A sharp but very welcome cold snap last week meant that many UK observers enjoyed their first views of Comet C/2022 E3 ZTF - which has become known as the 'green comet' - and were able to see with their own eyes the comet that observers in other parts of the world have been enjoying.

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And it was definitely worth the wait.

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Chart showing the location of Comet C/2022 E3 ZTF between 28 January and 4 February 2023. Credit: Pete Lawrence
Chart showing the location of Comet C/2022 E3 ZTF between 28 January and 4 February 2023. Credit: Pete Lawrence

Now that the comet has finally broken out of the constellation of Corona Borealis, where it has been for a long time, and is visible in both the morning and evening sky for observers at mid-northern latitudes, it is heading north, gaining speed as it pushes up past the handle of the Big Dipper en-route to its month’s end fly-by of Polaris, the Pole Star.

It is also increasing in brightness.

Stuart Atkinson captured this image of Comet C/2033 E3 (ZTF) on 21 January 2023 from Kendal, UK. Equipment: Canon EOS 700D DSLR camera, tracking mount.
Stuart Atkinson captured this image of Comet C/2033 E3 (ZTF) on 21 January 2023 from Kendal, UK. Equipment: Canon EOS 700D DSLR camera, tracking mount.

In fact, the comet is now regularly being reported to be brighter than mag. +6, technically making it a naked eye object, and some observers have reported seeing it without binoculars or telescopes from locations with very dark skies.

The comet has been observed and photographed by many people around the world, posting their images and observations online

Despite this, many UK observers hadn’t seen it with their own eyes since the start of the year, and some hadn’t seen it at all yet.

There was a lot of excitement about what the comet would look like.

How much brighter would it be? How long would the gas tail be? How much more obvious would the dust tail be?

Stuart Atkinson captured this image of Comet C/2033 E3 (ZTF) on the morning of 17 January 2023 from Kendal, UK. Equipment: Canon EOS 700D DSLR camera, tracking mount.
Stuart Atkinson captured this image of Comet C/2033 E3 (ZTF) on the morning of 17 January 2023 from Kendal, UK. Equipment: Canon EOS 700D DSLR camera, tracking mount.

As far as its brightness is concerned, Comet E3 is continuing to follow quite faithfully the early predictions of its brightness, based on its orbit and size.

It is around magnitude +6.5 now, and still on track for becoming a naked eye comet at the end of the month as it heads towards and then past Polaris, the Pole Star.

It won’t be obvious to the naked eye, like Comet NEOWISE was a couple of years ago, with its long curved tail and bright head, but it should be visible to the naked eye as a small smudge from a dark sky site on nights when there is no Moon in the sky.

Most people will still need binoculars or a telescope to see it.

Let's remind ourselves all about this wonderful comment, what it's been doing so far, and then take a look at what we can expect. Read on...

John Chumack captured this image of the comet shining at about mag. +8.2 magnitude in the constellation Corona Borealis on 29 December 2022 from Yellow Springs, Ohio, USA/
John Chumack captured this image of Comet C/2022 E3 (ZTF) shining at about mag. +8.2 magnitude in the constellation Corona Borealis on 29 December 2022 from Yellow Springs, Ohio, USA.

C/2022 E3 (ZTF) is a long period comet that was discovered by the Zwicky Transient Facility (hence the catchy name 'ZTF') on 2 March 2022, using the 1.2-m, f/2.4 Schmidt telescope at Mount Palomar.When it was discovered it was just a tiny, 17th magnitude smudge in Aquila, five times further from the Sun than Earth.

When astronomers crunched the numbers they found comet C/2022 E3 (ZTF) would reach perihelion – its closest point to the Sun - on 12 January 2023 and would then make a close approach to the Earth in early February 2023, when it might reach 6th magnitude.

Find out more about observing C/2022 E3 (ZTF) in our video guide to stargazing in January 2023 below:

Will C/2022 E3 (ZTF) be as bright as NEOWISE?

