Next Comet Visible From Earth: How to See Comet Lemmon in October-November 2025
Good news for astronomy enthusiasts! A comet that was first thought to be unremarkable is exceeding expectations and brightening day by day. In October–November 2025, Comet C/2025 A6 (Lemmon) may be visible in binoculars and, in the best case, to the unaided eye. Start tracking it tonight with the free Sky Tonight app, and use this guide to plan your observations of the next bright comet.
Contents
- What you need to know about C/2025 A6 (Lemmon)
- How and where to find C/2025 A6 (Lemmon) in the sky?
- Discovery of C/2025 A6 (Lemmon)
- Let’s sum it up: key points about C/2025 A6 (Lemmon)
What you need to know about C/2025 A6 (Lemmon)
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A surprise brightener. Discovered on January 3, 2025, Comet Lemmon first appeared extremely faint (mag 21) and looked more like an asteroid. According to the initial forecast, the comet's maximum brightness was not expected to exceed telescope visibility. However, when the comet reappeared after its conjunction with the Sun, the first observations in August showed signs of increased cometary activity, and then the comet brightened quickly within a month.
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Likely the best comet of fall 2025. If the trend continues, late October could bring a bright comet easily visible in binoculars and possibly even without optics under a dark sky! There are no other comets at that time reaching that brightness. Note: comets are unpredictable, so treat this as an estimate, not a promise.
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Favors the Northern Hemisphere. The comet’s orbit is tilted by 144°, so the comet moves retrograde — opposite the planets’ usual direction — and reaches perihelion north of the ecliptic, favoring northern observers. By October 10, it even becomes circumpolar (never setting) for latitudes 48° N or above . Besides, its best evening visibility for many locations arrives in late October–early November, aligning with the long, clear autumn nights in the Northern Hemisphere.
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An ancient traveler. Comet Lemmon has passed near the Sun before and had an orbital period of about 1,350 years — in other words, people last saw it more than a millennium ago. However, this passage through our Solar System altered Lemmon's orbital period (which isn’t a rare event for comets in general). On April 16, the comet passed within 348.5 million kilometers (216.6 million miles) of Jupiter. Jupiter's gravitational field sapped some of Lemmon's orbital energy, shortening its period by about 200 years, and now it’s approximately 1,154 years.
How bright will C/2025 A6 (Lemmon) get?
Let’s talk about numbers. In astronomy, magnitude values work as follows: the lower the number, the brighter the object.
Early forecasts suggested a relatively faint comet — around magnitude 9 at the peak near perihelion in early November. However, after the solar conjunction on July 2, 2025, observations in mid-August showed stronger cometary activity and a rapid increase in brightness from magnitude 16.5 to 9 in roughly a month. By September, C/2025 A6 (Lemmon) had already exceeded its expected peak brightness and keeps growing brighter.
The current optimistic view puts the peak brightness near magnitude 4 in late October, which would make it a naked-eye object from dark locations and an easy target in binoculars. Some models even hint at a magnitude of 2 (which is an unlikely scenario), while cautious estimates suggest a magnitude of 7–7.5, which is still suitable for small telescopes and binoculars but not visible to the naked eye.
Remember: comets don’t follow scripts, so get prepared for surprises. Follow us on social media, where we will provide the latest updates on C/2025 A6 (Lemmon).
Where is C/2025 A6 (Lemmon) visible?
C/2025 A6 (Lemmon) is now a morning object in the Northern Hemisphere but moves into the evening sky by mid-October. Higher northern latitudes are especially favored — by this time, the comet even becomes circumpolar for the latitudes above 48° N.
By late October to early November, it may reach magnitude 4, then fade quickly afterward. From the Northern Hemisphere, it becomes unobservable in late November.
In the Southern Hemisphere, C/2025 A6 (Lemmon) is not well placed now, but should appear in mid-November.
