Stargazey Pie, March 2005
Antony McEwan's monthly digest of HAS happenings.
March 2005 meeting
This meeting was another very highly attended one and most seats were taken by the time the meeting started. The large attendance could easily have been due to expectations of another classy and highly charged talk/demonstration being given by Arthur Milnes. Indeed I did notice a lot of people wearing rubber footwear.
There were also rumours of a questionnaire floating about, and you know how a good meaty questionnaire boosts the attendances. Before we were able to enjoy these treats, there were even more juicy morsels in the form of the Society notices read by Chairwoman Pauline Macrae:
Pens- the conclusion Alan Mumford has received a new batch of red-light pens which were sent to replace the faulty ones of a few months ago. So, if you are expecting a replacement, please let Trina know at the next meeting. Any spares will also go up for sale again at that meeting.
Observing Sessions The last currently scheduled observing sessions for this season are as listed below. They will start at 8pm and finish around 11pm, depending on sky conditions. There is also a joint observing session with SIGMA, on Friday 8th April, which should also draw some members of the Aberdeen and District Astronomical Society, and some of the Falkirk Astronomers as well. The session will take place following a talk by Douglas Cooper about the Venus Transit as viewed from Egypt. Another session will take place on the 9th at SIGMA’s regular viewing site at Birnie. More details will be issued nearer the time, along with a map to find the viewing site.
Friday 11th March - Maarten de Vries
Saturday 12th March - Bill Jappy
Promethean Programme Radio 4, Tuesday 8th March at 9pm , is a programme about Project Prometheus. This is NASA’s research program which is looking at developing nuclear propulsion and nuclear power-generating systems, which it is hoped could one day power a manned mission to Mars, as well as other ambitious space missions. Sounds like a hot topic - could it even be a gift from the gods?
Scottish Astronomers’ Group Weekend Secretary Pat Williams informed us about the plans for this year’s SAG weekend event. The SAG was founded twenty years ago and exists as a means of keeping the many Scottish Astronomical Societies and clubs in touch with one another and enabling them to share ideas, observations and plans. To this end there are a number of SAG weekends held each year in different areas. This year the Highlands Astronomical Society will be doing its bit and helping to host one in Inverness. It will take place over the weekend of Friday 23rd to Sunday 25th September at the Thistle Hotel in Inverness. There will be an organised schedule of events which should cover Friday evening through to Sunday lunchtime. The Saturday afternoon is reserved for a trip to a local area of interest. If you can think of a good suggestion for this trip, please forward it to Pauline or Pat.
The cost depends on whether you wish to stay for the whole event at the Thistle Hotel, or attend as a day delegate. The price, if you stay exclusively at the Thistle Hotel, will be around £200, and prices for the other rates will follow. For those wishing other boarding arrangements, the local Travelodge has rooms available at £26 per night and is not very far from the Thistle.
If you particularly enjoyed Dr David Gavine’s recent talk about sundials, you may be pleased to hear that there will be a sundial enthusiast from Poland in Inverness this year. Perhaps he’ll be able to fix the one at Falcon Square…
More rubbish Pat also asked if the people attending the meetings could be more careful when disposing of their half empty tea and coffee cups. Unfortunately, the liquid leftovers that sometimes gets put into the normal bins can cause problems, and it would be appreciated if used cups could be left at the tea table, and those organising the teas and coffees will dispose of them properly. Many thanks.
Maarten’s wind of change I mentioned earlier the rumour of a questionnaire. Well that rumour was not unfounded, and this was proved when Maarten took the floor and had something to say about the evolution of the Society.
The last big questionnaire was presented in 2001 and it was really a big “What do you want us to do?” for the members to fill in. Many people responded and, as a result, the Society has changed a lot in the last few years. We have a larger and more technologically advanced meeting venue and the meetings can run on a bit longer, as we don’t have to be out the door at 9.30pm any longer. Many people said they wanted more observing sessions - well we now have an observatory and regular planned observing sessions through the dark seasons. We also have plans for an even bigger and better one in the near future - see below. Other people felt it important that we encouraged more young people into the society, and that has certainly happened. At this meeting, we had three young lads attending, and there are regular appearances from other youngsters. We even had a special meeting with two talks recently - one for adults and one for juniors. So you can see that these questionnaires are taken very seriously and really help to shape our Society.
