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MESSAGE OF THE MONTH
Catching Saturn in a moonbeam
I was observing Saturn on the evening of Thursday 11 August with my girlfriend Lindsay. She’s not a serious astronomer but does take an interest in my hobby and loves taking photos of the Moon on her smartphone. She took several shots that evening and whilst most were so-so, one in particular stood out. The ‘moonbeam’ in the shot could not have been better aimed to point out Saturn, above left of the rising Moon! Right place at the right time, we think.
A wonderfully serendipitous shot of Saturn, Tony, which has put Van Morrison’s song ‘Moondance’ in our heads!
This month’s top prize: two Philip’s titles
The ‘Message of the Month’ writer will receive a bundle of two top titles courtesy of astronomy publisher Philip’s: Nigel Henbest’s Stargazing 2022 and Robin Scagell’s Guide to the Northern Constellations
Winner’s details will be passed on to Octopus Publishing to fulfil the prize
Size matters
I enjoyed your feature ‘From city lights to deep space’ (July 2022). In it, it’s mentioned that certain star clusters and other deep-sky objects can be seen using telescopes of a certain size, but it doesn’t mention what type of telescope, whether it’s a reflector or a refractor. It may be helpful if both sizes are mentioned. I know scopes vary, but it could be a good guide. Telescope sizes are often mentioned in the magazine, but again not the type.
Where we have space, we will mention the type of telescope and its aperture. You’ll also find a guide to equivalent sizes of refractors and reflectors in the ‘Need to know’ column in the Sky Guide of every issue. In the case of the feature you mention, Bill, we meant refractors!
Shift happens
As the light from distant stars has a redshift, does this mean that the infrared signature of a gas observed for an object with a redshift has its signature redshifted too?
That’s right, David, all the light from distant stars gets redshifted, meaning that visible becomes infrared, infrared becomes radio and so on, which is why radio telescopes like ALMA are so good for seeing distant galaxies.
Photo op
In his letter in your September issue, Ian Sutton mentioned a mystery object he observed on 29 April, which you identified as the deorbit burn of a Russian rocket. I saw it too, ‘hovering’ above our house as I went outside to check my DSLR that I had left meteor-hunting. It looked just like a globular cluster, but I knew it was far brighter than M13 or M22. I would have got better images with my 75–300mm zoom lens, but all I could do was divert my camera as was (with a 18mm lens, ISO 6400 and six-second exposure) towards it. The image (below) shows a blue patch to the lower left, the blue colour not being apparent visually.
Sky streaks
I live near Basel in Switzerland and on Saturday 20 August I was able to take photos and a video of SpaceX’s Starlink satellites passing in space.
Sun seekers
Under clear blue skies on Thursday 11 August members of Sunderland Astronomical Society set up their scopes for a solar observing event at Northumberland Park, North Shields, Tyne and Wear, and park-goers were able to safely observe our nearest star. Many were surprised at what they were seeing for the first time, marvelling at the sunspots and solar prominences that were on view. More than 100 people attended the event, 34 of those were children, and there was lots of enthusiasm and loads of questions. It was a lovely day and a novel way to celebrate the park’s 137th birthday!
Tweet
Barry Clough @CloughBarry • Aug 22
Stepped outside at 5 this morning, the Moon above me, Venus shining low between the houses and Jupiter with its moons at a steep angle. Another trying day ahead made easier with such sights! @skyatnightmag
ON FACEBOOK
WE ASKED: What would you like to observe or image before the end of the year?
Matthew Terrell I’d like to be able to get enough images to show the rotation of Jupiter over a night, then turn it into a GIF showing the rotation of the planet and its moons. Fingers crossed.
Debz Townsend I’m aiming for Mars – Olympus Mons – using my Celestron NexStar 8SE telescope and new Barlow lens.
Bob Kelly I’m just looking forward to seeing the bright planets (well, Mars, Jupiter and Saturn) in the evening sky. Easier to get at as night starts to arrive earlier.
Brian Smale Anything in focus after getting my telescope properly collimated.
Mick Cassidy Planets when available and, of course, the ‘Deep-sky tour’ in every edition of the magazine.
What’s the holdup?
Why are there specific windows for Moon launches? Surely the Moon is above us a lot of the time. After the Artemis launch was called off on Monday 29 August the next window was Friday 2 September. But the Moon moves more by Friday than it will on the days in between, so why isn’t there a window of opportunity on Tuesday, Wednesday or Thursday?
There are several factors considered for an Artemis launch window. The three main ones are: first, the alignment of Earth and the Moon has to put the Moon within reach of the rocket’s performance; second, for thermal reasons and solar power production, the Orion crew capsule can’t spend more than 90 minutes in eclipse; and third, Orion has to splashdown in daylight. Not all of these requirements will be met every day, hence the limited number of launch windows.
aman_chokshi • 22 August
The first light of dawn at the South Pole! A spherical panorama with the @nsfgov Amundsen-Scott station on top with brilliant auroras on the bottom. A bittersweet moment to be losing these breathtaking night skies, but looking forward to a magical transition to sunrise. @bbcskyatnightmag @youresa @universetoday @nsfgov @nature
SOCIETY IN FOCUS
With the new observing season upon us, what better time to take your interest in the night sky further and join an astronomical society? Coventry and Warwickshire Astronomical Society (CAWAS) meets on the second Friday of every month at Coventry’s Earlsdon Methodist Church at 7.15pm. Meetings begin with a welcome from chairman John Davis, followed by Sky Notes, a review of events in the month ahead, the latest astro images from members, Hubble and the James Webb Space Telescope, plus news of what’s coming up in the night sky. This is presented by our resident galactic hitchhiker, Mark Edwards. After a refreshment break, the evening concludes with a lecture from a visiting speaker or a member. In October we’ll be looking at the Big Bang theory and in November we’ll focus on planetary nebulae. We also offer members advice on equipment choices. We look forward to seeing you!
SCOPE DOCTOR
Our equipment specialist, Steve Richards, cures your optical ailments and technical maladies
Email your queries to scopedoctor@skyatnightmagazine.com
I use my Sky-Watcher Evostar 100ED reflector with a 2-inch star diagonal, a binoviewer and a William Optics 9mm eyepiece, but when I try to find the Moon I can’t see anything. Help!
ANDY PARRETT
A binoviewer increases the light path between the focuser and your eye, which must be compensated for by racking the focuser inwards. Unfortunately, the Sky-Watcher Evostar 100ED is not binoviewer-friendly and the most likely problem is that you are unable to move the focuser in far enough to achieve focus.
There are a few things you can do that might allow you to use the binoviewer with your reflector, all of which are designed to reduce the light path length. Try a 1.25-inch mirror star diagonal instead of your current 2-inch diagonal, and ensure that the two eyepiece focus tubes on the binoviewer are racked fully in. You could also attach the supplied Barlow lens to the binoviewer’s nosepiece, as this will reduce the light path length – however, this will increase the magnification of the view.
If none of these resolve the issue, then replacing the existing focuser with a lower-profile design like the Baader SteelTrack Diamond RT for Refractors may work.
Steve’s top tip
What is coma and how do I fix it?
Coma is an optical aberration that occurs predominately in parabolic reflectors and manifests itself as ‘comet-shaped’ stars, with their heads pointing inwards towards the centre of the field of view. Although rarely an issue when observing through an eyepiece, coma can become intrusive in images, especially those captured with a large sensor. Coma also becomes more obvious in shorter focal length telescopes and increases with distance from the centre of the mirror, as the aberration affects off-axis light.
Luckily, a coma corrector that fits inside the focus tube will largely correct the aberration.