Path of C/2025 A6 (Lemmon) in 2025
The comet is currently located against the backdrop of the Lynx constellation in the morning sky. It then passes through northern constellations — Leo Minor, Ursa Major, Canes Venatici, Boötes — and moves on to Serpens, Hercules, Ophiuchus. Around November 20, it disappears into evening twilight.
How and where to find C/2025 A6 (Lemmon) in the sky?
Here is the detailed path of Comet Lemmon so you know where to look to find it. Prefer the easy route? Open the free Sky Tonight app, search C/2025 A6 (Lemmon), and follow the on-screen arrow to the comet in your sky.
Second half of September: Visible before sunrise above the northeastern horizon in the constellation Lynx, moving to Leo Minor and then to Ursa Major by the end of the month. Faint, but could be visible via small telescopes. Elongation¹ ~55°.
Early October: Best visible before dawn (around 2 a.m. local time), rising highest shortly before sunrise. Look northeast, east of the Big Dipper, near the Ursa Major border. Elongation ~58°.
Mid-October: Shifts into the evening sky for many locations (some will still see it in the morning and evening). In the evening, look above the northwest horizon (west of the Big Dipper). In the morning, look northwest, north of the Big Dipper. On October 16, passes less than 1° from Cor Caroli (mag 2.9). Elongation ~48°.
Late October: Best visible in the evening. It’s better to wait until the sky is fully dark (astronomical darkness). Look above the western horizon in Boötes. Arcturus sits roughly 10° (one fist at arm’s length) below the comet. Elongation ~39°.
End of October–beginning of November (peak brightness): Look after dusk above the western horizon in Ophiuchus. The nearest bright star is Unukalhai (mag 2.6), about 8° to the west. Elongation ~33°.
Mid-November: After the November 8 perihelion, the comet will fade rapidly. It becomes observable in the Southern Hemisphere in the evening, staying low in the west in Ophiuchus. Elongation ~24°.
¹Simply put, elongation is the angular distance separating a celestial object from the Sun. The bigger the number, the better an object is visible, since sunlight doesn’t interfere with observations.
Moon phases
The Moon is a powerful source of light that can interfere with observations of fainter objects. So, aim for moonless nights for observations.
- New Moon: October 21
- First Quarter Moon: October 29
- Full Moon: November 5 (luckily, the comet will be on the opposite side of the sky)
- Last Quarter: November 14
See the Moon phases calendar on our website for more details.
Discovery of C/2025 A6 (Lemmon)
The Mount Lemmon Survey first recorded the object on January 3, 2025, at magnitude 21.5 — it was so faint it was first thought to be an asteroid-like object. Later, precovery images from Pan-STARRS (taken on November 12, 2024) were identified. Follow-up observations revealed a condensed coma (≈2.2 arcsec) and a short tail (≈2 arcsec, noted on February 21, 2025), confirming its cometary nature. One and a half months after its discovery, the object was announced as C/2025 A6 (Lemmon). C/2025 A6 (Lemmon) is dynamically old, meaning it has passed near the Sun before.
Let’s sum it up: key points about C/2025 A6 (Lemmon)
- Type: dynamically old, long-period comet
- Orbital period: 1,350 years (inbound)/ 1,154 years (outbound)
- Perihelion: November 8, 2025, at 0.53 AU
- Closest to Earth: October 21, 2025, at 0.60 AU
- Forecasted peak brightness: mag 4 (easy in binoculars; possibly naked-eye under excellent conditions) around perihelion on November 8, 2025
- Best visibility: Northern Hemisphere, late October – early November
C/2025 A6 (Lemmon) is a great target for late October to early November 2025. If the brightening continues, it could reach approximately magnitude 4, making it easily visible in binoculars and possibly even visible to the naked eye. The Northern Hemisphere gets the best view first; from the Southern Hemisphere, Comet Lemmon will be visible in mid-November. For the live position of the comet in your sky, use the free Sky Tonight app.
