Space

New comet C/2025 R2 (SWAN) is up after sunset

Posted by
Eddie Irizarry
and
October 22, 2025
Finder chart showing the path of Comet SWAN across the sky.
Look southward for Comet C/2025 R2 (SWAN) from about October 22, 2025, through early November. The comet is fainter than Comet Lemmon, but binoculars might pick it up. Image via Bob King, aka AstroBob.

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If you like Comet SWAN, you’ll love Comet Lemmon, which is forecast to become even brighter than SWAN! Read about Comet Lemmon here. And don’t forget about our interstellar comet, 3I/ATLAS. October 2025 is a great month for comets!

New comet soars into the sky

Comet C/2025 R2 (SWAN) – confirmed in September 2025 in images from the SOHO spacecraft’s SWAN camera – is still shining at about 6th magnitude. That’s just within the limit for visibility with the unaided eye. This comet is within reach of ordinary binoculars, especially under dark skies. Plus, you might also be able to pick up the comet in long-exposure photographs.

To see the comet, look southward when true darkness falls, say, about 90 minutes after sunset. This comet started out being visible mainly to observers in the Southern Hemisphere. It has now passed closest to Earth (around October 19). And it’s about as bright as we’re going to see it now, as it gradually moves away from the sun and Earth.

Bright green comet with a faint tail.
Comet SWAN on October 19, 2025 via Chris Schur in Arizona. Note that the comet’s tail is now fading from view. But it’s still very green! Thank you, Chris Schur! Visit Schur’s website portal.

More facts about the new comet

The Solar Wind Anisotropies (SWAN) instrument on the SOHO spacecraft confirmed this comet on September 12.

The International Astronomical Union gave the comet its official name: C/2025 R2 (SWAN). It was originally and temporarily designated SWAN25B.

When SWAN passed Spica

Gerald Rhemann of Austria took this photo of comet C/2025 R2 (SWAN) on September 15 when it was near the bright blue-white star Spica in the constellation Virgo the Maiden. Beautiful! Image via Gerald Rhemann. Used with permission.
Bright star at the top with a comet in the lower right.
Michael Matiazzo in Adelaide, South Australia, captured this image on September 14, 2025. It’s comet C/2025 R2 (SWAN), formerly known as comet SWAN25B. It shows an impressive, 2.5-degree-long tail, which translates to about 5 full-moon diameters long! The bright star in the upper left of the image is Spica.

More on the comet’s path

By tracking its path, NASA/JPL has been able to determine an orbit for comet C/2025 R2 (SWAN). It suggests this comet completes an orbit around the sun every 22,554 years!

This means that if you are able to see the new comet C/2025 R2 (SWAN) using binoculars or with a camera, this will be a once-in-a-lifetime sighting. If the comet survives this pass, it will return around the year 24,579.

Some images of the comet

Person with a headlamp looking at a sky filled with the Milky Way plus a green, fuzzy light.
View at EarthSky Community Photos. | Julie Machado in Auckland, New Zealand, captured Comet SWAN (the green light above the horizon) and the Milky Way on October 17, 2025. Julie wrote: “After weeks of cloudy nights, I was lucky to have one clear evening to capture the comet, while my partner climbed the dune summit. Though too faint to see with the unaided eye that night, its subtle green glow was captured here alongside the Milky Way and the soft hues of surrounding nebulae.” Thank you, Julie!
Top and bottom images in different light of a comet with a long tail.
View at EarthSky Community Photos. | Filipp Romanov from Russia, using a large remote telescope in Australia, captured this view of the new comet on September 13, 2025. Filipp wrote: “I confirmed the new bright comet SWAN25B remotely using iTelescope.net.” Thank you, Filipp!

Comet with a long tail on a starry background.
View larger. | Australian comet expert Michael Mattiazzo< captured this image of the new comet on September 12, 2025. Used with permission.[/caption] [caption id="attachment_521602" align="alignnone" width="800"]New comet SWAN25B: Black-and-white image of a comet with a long tail next to a false-color version. Comet SWAN R2 is already shining (relatively) brightly, though it’s close to the sun. Image via E. Guido/ M. Rocchetto/ J. Ferguson/ Spaceflux/ X. Used with permission.

Early observations of the new comet

Comet hunter Vladimir Bezugly detected the new comet in recent SWAN images. Meanwhile, comet astrophotographers are capturing nice images of the new celestial visitor. Comet expert Michael Mattiazzo said:

I was able to visually see it this morning (September 12) using 15 x 70 binoculars from Australia.

Martin Mašek of the Institute of Physics of the Czech Academy of Sciences, at the Cherenkov Telescope Array site near Cerro Paranal, also confirmed the new comet on the ICQ Comet Observations Facebook page. Mašek 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.

Sky photo with stars in black on white showing a small black object with a very long tail.
Martin Mašek of the Institute of Physics of the Czech Academy of Sciences at the Cherenkov Telescope Array in Chile captured this image of comet SWAN R2. Image via ICQ Comet Observations.
Starry sky with a comet near bottom and tail extending upward to left.
Comet expert Michael Mattiazzo reported Comet R2 SWAN at magnitude 5.9 and shared the image above. In fact, Mattiazzo captured the image without using a telescope. He used a 200mm lens. The photo shows a nice tail of comet R2 SWAN, and if you look carefully at top right, the faint object (small green dot) in the circle is the famous interstellar comet 3I/Atlas, which is not too far from the area in the sky where we currently see Comet R2. This might be one of just a few images in which the interstellar comet 3I/Atlas has been captured without a telescope!Used with permission.

So why haven’t we seen this bright comet before now? The new comet was apparently behind, or too close to the area where we see the sun, and perhaps has appeared just after its perihelion. However, scientists are still comparing observations of the comet to determine its exact trajectory.

Bottom line: As of October 22, new comet C/2025 R2 (SWAN) is still shining at 6th magnitude, meaning it’s within the limit for viewing with the unaided eye. But binoculars will show it better!

Posted 
October 22, 2025
 in 
Space

Eddie Irizarry

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About the Author:
Eddie Irizarry of the Sociedad de Astronomía del Caribe (Astronomical Society of the Caribbean) has been a NASA Solar System Ambassador since 2004. He loves public outreach and has published multiple astronomy articles for EarthSky, as well as for newspapers in Puerto Rico. He has also offered dozens of conferences related to asteroids and comets at the Arecibo Observatory. Asteroid 33012EddieIrizarry, a 7.8 km space rock, has been named in his honor.

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