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MESSAGE OF THE MONTH
Making good times with a DIY sundial
Thank you very much indeed for publishing Mary McIntyre’s instructions for making an equatorial sundial (DIY Astronomy, ‘Make a paper equatorial sundial’, August 2022 issue). The timing was perfect as I needed to occupy my granddaughter Akira on the first day of the summer holidays. It proved to be a tremendous learning exercise for both of us and we were delighted when the Sun came out just before Akira’s bedtime and correctly showed the time as almost 6pm GMT (7pm BST – or bedtime). The next job is to build a weatherproof version for the garden!
We’re delighted to see the sundial in action, Peter and Akira, and providing the timing for important points in the day like bedtime! It’s a great little project this one, easy to do and a fun activity for all ages. – Ed.
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
Number crunching
Thank you for all you are doing for a great and long-lived magazine. In July’s book reviews section, I was interested to read that author Antonio Padilla calculates the biggest number in the Universe to be 1061(review of Fantastic Numbers and Where to Find Them). In my forthcoming book on the history of Greek astronomy, A String of Pearls, I summarise Archimedes’s calculation of the size of the heliocentric Universe, and follow up by looking at this brilliant mathematician’s zest for exploring even larger numbers.
Not content with numbers restricted to the size of the Universe, Archimedes continued to construct a perfectly logical counting structure that soared way beyond human imagining until he finally decided to call a halt when he reached 1080,000,000,000,000,000(converted from Greek to our numeration)! A listing of Archimedes’s values for interplanetary distances has come down to us, but unfortunately through a garbled secondary source.
Mystery object
I was wondering if you could help me to identify something in the night sky on Friday 29 April at 23:07pm. I’ve tried to do my own research but nothing conclusive has materialised. It travelled south to north, looked like a small, spherical white full Moon, but was hazy in its appearance (its core was brighter). I tracked it from overhead until it disappeared below the horizon line. I was taking shots of the Heart and Soul Nebula and found out the following morning that this object passed right through one of the images. The photos were taken in Wales. I’ve seen and imaged many a shooting star and the ISS but never seen anything as large as this. Any ideas? Thanks.
This was the deorbit burn of a Russian Angara 1.2 rocket stage launched earlier that evening. Nice catch, Ian! – Ed.
Moving picture
I am puzzled and would be grateful if someone could answer a question for me. According to the television reports, the images that we have seen from the James Webb Space Telescope include some galaxies that are about 13 billion years old. I assume that these galaxies are not stationary and while the light from them has been travelling towards us, the galaxies themselves have moved and are thus today no longer where they appear to us to be. But if we are seeing them where they were shortly after the Big Bang then why are they all so far apart? Why aren’t they clustered together, relatively speaking, near to the centre of the event?
The current theory to explain why objects like galaxies were already so far apart so soon after the Big Bang is called Inflation. It proposes a period of immensely rapid, exponential expansion in the Universe during its first few moments. – Ed.
Tweet
Cath Adams @CathAdams1973 • Jul 19 @skyatnightmag I’ve been sitting outside stargazing, the air is cooler but sadly no breeze.
Here is the International Space Station passing over my house at 23:06 taken using @NightCapApp on an iPhone.
#InternationalSpaceStation
ON FACEBOOK
WE ASKED: what do you think of JWST’s new image of Stephan’s Quintet?
Tim Jardine A galaxy group I have viewed and imaged many times, but to see it like this is just amazing.
Jon Mcinerney You wait 13 billion years, and then five galaxies turn up at once.
Linda Wood Field I think it’s amazing and beyond comprehension.
Michael Page You get different information when viewing the Universe at different light wavelengths. Infrared light can pass through the gas and dust clouds that Hubble can see in visible light, so Webb allows the scientists to see the objects that are inside or behind those dust clouds.
Frank Michael Knight Game changing for the future of science. Truly stunning.
Lindy Lou Looks like part of a paw.
Peter Parr Gotta be intelligent life out there.
Jason Philip Hall Astonishing! Pure and simple. This instrument will change everything.
Ed Shendell Absolutely amazed at the images coming from the James Webb Telescope. Looking back in time 13.5 billion years ago! The impact this will have on locating lost luggage cannot be underestimated.