Now we’re doing it again. The latest members' questionnaire is available and was handed out on Tuesday. Please take the time to fill it in and return it to Pat Williams at the address on the back of your programme. Alternatively you can bring it along to the next meeting on Tuesday, 5th April.
One of the points that Maarten made was that the Committee are always on the lookout for good ideas and the occasional helping hand. If you have an idea that you feel may improve the club, or are able to help out in any way, no matter how small, please mention it in the questionnaire, or even just tap a Committee member on the shoulder at a meeting and let them know. After all, it’s your astronomical society too.
A new observatory Next up was Andy Ferguson with an update on a proposed new observatory which will be built when the new Culloden Visitor Centre is completed. This ties in somewhat with the theme of change as it will mean some fundamental changes within the Society, but will yield some huge improvements in the long term. None of the required changes will have any adverse effect on the members and the Society will continue very much as-is, but with better observing facilities available.
The Jim Savage Lowden Observatory, as we now know it, was always intended to be a temporary arrangement, and has served us extremely well in that regard. The long-term plan was always to have a permanent, fully equipped, professional level observatory, and this now seems to be on the horizon. In order to achieve this aim, the Society requires:
· Changes to the Society's Constitution (to be ratified at the AGM in April)
· To attain Charitable Status
· To become a Limited Company
· Design of the new observatory to be agreed by the membership and accepted by the National Trust for Scotland and the Planning Department
· The help, support and commitment of the Society’s members
We also need some money. Andy showed us some provisional plans which seemed to fit in very nicely with the proposed new look Visitor Centre, and then started talking money. The estimated cost of the actual building is £38k and a further £14k to £56k is budgetted for furnishing the observatory with all the required equipment. So we’re looking at costs of up to £100k, which is not at all bad for a state of the art observatory in the 21st century. According to Andy’s budget, £100k would give us an observatory equipped with a 400mm Richey-Chretien telescope, a 7” apochromatic refractor, solar telescope, full computer control systems, CCD imaging equipment, audio-video equipment for presentations, an area suitable for smaller Society meetings, etc,, and many other high-end accessories (including a toilet).
Highlands Astronomical Society will be expected to partially fund this project, probably to the tune of approximately £5k to £10k. Members helping with the building effort will be seen as a ‘contribution in kind’, reducing the amount of actual cash input required. Some of the next steps to be undertaken include finding funding sources, signing a long-term lease with the National Trust for Scotland, and developing a descriptive information pack to be sent to potential funders. There’s a lot going on at the moment, and it will be interesting to see what changes have been made the next time we get a questionnaire….
Eyes On The Skies The Constellation of the Month was Virgo, which is just beginning to creep above the horizon in the evenings of March, and clears it by 11pm. Virgo is important for both planetary and deep sky observers at the moment, as it is currently the constellation of residence for Jupiter, as well as containing the impressive Coma-Virgo Cluster of galaxies. This supercluster contains some 2000 to 3000 galaxies, all approximately 55 million light years away. There are objects here for all sizes of telescopes, including some impressive ellipticals (M49, M60, M87), and spiral galaxies (M58, M61, M90).
Saturn is very high by the middle of the evening now, and is well away from the turbulent skies at the horizon. Take a look as it is giving absolutely stunning views at the moment in virtually any size of telescope. With the rings almost fully open it is a remarkable sight. Gradually, over the next few years, the angle of the rings will decrease until they are edge on to us and they will then briefly disappear from view. When that happens we may be able to discern more detail on the globe of the planet but for now we can enjoy the view from our ‘ringside’ seats.
Comet Machholz is now circumpolar, meaning that it does not set, and stays above the horizon at all times, circling the pole star. At magnitude 5.7, the comet is still easily visible in binoculars, but its brightness will fade through the month.
The traditional Winter constellations of Orion, Gemini and Leo are now almost reaching their highest altitude in the night sky, and as they move higher and further away from the horizon you should be able to see objects in these constellations with less atmospheric distortion present. Now would be an ideal time to have a look for the cluster M41 in Canis Major, discussed at the January meeting.
