You may have heard news that there's a new comet visible in the morning sky.
It's called C/2025 F2 (SWAN) and can be found in the morning sky not far from the star Mirach, tracking eastwards through the edge of the constellation of Andromeda and making its way towards Triangulum.
Discovering C/2025 F2 (SWAN)
Comet C/2025 F2 (SWAN) had rather a complicated discovery story.
When Comet Hale-Bopp was discovered 30 years ago, most comets were found by amateur astronomers looking throughout telescopes, scanning the sky searching for them.
These days the vast majority of comets are found by arrays of robotic survey telescopes, such as PANSTARRS and ATLAS.
Comet F2 was found using a combination of the two.
Several comet observers poring over images taken by the SWAN (Solar Win Anisotropies) camera onboard NASA’s SOHO solar observatory independently spotted what they thought might be a comet moving through them.
Soon the comet had been seen, and word went around the comet-observing community that there was a new comet visible in the sky.
They gave it the informal name 'Comet SWAN F2' while they waited for it to be confirmed and named officially.
Now observers around the world are getting up before sunrise to swing their telescopes and cameras towards the comet, hoping to see and image this new celestial visitor.
In this blog we'll provide regular updates as to how you can see it for yourself.
Late April 2025
If you haven't seen Comet C/2025 F2 (SWAN) yet – and to be fair, not many people have, because it's faint and awkwardly placed – you should grab the next opportunity you get, because it might not be around much longer...
The comet is currently visible in the morning sky, as of late April 2025, for sleep-deprived northern hemisphere viewers.
You can find it not far from the star Mirach, slicing eastwards through the edge of the constellation of Andromeda en route towards Triangulum.
At the time of our first update in early April 2025, when it was still just within the Great Square of Pegasus, Comet C/2025 F2 (SWAN) was reported to be shining somewhere between magnitude +8 and +9, and had a whip-thin tail that could be traced to a length of around a degree or so on long exposure photographs.
At that time, comet observers were cautiously looking forward to it brightening and its tail increasing in length as it moved up into the evening sky, heading towards perihelion.
Their hope was that as it approached perihelion, amongst the stars of Taurus low in the evening sky after sunset the comet would brighten to 5th or even 4th magnitude, making it visible in binoculars and on camera, even though its low altitude in the twilight sky would make it very challenging.
However, the most recent observations are less than encouraging.
The comet hasn't brightened as expected, and some observers have even reported it has faded to almost 10th magnitude.
The comet's coma - its head - has also shrunk in size photographically and, according to some observers now appears elongated.
The tail has shrunk considerably, too.
What does all this mean? It might confirm the suspicions of comet observers who thought that Comet C/2025 F2 (SWAN) had an 'outburst' of activity earlier in the month, and has now simply settled down into its normal behaviour and is doing exactly what it should be doing.
Or it could mean that the comet has started to disintegrate. If that's the case the outlook isn't good: the comet might not last long enough to whip around the Sun.
While this might be disappointing, it’s just what comets do.
Predicting a comet’s future behaviour after it is discovered is always unwise, and as a cat owner myself I agree with the quote that says "Comets are like cats – they have tails and do precisely what they want".
But as we made clear in the first report (below), Comet C/2025 F2 (SWAN) was never going to be a bright, naked-eye comet anyway, and it certainly was never going to 'light up the sky'.
Even if the most optimistic predictions of its brightness had been correct it would still have been a very challenging sight at perihelion as it moved through Taurus, passing the Pleiades and Hyades cluster low in the twilight.
But don’t count Comet C/2025 F2 (SWAN) out just yet!
As one of the brightest comets in the sky right now it’s still definitely worth tracking down, if you don’t mind getting up early or staying up late.
And it’s always fascinating and rewarding to watch how comets like these develop and change as they approach and then round the Sun.
If you want to find it, you can use an astronomy or stargazing astronomy app to pin down its location in the sky, or select it from the solar system menu of your smart telescope.
Or just point your binoculars, telescope or camera at Mirach and look for the comet nearby.
Just don’t leave it too long…
Blog entry: Comet C/2025 F2 (SWAN) early April
The comet is currently very small – much smaller visually than the nearby globular cluster M15 - and essentially looks like an out-of-focus star through telescopes.
Long exposure photos taken through telescopes show it has a whip-thin tail, already at least a degree long, and also bring out the comet’s strong green colour.
Comet F2 will soon exit the Great Square of Pegasus, heading towards the adjoining Andromeda constellation.
It's going to brighten as it does, but will be fighting the brightening of the sky too, so it's going to be a challenge seeing it even with binoculars.
Cameras should still be able to pick it up, and it will be easy to find and image with smart telescopes like the SeeStar and Dwarf.
If you do want to see it through binoculars or a telescope, remember you're going to be observing in the area of the sky in which the Sun rises, and just before it rises.
This means caution must be taken, as if you catch a glimpse of the Sun through binoculars or a telescope, you could damage your eyesight.
What's in store for the comet
Comet C/2025 F2 (SWAN) is due to reach perihelion – its closest point to the Sun – on 1 May 2025.
By then it will be an evening object in the constellation Taurus, and is predicted to reach a maximum brightness of around +4.
That would make it a good naked-eye comet if it was high in a dark sky.
But it's not going to be high in a dark sky, at least not from the UK and mid-northern latitudes.
In May 2025, Comet C/2025 F2 (SWAN) will be low in the northwest twilight after sunset, close to the Pleiades star cluster, arcing past it on its way towards a passage through the neighbouring Hyades cluster.
Again, that proximity to the Sun means caution should be taken. Don't attempt to observe the comet until the Sun has set below the horizon.
So, unlike Comet Hale-Bopp which shone in our sky 30 years go, and unlike the bright comet C/2023 A3 – that was such a lovely sight in our sky in 2024 – this icy visitor will be very challenging to see, I think, hanging faint and low in a post-sunset sky.
But it'll still be worth a go: it always is. And who knows? If its tail grows longer that might help it shine through the twilight, but don’t count on it.
Southern hemisphere observers will enjoy better views than northern hemisphere observers. Again…
We'll continue to give updates about this new comet. In the meantime, if you want to find it, it's available on the major stargazing and planetarium apps.
If you photograph Comet C/2025 F2 (SWAN), we'd love to see your images! Send them to us by emailing contactus@skyatnightmagazine.com