Steve Lewis managed to spot Comet NEOWISE over Stonehenge in the early hours of 22 July and photographed it using a Nikon D810 DSLR and Nikon 24-70 2.8 lens @ f2.8. Credit: Steve Lewis
Steve Lewis managed to spot Comet NEOWISE over Stonehenge in the early hours of 22 July 2020 and photographed it using a Nikon D810 DSLR and Nikon 24-70 2.8 lens @ f2.8. Credit: Steve Lewis

It’s important to say straight from the start that C/2022 E3 (ZTF) will not repeat the memorable show NEOWISE gave us.

If it does reach a magnitude between +5 and +6 as comet observers are hoping - and that’s by no means guaranteed - it will probably only be visible without help from binoculars or a telescope from a dark-sky site, away from light pollution.

A long misty NEOWISE-like tail is unlikely too.

Instead C/2022 E3 (ZTF) will more likely look like a smudge in the sky, like someone has dipped their finger in chalk dust and dabbed it on a blackboard.

Having said that, E3 will be high in the northern sky when it’s at its best, and will be moving quickly too as it drifts past Polaris, the North Star.

So even if it doesn’t dazzle us with a banner-like tail, Comet C/2022 E3 (ZTF) will still be well worth looking for.

And who knows, it might have a surprise or two in store for us.

Where is C/2022 E3 (ZTF) at the moment?

Chart showing the location of Comet C/2022 E3 ZTF in January 2023. Credit: Pete Lawrence
Chart showing the location of Comet C/2022 E3 ZTF in January 2023. Credit: Pete Lawrence

Comet C/2022 E3 ZTF reached perihelion on 12 January, its closest point to the Sun.

And that’s when things have begun to get interesting for comet observers here on Earth, because the comet passes by our world as it heads away from the Sun, and we will get our best views of it.

Chart showing how to find comet e3 ztf in the night sky
Chart showing how to find Comet E3 ZTF in the night sky

Comet C/2022 E3 ZTF: the story so far

Since early December 2022 Comet E3 has been moving with all the speed of a line for a post office counter at Christmas.

The weather over many parts of the UK over the festive period was pretty atrocious.

Christmas was wet and the New Year brought strong winds and lashing rain, so many amateur astronomers are yet to have their first views of Comet C/2022 E3 ZTF.

Firmly embedded within the constellation of Corona Borealis, the Northern Crown, it was just a tiny smudge at first, little more than an out of focus star, but as December passed it grew brighter and developed an ion tail too.

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But it only moved a small amount from morning to morning, crawling towards and then through the curve of the crown at a snail’s pace. That is about to change.

Stuart Atkinson braved the cold at 05:45 UTC on 7 December 2022 to capture this (cropped) image of Comet C/2022 E3 ZTF. Equipment: Canon EOS 700D DSLR camera, iOptron sky tracker, 80-300mm lens at 300.
Stuart Atkinson braved the cold at 05:45 UTC on 7 December 2022 to capture this (cropped) image of Comet C/2022 E3 ZTF. Equipment: Canon EOS 700D DSLR camera, iOptron sky tracker, 80-300mm lens at 300.

Having been visible in the evening sky through late summer and autumn, E3 was, as of early December, a morning object for northern observers, visible in the hours before dawn as a tiny 9th magnitude smudge through telescopes, close to the border between Serpens and Corona Borealis.

It was reserved for telescope owners, and even then looked like little more than a small, faint smudge, like a distant galaxy or nebula that had appeared out of nowhere to sit inside Corona Borealis.

As December progressed the comet began to develop and grow more interesting. Long exposure photos showed a short but obvious ion tail, looking like a faint grey-blue scratch behind its head, which itself had taken on a distinctly fan shaped appearance.

All this was in line with predictions, which was reassuring: if E3 had not started to develop like this it might have meant it was not going to become a naked eye object.

