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Comet Lemmon Makes Oct. 21 Close Pass Under New-Moon Skies

The long‑period visitor is shining near fourth magnitude, making it the year’s brightest comet for northern observers.

Overview

  • The comet C/2025 A6 (Lemmon) reaches its minimum distance from Earth on October 21 at about 89 million kilometers, according to Russian research institutes.
  • New Moon on October 21 removes lunar glare, creating optimal viewing conditions with naked-eye visibility in dark skies and clearer detail through binoculars or small telescopes.
  • Observers reported a brief fade from about magnitude 4.6 to 5.7 followed by a recovery to near 4.5, with specialists expecting roughly magnitude 3.8–4 around the close pass.
  • Best views favor higher northern latitudes above roughly 50°N, with the comet currently under the Big Dipper in Canes Venatici and set to pass near Arcturus by late October.
  • Astronomers note a highly active tail with gas clumps detaching from the nucleus, and they add that an April 16 encounter with Jupiter shortened the comet’s orbit; the object was discovered on January 3, 2025.