New Comet C/2025 R2 (SWAN) Visible Without Telescope in October 2025
On October 20, Comet C/2025 R2 SWAN will make its closest approach to Earth – and the timing couldn’t be better! It’ll appear alongside bright Orionid meteors, near Comet Lemmon, and under a perfectly dark, moonless sky. Don’t miss this rare celestial spectacle! Track the comet’s path in real time with the free Sky Tonight app – just type its name in the app’s search bar. Keep reading to learn more about this spectacular visitor from the outer Solar System!
Contents
- Comet C/2025 R2 SWAN: General Info
- Comet C/2025 R2 SWAN Right Now
- Comet C/2025 R2 SWAN: Path in September-October 2025
- More About Comet C/2025 R2 SWAN
- New Comet C/2025 R2 SWAN: Conclusion
Comet C/2025 R2 SWAN: General Info
- Type: non-periodic comet
- Orbital period: 20,000+ years
- Perihelion: September 12, 2025
- Closest approach to Earth: October 20, 2025
- Maximum brightness: possibly up to mag 4
- Best visible from: Southern Hemisphere; Northern Hemisphere after the closest approach
Comet C/2025 R2 SWAN reached its perihelion on September 12, passing about 0.5 AU from the Sun, just outside Mercury’s aphelion. This comet belongs to the non-periodic type but is not a first-time visitor to the inner Solar System, which increases its chances of surviving the journey.
After perihelion, the comet’s brightness reached a magnitude of 7 to 6.5. It remains unclear whether this was caused by a sudden outburst or a gradual increase in brightness. If the latter is true, the comet could continue to grow brighter as it approaches Earth, coming as close as 0.261 AU.
Comet C/2025 R2 SWAN Size: Is It Really 100 Times Bigger Than 3I/ATLAS?
The internet loves a good space drama – this time, it’s about Comet C/2025 R2 (SWAN) supposedly being 100 times larger than the interstellar visitor 3I/ATLAS. Some even claim that the two comets are alien spaceships headed for a space battle behind the Sun. Unfortunately for sci-fi fans, there’s no scientific evidence to support these claims. These ideas stem from conspiracy videos, not from astronomers.
For one, the two comets are completely unrelated. C/2025 R2 (SWAN) is a long-period comet from the Solar System’s Oort Cloud, while 3I/ATLAS is an interstellar object that entered from beyond our Solar System. Also, the comets’ paths don’t cross behind the Sun – C/2025 R2 has already reached perihelion on September 12, while 3I/ATLAS will only approach the Sun on October 29. So, even if they were alien spaceships, 3I/ATLAS simply arrived too late for the battle.
As for SWAN’s spectacular tail, which some use as “proof” of its massive size, it tells us nothing about the comet’s nucleus. A comet’s brightness and tail length depend on how much gas and dust it releases, not on how large the comet really is.
In fact, no definitive scientific source currently provides the exact size of Comet C/2025 R2 (SWAN). However, its current brightness and activity are known, which is much more important for observers. Read on to learn about the current observation conditions for Comet C/2025 R2.
Comet C/2025 R2 SWAN Right Now
Right now, Comet C/2025 R2 SWAN is passing through the constellation Libra. At a magnitude of around 6, it can be observed with binoculars or captured with a camera equipped with a 200 mm lens. Currently best viewed from the Southern Hemisphere, the comet will become easier to spot from northern latitudes by late October. Look for the comet right after sunset on the west-southwestern horizon. Make sure you have an unobstructed view of the horizon.
To locate the comet more easily, use the free Sky Tonight app. Type “C/2025 R2 SWAN” in the search bar, tap the blue target button, point your device to the sky, and follow the arrow.
Comet C/2025 R2 SWAN: Path in September-October 2025
Here’s the path Comet SWAN will take over the next two months. Keep in mind that its exact orbit is still being refined, so there may be slight changes. We will keep this article updated.
Comet SWAN R2 September Visibility – First Appearance
Comet SWAN became visible with binoculars from the Southern Hemisphere, shining at around magnitude 7.
Key dates:
- September 12: reached perihelion (mag 7.2, 0.504 AU);
- September 15: passed at a distance of 20’ from Spica (mag 1);
- September 20: passed just over 1° from Mars (mag 1.6);
- September 28: entered the constellation Libra, moving northward across the ecliptic plane.
Comet SWAN R2 October Visibility – Best Seen in the Northern Hemisphere
Comet C/2025 R2 SWAN is expected to be visible in mid-October from the Northern Hemisphere. It will glow low above the southwestern horizon at dusk.
Between October 18 and 21, the comet will pass just 0.26 AU from Earth. If it stays intact, it could become a spectacular target for skywatchers and astrophotographers. Some optimistic predictions suggest that it could brighten to magnitude 4, which would make it visible to the naked eye under dark skies. However, comets are notoriously unpredictable, so consider this an exciting possibility rather than a guarantee.
