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You have likely heard about the “green comet” that’s all over the news. It is known as Comet C/2022 E3 ZTF, and it is currently visible in the night sky.

This particular comet only comes around approximately every 50,000 years, so I set up my camera and telescope to photograph it while it is still here. 

In this post, I will explain my approach and provide some photography tips on how you can capture this elusive green comet from the far reaches of our solar system. You can also view my experience in the video below. 

What is a Comet?

A comet is a small celestial object made up of ice, dust, and rocky particles that orbit the sun. They are believed to have formed at the birth of our solar system and are thought to contain some of the oldest and most primitive materials in the solar system.

The nucleus of a comet is often described as a “dirty snowball” due to its composition. When it approaches the Sun, the heat causes the ice to vaporize creating a bright coma around the nucleus and a visible tail.  This tail will always point away from the Sun due to the solar wind. 

Comet Tempel 1 after it obliterated Deep Impact’s impactor spacecraft. (NASA/JPL-Caltech/UMD).

Comet C/2022 E3 ZTF

This particular comet has a massive orbit, completing its path around the sun every 50 thousand years. The last time it was visible on earth was during the stone age, when there was absolutely zero light pollution to contend with!  

At the start of 2023, this comet traveled closest to the Sun. By February 1, it will be closest to Earth meaning there is still time to view this comet. In fact, on February 5, when it’s next to the bright star Capella, or February 9-13 when it’s near Mars, could be great chances to spot the comet. 

Astrophotography offers your best chance to see the tail of comet 2022 E3 and the green nucleus that glows with a green coma.

This graphic shows the massive 50,000-year orbit of Comet ZTF around the Sun. (The Sky Live).

How to see it?

If you’re in the northern hemisphere, you will have had the chance to see this comet since January 2023. But now that it has journeyed closest to Earth this month, there are still a few weeks of viewing before those in the southern hemisphere will have their chance to see it. 

It can be found in the area of the sky that is right near the north star, Polaris. Use your favorite astronomy app on your phone, like Stellarium, to guide you in the right direction. 

You will also want to use a pair of binoculars or a telescope to view this object as it is not bright enough to see with the naked eye. Ideally, you would view it without the bright glow of the moon interfering, but that’s precisely what I’ll be doing since there have been limited clear nights for me this winter. 

The path of Comet C/2022 E3 ZTF as it travels past Polaris in the night sky. Astronomy.com

My Approach

To capture the green comet I used a refractor telescope with a focal length of 550mm. This brings the comet in nice and close, but not close to avoid missing the tail, which luckily, was still there. That’s the exciting (and difficult) part about photographing comets – they are evolving, and unpredictable. The last comet I photographed was comet Neowise in 2020.  

I used a full-frame color camera, which utilizes the native focal length of this scope, to capture a nice big chuck of the sky in a single shot. I was able to see it right away through a test exposure, and then it’s a matter of choosing the ideal exposure time to reveal it without too much motion.

The comet is moving at a different speed and angle than the motion of the stars, so my standard method of sidereal tracking wouldn’t work. I’ve seen others use autoguiding on the comet itself (as if it were a star) with positive results.

I adjusted my exposure time to 60 seconds, to avoid too much motion in the comet in a single exposure. This resulted in a somewhat ’round” shape of the comet nucleus, with a slight amount of trailing when viewed up close. 

My Imaging Session

To run the image sequence on this comet I used a ZWO ASIAIR WiFi device to control the session. I can’t say enough about how great these little devices are.

It’s a powerful accessory capable of running a dedicated astronomy camera, guiding, and even autofocusing for those that want it all. I’ve recently switched to a bigger tablet to use the dedicated ASIAIR app, and it’s a treat seeing the huge preview images of the comet as they come through.

Although the WiFi range isn’t great, I can still control the imaging session just inside the garage to stay warm. The ASAIAR mounts directly to the finder scope bracket of my telescope and allows me to clean up all of the cables running to various devices.

I chose to use my Sky-Watcher Esprit 100 telescope as it has the perfect mid-range focal length (550mm) for an object of this size.  This model is included on my list of best astrophotography telescopes available in 2023.

In total, I captured 100 x 60-second tracked exposures centered on the comet. I utilized autoguiding for the stars to avoid star trailing and dithering between each frame (though it probably wasn’t necessary). 

I stacked the images in DeepSky Stacker using comet mode and stacked the images of the comet (not the stars) which created star trails in my final image.

My photo of Comet C/2022 E3 (ZTF)

I also created an animation of the comet moving across the star field, using the individual 60-second frames in a sequence. To do this, I simply converted the .FIT files to .jpg, and played the image frames in sequence using Adobe Premiere.

You can watch this animation in action in my video on YouTube. 

Comet Stacking

Both DeepSkyStacker and PixInsight (my go-to image stacking tools) offer a ‘comet stacking’ mode. They allow you to select the comet within the star field and stack the images in accordance with this point. 

I have not tried the PixInsight comet stacking tool yet, but for those interested, be sure to watch this helpful tutorial video by fellow astrophotographer and friend, Bray Falls. 

The process of stacking the comet in DeepSkyStacker involves manually selecting the comet in each sub-frame (which is a little tedious), and then choosing the ‘comet stacking’ mode in the stacking parameters (see below).

