A nugget of purest green … ice!


Rob Nolan was thrilled to capture an image which, due to its orbit, we are potentially the only humans ever to have a chance to record

January usually feels like a long month for most of us, but for astronomers this particular one felt really long! We were blessed with a spate of crisp clear and moonless nights, so that meant not a lot of sleep for many of us, including me.
Those of you familiar with Blackadder, the 1980s TV show, may recall Lord Percy trying to create gold, and ending up with a ‘nugget of purest green’? Well I hoped last month that I would be able to share with you a very special once-in-a-lifetime capture of a green comet that has not passed our way for thousands of years.
As you can see opposite, I’m happy to say, I got it!
It really is a great feeling when you try to capture a rare target, those first images start coming in and you see the object for yourself in glorious detail.
Comet C/2022 E3 (ZTF) is a long-period comet from the Oort cloud and is approximately 1km in diameter. It was discovered as a very faint 17.3 magnitude smudge in the constellation of Aquilla, and the 1.2m telescope at Zwicky Transient Facility (ZTF) is credited with the comet’s discovery.
What is remarkable about this comet is that it last appeared in our skies 50,000 years ago, when Neanderthals roamed the Earth.
There’s talk in the science community about the comet currently moving in an open parabolic orbit; it may move into deep space and never pass this way again. This would mean we would be the only humans to have ever witnessed this comet in our skies with the ability to image it. Amazing!
C/2022 E3 passed within 26 million miles of Earth on 1st February, and should be visible as a faint smudge in the sky to those out looking for it well into mid-February – a pair of binoculars or a small telescope will help.
This image was captured with my 350mm refractor telescope and the ZWO ASI2600MM Pro Astro camera with RGB filters.
Only 30 minutes of capture time was needed to bring out the detail of the comet’s tail due to its apparent brightness.

The night sky, February 2023 – Rob’s guide for your stargazing this month:

Comet C/2022 E3 (ZTF) continues to grace our skies into February, having passed closest to the Earth on the first of the month and should be visible with the naked eye! It is visible near the north celestial pole and located within the Camelopardalis constellation.
Our local neighbours Venus, Mars and Jupiter continue to shine brightly in the evening skies throughout February, alongside some pretty high profile stars. The month ahead sees Orion drifting further west with the constellations Leo and Boötes continuing to rise higher in the east.
Canis Major, the larger of Orion’s hunting dogs, is in full view towards the East in the evening, crowned by the dog star Sirius, the brightest star in our night sky, hot on the heels of Lepus (the Hare).
Other nearby stars to take a look at are Mirzam – The Announcer in Arabic, due to the fact it rises just before Sirius – and Adhara which, five million years ago, held the crown for the brightest star in the night sky due to its relative position to the sun.
Nestled in Canis Major is M41, a relatively small star cluster of around 100 young stars. It is quite possibly the subject of the earliest known description of a deep-sky object, made by the Greek Philosopher Aristotle in 325 BC, though we can’t say for certain that this is what he referred to when he described ‘a cloudy spot’ in the constellation. You can observe M41 through binoculars or with the unaided eye.
I’m told Comet C/2022 E3 will appear to pass close to Mars on the night of the 11th, which would be a fantastic sight to behold, involving our local planetary neighbours dancing with the Moon in a neverending stellar waltz.
Other events to watch out for besides the comet?
On the 15th February, Venus appears close to Neptune, which will help stargazers find the outermost planet in our solar system. Find Venus, and then look to the lower right of the brightest planet to bring into view the dimmest. Compared side by side, Venus is 60,000 times brighter than Neptune.
On the 22nd, look west after sunset to see the crescent Moon adorned by Venus and Jupiter. The following night you’ll witness a similar entanglement, with Venus and Jupiter below the crescent Moon.
And since we have a short month in February, why not finish off on the 27th with a look at the Moon’s first quarter with Mars close by and the star Aldebaran shining brightly.
Until next time, clear skies!

Find Rob on Facebook as RPN Photography here


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