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Interstellar Comet 3I/ATLAS Makes Closest Pass to Earth at About 168 Million Miles

Scientists describe the rare interstellar visitor as a natural, volatile‑driven comet posing no risk.

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The XMM-Newton observatory spotted a red X-ray glow around the interstellar comet on December 3.
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Overview

  • Closest approach occurred around 1 a.m. ET on December 19 at roughly 168–170 million miles from Earth, more than 700 times the Earth–Moon distance.
  • The comet is not visible to the naked eye; observers using telescopes or strong binoculars can look pre‑dawn beneath Regulus in the constellation Leo.
  • The Virtual Telescope Project plans a free livestream at 11 p.m. ET on December 19 after weather delayed an earlier broadcast.
  • A multi‑mission campaign spanning Hubble, JWST, SPHEREx, Psyche, MRO, MAVEN, Perseverance, Lucy and solar observatories has returned extensive images and spectra.
  • Hubble measurements estimate an icy nucleus about 1,400 feet to 3.5 miles wide, and trajectory models show a hyperbolic path that will take it past Jupiter in 2026 before it exits the solar system.