Overview
- The two long‑period comets reached their nearest distances around Oct. 20–21, with Lemmon about 55–56 million miles away and SWAN roughly 24–25 million miles away.
- Both are best seen from mid‑northern latitudes about 60–90 minutes after sunset, with Lemmon low in the northwest near Arcturus and the Big Dipper and SWAN in the southwest below Altair.
- Observers report brightness near magnitude +5, often requiring binoculars; Lemmon offered a brief pre‑dawn view on Oct. 21 and both remain near peak brightness through midweek before moonlight grows.
- Lemmon was first identified on Jan. 3, 2025 by the Mount Lemmon Survey, while SWAN was discovered in September by SOHO’s SWAN instrument, drawing extensive public outreach and livestreams.
- The comets’ bluish‑green comae arise from gases released as their ices sublimate, with viewing coinciding with the modest Orionid meteor shower peak of about 20 meteors per hour.