Lemmon and SWAN set for Oct 21 close approach as Orionids peak

Comet C/2025 A6 Lemmon is brightening rapidly and is expected to make a close pass of Earth around Oct. 21, creating a rare double spectacle with a second comet, C/2025 R2 SWAN, and the peak of the Orionid meteor shower. Both comets are currently visible in binoculars from the Northern Hemisphere and could reach naked eye visibility for observers under dark skies around the third week of October.

Lemmon, discovered on Jan. 3, 2025, by the Mount Lemmon Survey in Arizona, has increased in apparent brightness from magnitude 21.5 at discovery to roughly magnitude 5 or 6 in recent weeks, according to observing databases and astronomers tracking the object. The comet’s activity is driven by solar heating as it approaches perihelion, causing ices to sublimate and form a glowing coma and tail that reflect sunlight. Observers report a bluish or greenish tint to the tail, produced by ionized gases and dust. Orbital calculations put Lemmon’s closest approach to Earth near Oct. 21, with estimates of the distance ranging from about 55 million to 63 million miles 90 million to 102 million kilometers as updated observations refine its path.

SWAN, discovered in September by an amateur who...