Two Green Comets Tap the Night Sky: Lemmon and SWAN
As the sky darkens this week, two green comets are making their well-timed return to observers with binoculars. Comet Lemmon (C/2025 A6) and Comet SWAN (C/2025 R2) have shifted from morning-only sightings to more convenient evening viewing, offering a rare chance to watch two active comets at once while they brighten in the weeks surrounding the Orionid meteor shower. For skywatchers in mid-northern latitudes, Monday, Oct. 13, 2025, marks a prime opportunity to spot these icy wanderers low in the twilight.
What to Look For On Monday, Oct. 13, 2025
Both Lemmon and SWAN will be binocular-friendly and visible in opposite corners of the sky after sunset. Lemmon appears low in the northwest about 90 minutes after sunset, while SWAN glows in the southwest beneath the bright star Sabik, just above Antares in Scorpius. A waning gibbous moon rising late at night will not overshadow their glow, making this a good window for a quick, repeatable sighting session.
Best Times to See Lemmon
After sunset, locate Lemmon just below the curved handle of the Big Dipper. In New York City, with a sunset around 6:16 p.m. EDT, the ideal 30-minute viewing window is roughly 7:46–8:16 p.m. EDT. The comet will hover about 7 degrees above the northwest horizon at that time—roughly the width of four fingers held at arm’s length—and will descend as twilight deepens. Lemmon also reappears before dawn, in the northeast, to the right of the Big Dipper’s handle and roughly level with the star Alioth. From New York, expect a 5:35–6:05 a.m. EDT window, with Venus rising in the east, offering a second chance to catch this green visitor.
Best Times to See SWAN
Comet SWAN will glow bluish-green in binoculars low in the southwest after sunset, appearing just beneath Sabik in Ophiuchus and above Antares in Scorpius. In New York, SWAN should reach about 19 degrees altitude soon after 7:46 p.m. EDT, roughly the distance from your little finger to your forearm when held at arm’s length. It will gradually sink toward the horizon as twilight fades, but still offer a reliable binocular sighting as long as the Moon remains a minor presence in the sky.
Why This Week Matters for Viewers
The two comets peak around Oct. 20–21, coinciding with a new moon and the Orionid meteor shower. This combination could yield excellent dark-sky conditions and a memorable display, with the potential for bright comets and a crowded meteor shower contributing to a dramatic night sky. Even for casual stargazers, the chance to observe two green comets near familiar stars enhances the week’s skywatching excitement.
Practical Tips for Photographing The Comets
To capture these comets, you can use a smartphone in night or pro modes or a DSLR/mirrorless body on a tripod. Quick guidelines: start with ISO 800–1600, aperture f/2.8–f/4, and shutter speeds of 2–5 seconds for dusk shots. If you’re in light-polluted areas, raise ISO slightly and shorten exposures to keep stars sharp. First locate the comets with binoculars, then frame with a longer lens if you have one. Manual focus on a bright star using live view or infinity helps lock in the shot. Even if tails aren’t obvious to the naked eye, they often show up in images.
Stay Informed
Check daily comet tracker updates for finder charts and tips tailored to mid-northern latitudes, as conditions can shift with weather and moonlight. A steady routine of viewing windows will increase your chances of catching Lemmon and SWAN in the same season’s best light.