José J. Chambó captured this image of Comet C/2022 E3 (ZTF) on 24 December 2022 from Mayhill, New Mexico, USA.
José J. Chambó captured this image of Comet C/2022 E3 (ZTF) on 24 December 2022 from Mayhill, New Mexico, USA. Credit: José J. Chambó (www.cometografia.es)

By Christmas, long exposure photos taken through telescopes and processed to bring out details showed the comet’s ion tail starting to lengthen, brighten and split into at least two strands.

Its fan-shaped head was growing larger too, and the comet’s brightness was increasing in line with predictions, to the point where observers under very dark skies were reporting seeing it through binoculars.

As New Year approached the comet was being captured by astrophotographers with DSLRs and long lenses, tracking the sky on motorised mounts.

Some observers were reporting its brightness had increased to brighter than magnitude 9: another encouraging sign.

Later in December, C/2022 E3 (ZTF) drifted up into Corona and then worked its way slowly through the Northern Crown through Christmas and into the New Year.

Chart showing the location of Comet C/2022 E3 ZTF in Ursa Minor in late January 2023
Chart showing the location of Comet C/2022 E3 ZTF in Ursa Minor in late January 2023. Credit: Pete Lawrence

Comet E3 is really starting to develop nicely now, as of early January 2023, showing a long ion tail and bright, broad dust tail.

Long exposure photos are showing a lot of detail in its ion tail, including delicate puffs and tendrils of smoky blue-grey making their way down it.

And by now it is bright enough – perhaps magnitude 7 some think – that even single, untracked exposures taken using DSLRs, long lenses and high ISOs are recording the comet.

Not to tempt fate, but it’s looking promising for the future, and those predictions of E3 reaching naked eye brightness at the end of January and early February aren’t looking too outrageous.

Now it should begin to pick up speed, and brighten, and by mid-January 2023 C/2022 E3 (ZTF) will have crossed into northern Bootes, en-route to its 'fly-by' of Polaris in Ursa Minor at the end of January.

Then is should be visible in the northern sky all night and probably moving fast enough for its motion to be seen through binoculars.

However, it is still relatively tiny in the sky, and not yet quite naked-eye bright.

Comet C/2022 E3 ZTF observing notes

I enjoyed wonderful views of E3 early on the morning of 2 January.

Going out at just after 4am I set up my camera and tracker and pointed them towards the comet, and spent the next two hours taking lots of photos.

The comet was bright enough to be recorded as a tiny smudge on single, untracked short exposures of several seconds through my 135mm lens, and much more obvious when the exposure time was increased to 30s or longer and I swapped my 135mm lens for a 300mm lens, tracking the stars.

When I got home and stacked a lot of my images together the comet looked very pretty, with a short but broad fan-shaped dust tail.

Its much fainter ion tail was only just there on my images, but as I was taking them from the middle of light-polluted Kendal, UK, that wasn’t a huge shock.

Andy Smith captured this image of Comet C/2022 E3 (ZTF) from Oxfordshire, UK on 8 January 2023. Equipment: Modified Canon 90D DSLR camera, Explore Scientific CF127, iOptron CEM 70, LPro Max filter. Lights: 18 x 40s @ ISO 3200, Processing: APP Photoshop Lightroom
Andy Smith captured this image of Comet C/2022 E3 (ZTF) from Oxfordshire, UK on 8 January 2023. Equipment: Modified Canon 90D DSLR camera, Explore Scientific CF127, iOptron CEM 70, LPro Max filter. Lights: 18 x 40s @ ISO 3200, Processing: APP Photoshop Lightroom

It was a while before I managed to get another good view of Comet E3.

Since Christmas, my part of the world has been battered relentlessly by weather front after weather front, bands of wind and rain sweeping over us one after another, so I haven’t caught even a glimpse of the comet.

I had a near miss on the morning of 11 January when I was lured out of bed by the light of the Moon shining through my window at 4am.

