It’s not every night you get to see a comet streak across the sky — and this month, we’re lucky enough to have two. So grab a blanket, head outside after sunset, and get ready for a rare celestial treat.
Two comets, one sky
Events like this don’t happen often. But in October, stargazers across the Northern Hemisphere will have the chance to spot not one, but two glowing green comets lighting up the night sky. Both hail from the far edges of our solar system, and both are releasing gas that gives them their distinctive emerald tint.
Comet Lemmon: the classic beauty
After 3 days of coming up to this spot with a vision, the clouds finally cleared (well kind of). The clouds decided to drift under Comet C/2024 A6 Lemmon opposed to over it and gave me this incredible view last night. ☄️ pic.twitter.com/PsK2gRxNB6
— KRL (@KennethLerose) October 16, 2025
The first is Comet C/2025 A6 (Lemmon), discovered by the Mount Lemmon Survey in Arizona — hence its name.
I woke up early to capture Comet “C/2025 A6 (Lemmon)” before sunrise. But it’s starting to rise higher in the evening each day after sunset and will be much brighter near the end of the month. I used my Celestron RASA telescope, ZWO ASI533MC camera, and an Antlia L-Filter. pic.twitter.com/jzyoX0hR9m
— Chuck’s Astrophotography (@chucksastropho1) October 15, 2025
In recent weeks, observers have reported that it’s now just visible to the naked eye under perfectly dark skies, far from city lights.
#PPOD: Comet Meets Aurora 🌠
Comet C/2025 A6 (Lemmon) is brightening fast! Discovered in January by the Mount Lemmon Survey, it swings closest to Earth on October 21 and reaches perihelion on November 8—about 79 million kilometers from the Sun. Currently around magnitude 5.4,… pic.twitter.com/J64FpPH4M8
— The SETI Institute (@SETIInstitute) October 15, 2025
Right now, Lemmon is gliding through Ursa Major (the Big Dipper), positioned just below the handle around October 21, as it heads toward the constellation Boötes.
The tree is not in danger. That’s because the comet pictured just above it, Comet C/2025 A6 (Lemmon), is far in the distance, well away from the Earth. Comet Lemmon now continues to brighten as it arcs through the inner Solar System, even though it has passed its nearest to the… pic.twitter.com/buUIARTdAY
— Astronomy Picture of the Day (@apod) October 14, 2025
That date — October 21 — will also mark its closest approach to Earth, when it passes within 90 million kilometers (56 million miles). The timing couldn’t be better: a new moon means darker skies and ideal viewing conditions. With a smartphone and a steady tripod, you might even snap a respectable photo of it yourself.
Brilliant image of Comet C/2025 A6 Lemmon which is now a faint naked eye object. Credit Jason L Dain. pic.twitter.com/yBhz45FJ7J
— Con Stoitsis (@vivstoitsis) October 15, 2025
And that’s not all. The same night, the Orionid meteor shower will peak — an annual display created by debris from Halley’s Comet, the most famous comet of all.
Jumping Pound Alberta 20251015T0300-0430Z
1st image Comet C/2025 R2 SWAN
2nd image C/2025 A6 Lemmon
3/4th image the Aurora Borealis
Astrophotograhy nights don’t get much better that tonight, 2 comets and the aurora. I was taking down my set up when i noticed the low horizon… pic.twitter.com/Unvy9nXeOP
— Harlan Thomas (@theauroraguy) October 15, 2025
Comet Swan: the newcomer
A newly discovered comet is already visible with binoculars. The comet, C/2025 R2 (SWAN) and nicknamed SWAN25B, is brightening significantly as it emerges from the Sun’s direction and might soon become visible on your smartphone — if not your eyes. Although the brightnesses of… pic.twitter.com/olCjX0eiQI
— Astronomy Picture of the Day (@apod) September 17, 2025
Our second cosmic visitor, Comet C/2025 R2 (Swan), was first spotted just last month as it neared the Sun. It was detected by the Solar Wind Anisotropies (SWAN) instrument, which is how it got its name.
Comet C/2025 R2 (SWAN) pic.twitter.com/VHmDcbJUrU
— Space 8K (@uhd2020) September 18, 2025
Currently shining at about magnitude 6, it sits right at the limit of naked-eye visibility. Because a comet’s light is spread out rather than pinpointed like a star’s, it can be harder to spot — so a pair of binoculars will definitely help.
A new visitor from the outer Solar System, comet C/2025 R2 (SWAN) also known as SWAN25B was only discovered late last week, on September 11. That’s just a day before the comet reached perihelion, its closest approach to the Sun. First spotted by Vladimir Bezugly in images from… pic.twitter.com/yQN0k5Cvmh
— Astronomy Picture of the Day (@apod) September 20, 2025
Swan will make its closest approach to Earth slightly earlier than Lemmon — on October 20, passing just 39 million kilometers (24 million miles) away.
Another incredible image of Comet C/2025 R2 SWAN done by Gerald Rhemann and Michael Jäger last September 15th from Namibia…
Wow‼️ pic.twitter.com/EAb3BErEyy
— Xavi Bros (@Xavi_Bros) September 16, 2025
As it climbs higher in the night sky, it will move through the constellations Scutum (the Shield) and Aquila (the Eagle), making it easier to find in the southern sky.
Comet Observations from Caulfield this evening.
Comet C/2025 R2 Swan
Oct 15.38 UT, m1 5.7, DC 5/, Dia 10’.
20x80mm B
Close to star HD 157969 made estimates difficult.
Seestar images show how quicky the comet is moving pic.twitter.com/JxAi3Na5Y6
— Con Stoitsis (@vivstoitsis) October 15, 2025
So, set your alarm, dust off your binoculars, and head outside. Two comets in one week — plus a meteor shower — is an astronomical show you won’t want to miss. And who knows? Before long, the interstellar visitor 3I/Atlas might join the party too.
Nathalie Mayer
Journalist
Born in Lorraine on a freezing winter night, storytelling has always inspired me, first through my grandmother’s tales and later Stephen King’s imagination. A physicist turned science communicator, I’ve collaborated with institutions like CEA, Total, Engie, and Futura. Today, I focus on unraveling Earth’s complex environmental and energy challenges, blending science with storytelling to illuminate solutions.