have captured an active coma with long ion and anti-tail structures and unusual chemistry including elevated carbon dioxide and notable nickel signatures.
  • New images this week show the nucleus still intact despite breakup speculation, and most researchers describe the behavior as consistent with a highly active but natural interstellar comet.
  • Observers expect a safe flyby around December 19 at roughly 170 million miles and are coordinating further studies, with potential Juno observations near Jupiter in March 2026.