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Interstellar Comet 3I/ATLAS Reaches Closest Approach to Earth Today

A new analysis using long‑baseline spacecraft astrometry finds a small non‑gravitational acceleration likely caused by outgassing.

Overview

  • The third confirmed interstellar visitor comes closest at roughly 06:00 UTC on December 19 at about 1.8 AU, or ~270 million kilometers, from Earth.
  • The object is too faint for naked‑eye viewing, with pre‑dawn observing favored using medium telescopes under dark skies in the constellation Leo as it moves toward Virgo.
  • Live coverage was scheduled through the night of December 18 into the morning of December 19 via the Virtual Telescope Project, with additional streams available on NASA+.
  • The reported acceleration was derived from precise position measurements using NASA’s Psyche spacecraft and ESA’s Mars Trace Gas Orbiter, consistent with outgassing effects seen in comets.
  • More than 200 facilities, including Hubble, SPHEREx and major ground observatories, have collected images, spectra and astrometry during the object’s brief passage through the inner solar system.