Two Stunning Comets to Light Up October Skies — Don’t Miss This Rare Cosmic Show

October nights are putting on a breathtaking celestial show, as two bright green comets, Lemmon and SWAN, grace the skies simultaneously—a spectacle not seen in decades. Comet Lemmon (C/2025 A6), the brightest of the pair, is making its closest pass to Earth on October 21, zooming by at around 55 million miles. This comet’s brilliant green glow is visible just after sunset in the northwest, near the constellation Boötes, dazzling astronomers and casual skywatchers alike.​

Not far behind, Comet SWAN (C/2025 R2) is also lighting up the southwestern skies after dusk, though a bit dimmer. Discovered only last September, SWAN is currently visible through binoculars with its blue-green haze hovering low above the horizon near Sagittarius. Both comets are expected to reach peak brightness around the same time as the Orionid meteor shower peak on October 20–21 when the sky will be moon-free and perfectly dark.​

Skywatchers should seize this rare opportunity: two green-hued visitors from the outer solar system putting on a dazzling side-by-side performance. While Lemmon edges closer and shines brighter, SWAN complements the show, creating a visual double-act rarely seen before. Observers far from city lights with binoculars or small telescopes will be treated to an unforgettable cosmic spectacle.

With the added bonus of meteor streaks flashing overhead, October’s night skies invite everyone outside for a celestial event that’s as photogenic as it is fleeting. Don’t miss your chance to catch these green comets together—a pair of cosmic wanderers whose next appearance might not come for centuries or longer.

When, Where and How to See Lemmon and SWAN Comets

Both comets are visible to skywatchers across the Northern Hemisphere.

Comet Lemmon (C/2025 A6), the brighter one, is best seen in the northwest sky about 90 minutes after sunset through October 21. It appears near the bright star Cor Caroli below the Big Dipper. It is bright enough to be seen with the naked eye from very dark locations about 90 minutes before sunrise in the northeast

Comet SWAN (C/2025 R2), slightly dimmer, glows low in the southwest near the Sagittarius constellation at the same time after sunset. It can be spotted by naked eyes if you are in a place with dark and clear sky; otherwise, use binoculars or small telescopes to help you see better. The optimal viewing window is about 30 minutes starting 90 minutes after sunset, during moonless skies coinciding with the peak of the Orionid meteor shower around October 20-21.

For the best viewing experience, head to locations far from urban light pollution with clear western and southwestern horizons. Popular stargazing apps like Sky Guide, Stellarium, and SkySafari provide real-time navigation to locate both comets in the sky by entering their names. Observers in dark-sky sites will have the clearest and most vivid views of these stunning celestial visitors.

PS. The image is for illustration purpose only​