Overview
- Comet C/2025 A6 (Lemmon) made its nearest pass on Oct. 21 at about 55–56 million miles, a day after C/2025 R2 (SWAN) approached to roughly 24–25 million miles.
- Lemmon is visible to the naked eye from dark locations at roughly magnitude +4 to +5, while the fainter SWAN is a binocular target.
- Best viewing is about 90 minutes after sunset: look to the northwest near Arcturus and the Big Dipper’s handle for Lemmon, and to the southwest below Altair and the Summer Triangle for SWAN.
- Lemmon was discovered Jan. 3 by the Mount Lemmon Survey and won’t return for roughly 1,150–1,350 years; SWAN was identified Sept. 11 by SOHO’s SWAN instrument and is also a long‑period comet.
- The comets’ bluish‑green glow comes from gas in their comae, and with a new moon and the Orionid meteor peak creating dark skies, astronomers urge viewers to look now as brightness can change and livestreams track updates.