But by the time I had reached my observing site the sky had clouded over and rain resumed, forcing me to throw a carrier bag over my camera and seek shelter.

Observers and photographers elsewhere, with better weather and clearer skies, are reporting that Comet C/2022 E3 ZTF is still small but developing nicely and remains on track to be visible to the naked eye from dark sky locations at the beginning of February, when it's at its closest to us.

Although a bright Moon has affected photography, images taken through telescopes tracking on the comet are showing its thin ion tail is lengthening and its broader dust tail is still visible too.

Neil Wilson captured this image of Comet C/2022 E3 ZTF) from Terrington, St. Clement, UK on 9 January 2023. Equipment: Altair 26C Protec camera, Celestron 9.25” EdgeHD + Hyperstar V4, Sky-Watcher AZ EQ6 mount. 60x10" light frames, gain 100, -10C; 20xdark frames. Capture: N.I.N.A., PHD2. Processing: Deep Sky Stacker, Starnet++, Photoshop.
Neil Wilson captured this image of Comet C/2022 E3 ZTF) from Terrington, St. Clement, UK on 9 January 2023. Equipment: Altair 26C Protec camera, Celestron 9.25” EdgeHD + Hyperstar V4, Sky-Watcher AZ EQ6 mount. 60x10" light frames, gain 100, -10C; 20xdark frames. Capture: N.I.N.A., PHD2. Processing: Deep Sky Stacker, Starnet++, Photoshop.

The good news right now is that Comet E3 is no longer exclusively a morning object - it is now visible in the evenings too, low in the north west as the sky darkens, down to the lower left of the end of the Plough's curved handle.

In fact, the comet is now circumpolar from the UK, meaning it never sets below the horizon.

Having been a morning object for a long time, E3 is now visible all through the night, at least from mid-northern latitudes.

After sunset it is very low in the north-west, and then swings down towards the northern horizon during the evening before swinging back up away from it again after midnight.

By the early hours of the morning E3 is high in the north east, well clear of all the trees and chimneys, and that’s when most people are observing and photographing it at the moment, but it won’t be too long until it is higher in the evening sky too.

Comet C/2022 E3 ZTF photographed by Stuart Atkinson from Kendall, Cumbria, UK on 2 January 2023 using a Canon EOS 700D DSLR camera on an iOptron Sky Tracker.
Comet C/2022 E3 ZTF photographed by Stuart Atkinson from Kendal, Cumbria, UK on 2 January 2023 using a Canon EOS 700D DSLR camera on an iOptron Sky Tracker.

The comet’s head is still showing a beautiful green hue on images, and some observers have reported seeing a subtle green tinge to the comet when looking at it through telescopes.

The comet’s gas or ion tail – the straight one that is pushed behind it by the gusts of the solar wind – continues to lengthen nicely.

Stacked, long exposure images taken through telescopes are now showing a lot of detail in this tail, twisted into knots here and there, and some have shown the tail split into two or more fine strands.

The comet’s dust tail, made of particles of dust that have drifted away from the comet, is now broadening into a fan and also getting brighter, and this is giving the comet an elongated appearance through binoculars and telescopes.

I managed to see and image the comet last week myself, in both the evening and the morning sky.

It had definitely grown brighter since the last time I saw it, back at the start of January, and my camera and tracker recorded both its tails much more easily this time, using 135mm and 300mm lenses.

Stuart Atkinson captured this image of Comet C/2033 E3 (ZTF) on the morning of 17 January 2023 from Kendal, UK. Equipment: Canon EOS 700D DSLR camera, tracking mount.
Stuart Atkinson captured this image of Comet C/2033 E3 (ZTF) on the morning of 17 January 2023 from Kendal, UK. Equipment: Canon EOS 700D DSLR camera, tracking mount.

Amazingly, after catching only fleeting glimpses of it for so long, I managed to see the comet from Kendal, Cumbria for three days in a row last week, in both the morning and evening sky, and even my images – taken with very basic equipment and processed using free software – show Comet E3’s tails and bright head very clearly.