Yet another bonus: On the evening of October 20, skywatchers get a triple treat. Look southwest to spot Comet C/2025 R2 (SWAN) glowing in Sagittarius, and northwest for Comet C/2025 A6 (Lemmon) in Boötes. Overhead, the Orionids will light up the sky with up to 20 bright, fast meteors per hour, streaking from Orion. And the best part? All of this happens under the New Moon, so the sky will be perfectly dark for viewing. If Monday stargazing isn’t your thing, you can start a night earlier on October 20 – though the meteor activity will be a bit lower. Truly, it’s a stargazer’s dream!
Key dates:
- October 2: passed near Zubenelgenubi (mag 2.8);
- October 9: passes near Theta Librae (mag 4.1);
- October 10: enters the constellation Scorpius;
- October 12: enters the constellation Ophiuchus;
- October 14: passes near Sabik (mag 2.5);
- October 15: enters the constellation Serpens Cauda;
- October 18: passes between M16 and M17 and crosses the galactic plane;
- October 20: reaches the closest approach to Earth (mag 7.3, 0.261 AU); enters the constellation Sagittarius;
- October 21: enters the constellation Aquila;
- October 24: borders the constellation Capricornus;
- October 26: enters the constellation Aquarius.
Comet SWAN R2 November Visibility – Farewell
On November 3, the comet crosses the celestial equator northward and begins its long journey back to the outer Solar System. It will gradually fade from view, disappearing from our skies until its next return – more than 20,000 years from now.
More About Comet C/2025 R2 SWAN
Comet C/2025 R2 SWAN Discovery
Comet C/2025 R2 SWAN was discovered on September 11, using images from the Solar Wind Anisotropies (SWAN) instrument aboard the SOHO spacecraft. The discovery was made by Ukrainian amateur astronomer Vladimir Bezugly, who noticed the comet moving across the SWAN field of view.
While SWAN images are great for discovering comets, ground-based confirmations are still often needed. To do this, Vladimir contacted Martin Mašek of the Institute of Physics of the Czech Academy of Sciences. On September 12, Martin used the FRAM telescope in Chile to check the discovery. He said: “I was very pleasantly surprised by such a bright comet with a long tail – I originally expected to be searching for a small, faint patch.” Vladimir agreed, noting that, “from my memory, this comet is one of the brightest among all comets we’ve ever discovered in SWAN images.”
Why wasn’t this bright comet detected earlier? Most likely, it was hidden behind or too close to the Sun, and may have only become visible after passing perihelion. Astronomers are now carefully comparing new observations to refine its trajectory and learn more about this cosmic visitor.
The comet was temporarily designated SWAN25B until it was given an official name by the International Astronomical Union – Comet C/2025 R2 SWAN.
What Does C/2025 R2 SWAN Mean?
The name of the comet contains data about its type, date of discovery, and discoverer:
- The letter “C” denotes a non-periodic comet. Such comets either pass through the Solar System only once or take more than 200 years to complete an orbit around the Sun.
- The designation “2025 R2” indicates that the comet was discovered in the first half of September 2025 and was the second comet discovered during that period.
- “SWAN” signifies that the discovery was made by the astronomical instrument called Solar Wind Anisotropies (SWAN).
Comet C/2025 R2 (SWAN) Origin: Is It an Interstellar Object?
Comet C/2025 R2 (SWAN) originates from the Oort Cloud, a vast reservoir of icy bodies at the outer edges of the Solar System. The Oort Cloud is home to the long-period comets. It’s big and vast, located between 2,000 and 200,000 AU from the Sun. Still, the Oort Cloud is part of the Solar System, which means that C/2025 R2 (SWAN) is not an interstellar object unlike the other comet that is about to appear in our skies – 3I/ATLAS.
Since both comets are arriving around the same time, some scientists – including Avi Loeb, the Harvard astronomer known for bold ideas about interstellar objects and alien technology – speculated they might share a common origin. Comet SWAN is even imagined as a separated module of an “alien ship.” But orbital calculations quickly ruled this out: Comet SWAN is approaching from Aquarius, while Comet ATLAS is coming from Sagittarius, separated by tens of degrees in the sky.
What makes Comet SWAN R2 unusual is its orbit, tilted only 4.5° relative to the ecliptic plane. This is quite low for a long-period comet from the distant Oort Cloud, which typically approaches from steep angles and random directions. SWAN R2's shallow orbit suggests that its trajectory may have been altered in the past, perhaps by a close gravitational encounter with a planet that altered its path.
Not the Only Comet in October
Comet C/2025 R2 (SWAN) isn’t the only visitor gracing our skies in October 2025. Early in the month, Comet C/2025 K1 (ATLAS) might become visible through binoculars, while C/2025 A6 (Lemmon) could brighten later on. With three bright comets to track, October promises to be an exciting month for skywatchers. Check our regularly updated article on the best upcoming comets, so that you never miss one!
New Comet C/2025 R2 SWAN: Conclusion
The newly discovered Comet C/2025 R2 SWAN is shaping up to be a spectacular sight in the coming weeks. Currently, it shines at magnitude 6 in the west-southwestern evening sky. It’s best seen from the Southern Hemisphere, but those in the Northern Hemisphere can also begin looking for the comet low on the horizon — it will become easier to see by late October.
Don't miss this opportunity! Track Comet SWAN easily with the free Sky Tonight app and be ready when it rises in your sky.
Wishing you clear skies and successful comet-hunting!