Room to grow
I have a question about the expanding Universe, which I haven’t seen an answer to yet. If the Universe is expanding, where is it expanding to? Is there something outside the Universe as well? Surely it cannot expand into nothingness. If there is something outside the Universe, is it possible that it’s another Universe?
We’re not entirely sure, but the leading idea is that it is expanding into dimensions we can’t perceive. Imagine a person living in two dimensions on the surface of a balloon that’s inflating – they can see the space around them getting larger, but not the third dimension it’s expanding into. – Ed.
Force fault
In the article ‘Jupiter’s Asteroid Swarms’ (July 2022 issue, Cutting Edge) it states that, “the gravitation of the Sun pulling in and the centrifugal force of our motion flinging out act to balance each other out”. As a physics graduate and teacher, I know that this statement is incorrect. There is no such thing as ‘centrifugal force’. Our planet stays in orbit due to the gravitational force towards the Sun providing the ‘centripetal’ force required for the Earth to follow its orbit. This force is not balanced by any other force, and indeed is an unbalanced force. If this force was not present, the Earth would merely continue in a straight line at a constant speed.
While centrifugal force is an ‘apparent’ force, which doesn’t actually exist like centripetal force does, astronomers use it as a common short-hand as it’s an easily understandable term. – Ed.
photoknoxy • 15 July
Another view of Wednesday’s rising full Moon (aka the ‘Buck Moon’ or supermoon) with the ruins of Mow Cop castle silhouetted in the foreground. #cheshire #fullmoon #moonrise #buckmoon #lunarphotography #nightsky #bbcnorthwest @bbcskyatnightmag @canonuk @nationaltrust @bbcnorthwest
SOCIETY IN FOCUS
York Astronomical society (YAS) was pleased to celebrate its 50th anniversary this year, and we’re looking forward to continuing our success with a series of events planned for this autumn.
YAS was founded in 1972 in response to the excitement generated by the Apollo programme. In April that year a group of observers from Stamford Bridge formed the society, initially meeting at their local pub or a garage belonging to one of the members. Later meetings were held at York Railway Institute, where two rooms with open coal fires and large tables were on offer. Discussions included the 10
November 1973 Mercury transit and Comet Kohoutek. One of our first observatories was in a derelict brick building, part of the abandoned hospital site on the edge of Acaster Aerodrome dating from WW2. We enjoyed camping there and using the old telescope, fortified by runs to the chip shop and the pub! In the last 50 years we’ve had six observatory sites and five different meeting places. Today we have an observatory at a farm east of York where we hold meetings and public events.
Extract from The Definitive History of the York Astronomical Society (So Far!), by Martin Dawson, yorkastro.org.uk
SCOPE DOCTOR
Our equipment specialist, Steve Richards, cures your optical ailments and technical maladies
Email your queries to scopedoctor@skyatnightmagazine.com
Should I insulate my observatory?
KEVIN PRIOR
Mitigating the effects of large temperature fluctuations to aid cooling down times and reduce the problems of dew formation are excellent reasons for installing an observatory. But a bare observatory won’t solve these issues completely, so it is worth making it as temperaturestable as possible.
Wooden roll-off-roof designs are much easier to insulate than metal or fibreglass domed observatories, and wood construction already offers an advantage in temperature stabilisation. However, there is an argument for not using additional insulation as this could lead to heat retention, which is radiated later in the day causing unwanted air currents that can spoil the view. You can avoid this by opening up the observatory earlier, in advance of an observing session.
For a roll-off-roof design, a combination of insulation and good ventilation is likely to be a good solution and a palecoloured (ideally white) domed observatory with good ventilation will also yield good results. Either solution will benefit greatly from the use of a desiccant dehumidifier.
Steve’s top tip
How do I set up a finderscope?
A finderscope is a small, wide-field scope that helps you find targets in the night sky. It should be firmly mounted to the main telescope tube, normally using a small dovetail bar.
Finderscopes should be accurately aligned with the telescope in two stages. Start by pointing the telescope at a distant object during the daytime (NOT the Sun), and centre it in the eyepiece. Next, without moving the telescope, centre the same object on the finderscope’s crosshairs by adjusting the three adjustment screws. To align at night, centre a bright star in your eyepiece, then centre the same star on the finderscope’s crosshairs using the screws on its mount.
Steve Richards is a keen astro imager and an astronomy equipment expert