Next Comet Visible From Earth: How to See Comet Lemmon in October-November 2025
Good news for astronomy enthusiasts! There is a comet that is brightening day by day and may become visible to the unaided eye. In October-November 2025, watch Comet C/2025 A6 (Lemmon) glowing in the sky — use the free Sky Tonight app to track it tonight. This guide will help you plan your observations and prepare for capturing 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?
- How to photograph Comet C/2025 A6 (Lemmon) (guide for beginners)
- 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)
- The best time to observe Comet Lemmon from the Northern Hemisphere is from October 12 to November 2. During this time, C/2025 A6 will be near Earth and will be visible to the naked eye under dark skies, away from city lights. The comet is expected to reach peak brightness around October 31 or November 1.
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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 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 probably 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 higher, though this area will gradually shrink and shift farther north. 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 forecast puts the peak brightness near magnitude 3.7 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 or brighter, while more cautious estimates suggest a magnitude of 4, which is still suitable for binoculars and may be faintly visible to the naked eye under perfect observing conditions.
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, the comet may reach magnitude 3-4, then fade quickly afterward. In late November, it sits very low in the bright evening twilight for most northern observers, making it practically unobservable.
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.
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.
How to photograph Comet C/2025 A6 (Lemmon) (guide for beginners)
The comet won’t stay long — but your photos will. Comet Lemmon offers a perfect chance to practice astrophotography — it’s expected to be the brightest comet of 2025, visible under dark skies with a long tail stretching several degrees across the sky, making it especially rewarding to photograph.
When photographing a comet, keep two things in mind:
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Comets move across the sky. Short exposures of a few dozen seconds won’t show much motion, but in longer sequences or stacked images, the comet’s core may slightly shift compared to the stars.
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Dark skies matter. Light pollution and moonlight reduce contrast. For best results, choose dark conditions. The free Sky Tonight app can help you locate the comet, check its altitude, and find the observing time when the sky is darkest.
Next, let’s explore how to capture the comet using different gear — from a smartphone on a tripod to a camera with a star tracker or even a telescope.
Photographing with a smartphone
Using just your phone, the comet will likely appear as a faint, fuzzy spot, and the tail may be barely visible — but it’s still worth a try! If you can’t see Comet Lemmon with the naked eye, a picture might reveal it. Just find the comet’s location in the sky with the free Sky Tonight app, take a picture with the right settings, and voilà! Here's how to capture it:
- Set your phone on a tripod or stable surface.
- Turn on Night mode or Astrophotography mode (available on some phones).
If your phone supports Pro/Advanced mode, adjust the settings manually. Here is a short settings guide:
- ISO (sensitivity): Use 1600–3200. Higher ISO settings make the image brighter but also add noise.
- Exposure (shutter speed): Set to 5-10 seconds. Longer exposures may blur stars and the comet.
- Aperture (f-number): Usually fixed on phones. A lower number (like f/1.8) lets in more light.
- Zoom: Stick to 1× or 2× for clarity. At 0.5× wide-angle, the comet looks too small. At 2×, it stands out more while still showing the surrounding sky. If your phone supports 3× or higher, try it for a closer view of the comet.
Photographing with a camera + tripod
This is the first step beyond smartphone photography. With this setup, you can capture either a wide-field shot of the comet in a landscape or a closer view showing the comet and its short tail.
- Lens: 14-35 mm for landscapes; 85-135 mm for closer comet shots.
- ISO: 1600-3200.
- Exposure: 10-20 seconds with a wide-angle; 5-10 seconds with a short telephoto to avoid star trailing.
- Aperture: As wide as possible (f/2-f/2.8).
- Focus: Set manually on a bright star near the comet.
Tip: The Sky Tonight app in AR mode can help you align the comet with a landmark, such as a tree, mountain, or building, for a striking composition.
Photographing with a camera + tripod + telephoto lens or telescope
This setup lets you zoom in for a larger image of the comet’s nucleus and part of its tail. Without tracking, however, you’ll be limited to short exposures.
- Focal length: 200-500 mm telephoto lens, or a small telescope (80-100 mm aperture).
- ISO: 1600-3200.
- Exposure: Very short, 1-5 seconds to avoid smearing.
- Aperture: Around f/4-f/5, typical for telescopes.
You’ll capture a sharp cometary core with a faint hint of the tail. To reveal more detail, take multiple short frames and stack them during processing.
Photographing with a camera + tripod + star tracker
A star tracker follows the sky’s motion, allowing longer exposures that reveal faint details in the comet’s tail.
- Lens: 50-200 mm.
- ISO: 800-1600.
- Exposure: 30-120 seconds, depending on focal length.
- Aperture: f/2-f/4.
- Technique: Create two stacks — one aligned with the stars and one with the comet. Combine them during processing to get both stars and the comet to look sharp in the picture.
Photographing with a camera + tripod + star tracker + telephoto lens or telescope
This setup provides the most detailed results, capturing fine tail structures and even subtle color variations (ion tail vs. dust tail).
- Focal length: 300-500 mm lens, or a small refractor telescope.
- ISO: 800-1600.
- Exposure: 20-60 seconds per frame.
- Aperture: f/4-f/5 (typical for telescopes).
- Stacking: Align frames on the comet to keep its nucleus looking crisp and clear.
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.