During the past week the photographic appearance of the comet has changed quite dramatically too.

Long exposure images taken with telescopes and cameras tracking the comet as it moves across the sky have shown its ion tail flapping and swaying in the solar wind, like the tail of a kite, and there has been at least one 'disconnection event' where the ion tail effectively snapped off then grew back again.

The comet’s dust tail has grown in size and brightness too, and over the weekend it took on the appearance of a broad fan as the angle of our line of sight to the comet changed.

Many Images taken on Sunday 22 January showed the comet is now sporting an 'anti-tail': a spike of light on the opposite side of its head.

As impressive as these photos are, visually the comet is still a small object in the sky, and little more than a small elongated smudge in binoculars. Telescopes show its twin tails and bright head much more clearly.

The coming week will be a very important time for the comet, as it moves past the Big Dipper’s curved handle on its way towards Polaris.

It should brighten more, becoming more obvious in binoculars and telescopes, and we should see further development and growth of its tails.

If it brightens considerably it might even become visible to the naked eye for more people, but that’s not guaranteed.

All we can do is cross our fingers and wait. With great timing the Moon will be returning to the sky soon, which will affect the comet’s brightness, but it won’t drown it out altogether.

The Sky at Night presenter Pete Lawrence sent us this pic of Comet C/2022 E3, captured on the morning of 19 January.

The Sky at Night presenter Pete Lawrence sent us this pic of Comet C/2022 E3, captured on the morning of 19 January. Pete says: "This was an experimental image using a planetary camera (Player One Uranus-C) to take 30s shots over a 25 minute period centred on 02:10 UT. "The comet was just climbing over my roof top when I started this sequence and the skies were a bit hazy, eventually clouding over completely. Telescope used was a Takahashi E-130 Astrograph at f/3.3. "I've created a negative mono image version (right) to emphasise the ion tail. This was just starting to record on each 30s frame but is shown nicely here after registering and stacking on the comet."
Credit: Pete Lawrence

Pete says: "This was an experimental image using a planetary camera (Player One Uranus-C) to take 30s shots over a 25 minute period centred on 02:10 UT.

"The comet was just climbing over my roof top when I started this sequence and the skies were a bit hazy, eventually clouding over completely. Telescope used was a Takahashi E-130 Astrograph at f/3.3.

"I've created a negative mono image version (right) to emphasise the ion tail. This was just starting to record on each 30s frame but is shown nicely here after registering and stacking on the comet."

Unlike many that came before it, Comet E3 isn’t letting us down! It isn’t a Great Comet by any means, nowhere near as bright as comets like NEOWISE or Hale-Bopp, but it is definitely a great comet to photograph, beautiful and fascinating in its own right, definitely the most photogenic comet since NEOWISE, and is worth making the effort to go out and look for, especially if you can get to somewhere dark with as little light pollution as possible.

Inevitably the hype around this comet is growing – it’s just the way of things now.

Social media platforms are full of posts telling their readers how this "beautiful green comet" – not seen since cave men looked up at the night sky – is now visible, and will "zoom across the sky" at the end of the month.

In reality, Comet E3 is a very small and very faint object in the evening and morning sky.

Lots of non-astronomers are getting very excited when they read on Twitter and Facebook that it is "visible in binoculars" and it definitely is, if you know what you’re looking for.

But it is so small and so faint, really little more than an out of focus star still, that most people will go right past it as they sweep the stars with their binoculars.

It will hopefully become easier to spot as we get to the end of the month, when it is up near the Pole Star.

So, E3 is behaving itself – so far. Hopefully in the days and weeks ahead it will become a very nice binocular object, and visible to the naked eye under very dark skies. We’ll let you know…

What does Comet E3 ZTF really look like?