Be sure to locate the ‘comet’ tab within the stacking parameters window, and select ‘comet stacking’ if you wish to create an image like mine. This simple tutorial video may help.

Using the comet stacking mode in DeepSkyStacker.

The tool includes a ‘stars + comet’ mode, but it did not work for me on this project. A potential workaround for creating an image of a stacked comet without star trailing is to remove the stars from the comet image and place a background of tracked stars behind it.

Tips for Shooting the Comet

In terms of astrophotography-specific tips, I have a few things to keep in mind.

• Decide on your composition: You can either track the comet itself with a star-trailed background or capture the motion of the stars, and the comet will be blurred. As mentioned above, unlike a typical deep-sky object, they are moving independently from one another.
• Track the comet: For the ultimate portrait of this dirty snowball, you’ll definitely want your telescope to track the COMET – this will allow you to take a clear, long-exposure shot. You may want to stick to shorter subs tracking the stars and stack the image.
• Use the correct stacking mode: The stacking process is a bit different for comets and there are actually comet-stacking modes in both DeepSkyStacker and PixInsight. Try both to see which one delivers the best result.
• Get Creative: Many people like to create an animated timelapse of the comet traveling through the stars, which is a pretty cool effect because you can see how fast it’s actually moving through space. 

The bottom line is, once you’ve found it, the way you capture it is up to you. If you’re like me, just the whole idea of the event is fun – I don’t need to take the best photo out there.

Just remember, comets can be faint and difficult to see, so be patient. It will help if you let your eyes adjust to the darkness and use a star chart to help you locate it using the surrounding stars. 

Final Thoughts

Unlike some of the celestial events that get media attention, I think comets are a pretty big deal. They’re visitors from the far reaches of our solar system and they’re only here for a short period of time.

The fact that they’re (kind of) doing their own thing makes it cool. Whether it’s every 76 years or every 50,000, when they visit, it reminds us of our comparatively short lives here on our rock and how incredible this whole experience is.

So go outside and look for the green comet while you can, because nothing lasts forever. 

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A “hauntingly beautiful” shot of the Milky Way rising over the ruins of a Tudor mansion has won the top prize in a photography competition.

The image, taken by Richard Murray from Waterlooville, Hampshire, captures the night-time scene at Cowdray ruins in Midhurst and claimed the top prize in the South Downs National Park astrophotography competition, which attracted 60 entries.

In September 1793, while it was undergoing repairs and refurbishments for the impending marriage of the 8th Viscount Montague, a devastating fire destroyed most of the property, leaving the ruins that remain.

The competition celebrates the national park’s status as one of only 20 International Dark Sky Reserves in the world, which recognises the region as one of the best places globally to stargaze.

South Downs lead ranger Dan Oakley said of the winning image: “It’s such a well-framed image and shows what the landscape would have been like a couple of centuries ago.

“It’s a great little chocolate box photo of the South Downs.”

Mr Murray, who won a £100 prize, said: “We were blessed with crystal clear skies and I was lucky enough to be able to capture this shot of the Milky Way rising behind the Cowdray ruins.

“It demonstrates that you don’t have to travel too far from town to enjoy the spectacular dark skies the South Downs National Park has to offer.

“The national park has such a wide variety of beautiful landscapes and buildings to photograph and is truly a special part of the UK, both by day and night.”

Beachy Head moonrise by Andrew Parker (Image: Andrew Parker/ PA)

Runner-up in the main category, was a shot of the moon rising behind Beachy Head lighthouse, near Eastbourne taken by Andrew Parker, who won a £75 prize.

Mr Parker, who lives in south east London, said: “Despite travelling around the country to pursue my hobby of landscape and astrophotography I still go to the South Downs more than most other places. The skies around Birling Gap are fantastic.”

Story continues

The judges were also wowed by a photograph of a toad crossing a road near Cuckmere Haven, by Peter Brooks from Eastbourne.

The picture won the South Downs Nature at Night category and Mr Brooks received a £100 prize.

Toad In The Road by Peter Brooks (Image: Peter Brooks/ PA)

Mr Oakley said: “I like this image because it’s a bit different. It sums up the theme of ‘nature at night’ and really highlights the fragility of nature.”

Mr Brooks said: “I took this particular image to highlight the dangers toads face when migrating back to their breeding ponds.”

A crater that looks like a bear’s face has been captured on the surface of Mars by the HiRISE camera aboard the Mars Reconnaissance Orbiter (MRO). 

For the last 16 years, the MRO has been orbiting Mars in a mission to understand the history of the red planet. Previous missions have shown that, once upon a time,  water did flow across its surface, but it’s not clear how long for or whether it was long enough to sustain life. 

February could be one of the best months for astrophotography (opens in new tab) for 50,000 years. That’s because it should see the brightening of comet C/2022 E3 (ZHF), a long-period comet discovered last year that last visited in the Stone Age, around 50,000 years ago! That’s not unusual for a comet, and nor is it hyped up green color, but nevertheless the appearance of this icy visitor is something to get excited about for night sky images. 

Add a Jupiter-Moon conjunction, a brightening Venus after sunset and the rise of a full ‘Snow Moon’ and February 2023 has plenty to make going out in the cold seem like a good idea. 

February 2: Comet C/2022 E3 (ZHF)