Tail 10 Moons Long! New Comet C/2025 R2 SWAN in September 2025
A new cosmic visitor is here! Discovered on September 11, Comet C/2025 R2 SWAN is already showing off with a magnitude of 7–6.5 and a spectacular 5° tail. Currently, the best views are from the Southern Hemisphere, but observers in the Northern Hemisphere may also see it in October. You can track the comet’s path right now in your sky with the free Sky Tonight app – just search for the comet’s name in the app. Remember, though, C/2025 R2 SWAN is currently close to the Sun, so observe with caution. Read on to get to know C/2025 R2 SWAN!
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 19, 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.
Already, the comet has developed a striking corkscrew-shaped 5° ion tail – about the length of 10 Full Moons lined up in the sky! 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 and extend its tail even further as it approaches Earth, coming as close as 0.261 AU.
Comet C/2025 R2 SWAN Right Now
Right now, Comet C/2025 R2 SWAN is passing between Mars and Spica in the constellation Virgo. At a magnitude of around 7, it can be observed with binoculars or captured with a camera equipped with a 200 mm lens. Because it’s still close to the Sun, spotting it won't be easy, but observers in the Southern Hemisphere can already give it a try. Look for the comet right after sunset on the western horizon. Make sure you have a clear, 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. Tip: Mars and Spica can help confirm the comet’s position. You'll find C/2025 R2 SWAN just below Mars and above Spica.
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.
C/2025 R2 SWAN in September 2025 – First Appearance
Comet SWAN became visible with binoculars from the Southern Hemisphere, shining at around magnitude 7 with a long 5° tail.
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: passes just over 1° from Mars (mag 1.6);
- September 28: enters the constellation Libra, moving northward across the ecliptic plane.
C/2025 R2 SWAN in October 2025 – Best visibility in the Northern Hemisphere
In October, Comet C/2025 R2 SWAN may become visible 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.
Also, on October 4–6, the Earth may pass through the comet’s debris stream. If that happens, we could be treated to a brand-new meteor shower!
Key dates:
- October 2: passes 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 19: reaches the closest approach to Earth (mag 7.3, 0.261 AU);
- October 20: enters the constellation Sagittarius;
- October 21: enters the constellation Aquila;
- October 24: borders the constellation Capricornus;
- October 26: enters the constellation Aquarius.
C/2025 R2 SWAN in November 2025 – 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).
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 7 in the western evening sky of the Southern Hemisphere. Starting in early October, skywatchers in the Northern Hemisphere may also get the chance to see it.
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!