Comet C/2022 E3 ZTF photographed by Stuart Atkinson from Kendall, Cumbria, UK on 2 January 2023 using a Canon EOS 700D DSLR camera on an iOptron Sky Tracker.
Comet C/2022 E3 ZTF photographed by Stuart Atkinson from Kendal, Cumbria, UK on 2 January 2023 using a Canon EOS 700D DSLR camera on an iOptron Sky Tracker.

As I've already said above, I do feel a reality check is needed. Inevitably, the hype around this comet is starting to build and there is a lot of exaggerated reporting appearing on social media.

Not only are predictions being made about how E3 will "blaze in the sky" or "light up the sky", but some reports are claiming it is "spectacular!" now, based on its appearance in long exposure photos taken using sophisticated equipment and processed using specialised software.

It isn’t "spectacular", and even if it performs at its best it won’t be "spectacular". No-one should be predicting that, and we won’t be predicting that here at BBC Sky at Night Magazine!

But I think we can be hopeful that Comet E3 will in a few weeks’ time become bright enough to see with the naked eye from a dark sky site, which is in itself certainly something to look forward to.

Comet C/2022 E3 ZTF photographed by Stuart Atkinson from Kendall, Cumbria, UK on 2 January 2023 using a Canon EOS 700D DSLR camera on an iOptron Sky Tracker.
Comet C/2022 E3 ZTF photographed by Stuart Atkinson from Kendal, Cumbria, UK on 2 January 2023 using a Canon EOS 700D DSLR camera on an iOptron Sky Tracker.

It's true that Comet C/2022 E3 ZTF will be smaller and less obvious in the sky than Comet NEOWISE was a couple of years ago, and will look nothing like Comet Hale-Bopp, the 1996 comet so many people remember so fondly.

At its closest to Earth, E3 will be moving rapidly across the sky, enough that it will trail on long exposure photos, so taking lots of short exposure photos using a DSLR on a tripod and stacking them will give good results.

And who knows, if it undergoes an outburst as it passes us, we could yet be in for a treat!

So far E3 has been like one of those Olympic cyclists, going slowly round and around the track, waiting for the starting gun to fire.

Passing perihelion is that gun going off, and now the comet will pick up speed and really dig in as it pushes up into and through Bootes, through Hydra and then towards and past Polaris.

Now that E3 is heading away from the Sun and towards us, its motion across the sky will grow faster and its position in the sky will change more noticeably from night to night, or morning to morning, depending on when you are looking.

Indeed, from now on the comet’s position will change from hour to hour – not by a huge amount, we still won’t see it “streak across the sky” despite what some reporters are claiming, but enough that you’ll notice it if you’re photographing it or observing it through binoculars or a telescope.

How bright will C/2022 E3 (ZTF) get?

COMET C/2022 E3 ZTF
Comet chaser José J. Chambó captured this image of Comet C/2022 E3 (ZTF) on 2 September 2022 from Valles, Valencia, Spain. The comet can be seen in conjunction with blue star 23 Herculis (mag. +6.4). Equipment: Atik 383L+ camera, TS-Photon 8" N f/3.6

“How bright will Comet C/2022 E3 (ZTF) be?!” is the obvious question. The answer is – we don’t know.

Predicting the brightness of comets is never a good idea. Like newspaper horoscopes the predictions very rarely come true.

And it has been said famously that comets are like cats – they have tails and do exactly what they want.

But, if C/2022 E3 (ZTF) doesn’t 'do an ISON' and sputter out like a damp firework, it could be visible to the naked eye from a dark sky site in the early part of 2023, and binoculars should show it well.

We’ll just have to wait and see!

We'll keep you updated regularly on the comet’s progress and make sure you know when and where to look for it.

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Have you managed to observe or photograph Comet E3? Let us know by contacting us via contactus@skyatnightmagazine.com.

Authors

Stuart atkinson astronomy writer
Stuart AtkinsonAstronomy writer

Stuart Atkinson is a lifelong amateur astronomer and an author of popular astronomy books.