The Vernal Equinox occurs at 12:33 Universal Time on the 20th March, marking the beginning of spring. At this point the day and night periods are equal in length, but from then on the nights will be shorter than the daylight hours. Depressing? Yes, but I suppose there are people somewhere that actually like daylight so we can’t have it all our own way.
The Main Event March’s main presentation was delivered by Arthur Milnes and entitled ‘With a suitable system of gears and levers’. An intriguing title, but very appropriate, as will be seen.
Arthur has spent a great deal of his life in military and civil aviation, as a pilot, pilot instructor and flight examiner. Naturally, this meant that he had to be able to explain how the various gauges in a cockpit actually work - the altimeter, tachometer, air-speed indicator, etc. Although it was easy to draw and explain the function of those gauges, how they work was often much more complicated to explain, and so the phrase “by a suitable system of gears and levers” became a sort of verbal refuge for examiners and instructors.
So why was Arthur talking about aircraft cockpit gauges to a room full of astronomers? Well, there is a connection. Many gauges make use of gyroscopes. A gyroscope can be considered to be any heavy, balanced, rotating mass which is free to move. Ring any bells? The Earth can be considered to be such an object as it hangs physically unsupported in space and rotates about its polar axis. A property which gyroscopes exhibit, known as precession, also applies to the Earth.
You may recall that the polar axis of the Earth points very close to the star Polaris in the Northern hemisphere. That star is known as the pole star. Polaris will not always be the pole star though, and neither has it always been in the past. The line drawn towards Polaris along the Earth’s polar axis actually traces an ellipse across space over a period of 25,800 years, and so gradually moves away from Polaris before returning to it again in the far-off future. In approximately 12,000 years, Vega, in Lyra, will be the pole star, which will make it very easy to polar align telescopes, as it is so bright.
So, precession causes the Earth to move about slightly, or wobble in its polar orientation. Is this a big deal and what causes the precession in the first place?
Arthur had devised a demonstration of ‘precession at work’, and it required a swivel chair, a bicycle wheel and a willing (underpaid) volunteer. I say to you, I was that volunteer and I survived. Arthur seated himself on the swivel chair and held the wheel in front of him, perpendicular to the floor. He then gave the wheel a good spin so that it was spinning quite fast and freely on the hub. When I was asked to turn the swivel chair around, an odd thing happened. As the chair swivelled, the bicycle wheel actually ‘flipped’ over so it was now spinning parallel to the floor instead of perpendicular to it. This is how precession works, and it’s all Newton’s fault. It is to do with the conservation of angular momentum, which pops up in Newton’s laws of motion. In the demonstration, the action of swivelling the chair was applying an external force on the spinning object (the wheel), so how does that apply to the Earth?
Well, the Earth has a small amount of oblateness (flattening) at its poles, resulting in an extra 30 miles in its diameter at the equator compared to the polar diameter, and those 30 miles are acted upon by the gravity of the Sun and Moon. These gravitational forces act only to a small degree, but remorselessly and inexorably. Thus the force applied by external gravity is shunted at a right angle to the axis of rotation of the Earth, and precession occurs. It is a very long, slow process, but we know it’s real by observing that the pole star changes every now and then.
Arthur also explained that we see much more obvious examples of precession in everyday events. Aircraft used during the two world wars had a tail wheel. This was required because the propellers would be too long to rotate if the aircraft was horizontal, so it had to sit on the ground lower at the back than at the front. In order to take off safely though, the aircraft had to be levelled while under power. The pilot would do this by nosing down to raise the tail wheel off the ground. Unfortunately the big fast-spinning props at the front acted as massive gyroscopes, and as the pilot tilted the nose down the force would be precessed through 90 degrees into a force which would cause the aircraft to swerve violently to the side.
Helicopters operate by the very same ‘system of gears and levers’ and rely upon precession and its manipulation to actually fly. This is all very clever stuff and is harder to describe on paper (virtual paper?) than it was to understand Arthur’s expert explanation of this bizarre phenomenon.
A big thank you to Arthur Milnes for another entertaining and instructive talk, coming at a slight angle from the normal approach of astronomical talks. Overall I thought it was ‘wheelie’ good…
The next meeting is the AGM. It will be held on Tuesday 5th April, 7.30pm, at the Green House as usual. Come along to hear a thorough listing of our achievements over the last twelve months and please also return your questionnaires then.