Stargazey Pie December 2008
The December meeting took place at the end of a day troubled by wild and unpredictable weather. Starting off with snow in the morning, it then started to thaw, was rained on, and finally froze up in the evening, making conditions quite slippery. Still, many members braved the roads to come along to the meeting, where a talk on more extensive travel (Traipsing round the Universe) awaited, along with a specially prepared quiz! And it was worth the effort…
- HAS Office Bearers. All positions are up for grabs at the next AGM in April 2009. The Society is very keen to encourage and support members who seek nomination for the positions of Chairman, Secretary and Treasurer, as well as those wishing to serve on the Committee. Speaking of which, John Gilmour will be stepping down at the end of the year, so there will be a position there to be filled.
- Festive Frolics. The Society’s first Christmas Dinner will take place on Friday 12th December at The Anderson in Fortrose, 7:30pm. Apparently The Anderson has a very large range of Malt Whiskies, as well as several real ales, which should add to the festive spirit, and was voted one of the top ten restaurants in Scotland! Transport will be arranged for the Inverness townies who wish to attend. Cost is estimated to be between £30 and £35 for three courses inclusive of wine but will actually depend on what you choose to eat, as pricing will be individual. £10 deposit is due now, so please pass it on to Pat Escott or Simon Urry if you still have to pay it. Last chance to sign up!
- Observing. The observatory will be open for viewing on the following nights. Please note that events will be dependent on the weather, and you can contact the session hosts to find out if they will be going ahead. Further information on the sessions will be available on the Society website.
Session type Date Session Supervisor Contact no.
Public + members Fri 19th Maarten 07795 186530
Members only Sat 20th John Gilmour 07974 948278
The members’ session on Saturday 20th is intended to be a Christmas Star Party, with alcohol-free mulled wine, mince pies, nibbles, Rudolph steaks etc. As Eric said, it will be a chance to put the ‘party’ back in ‘star party’!
- Seeing Stars. ‘The Fishes Tale’ is by Pauline Macrae, and was published in the Friday 5th edition of the Inverness Courier. Curious about the title? Well we won’t keep you floundering for long – it can now be read here on our own website!
- Thank You! Maarten and the Committee would like to express heartfelt thanks to all the Society members who have helped out at various events over the last few months. These include the Highland Science Festival, which was a great success. One of the featured events, the World’s Shortest Physics Lecture, by Howie Firth, can now be seen on Youtube. Simply Google “shortest lecture” and you will see it for yourself. The video shows that the HSF was indeed open to everybody, and that they did indeed let absolutely anybody in…
Also, the Going Nova event was aided tremendously by the help of Society members. The event was a one-day affair this year, due partly to a lack of funding, so the help of the members was very greatly appreciated.
The bag-packing event at Tesco Extra was another way in which Society members went the extra mile, and a very small group of bag packers managed to raise the fantastic amount of £366.81 to go towards the Observatory funds. Fantastic job, everyone!
- Recycle. Old mobile phones and printer cartridges can be recycled, and in the process we can receive some funds to go towards the Society. If you have any of these lying around please bring them along to Eric Walker.
- Solar Eclipse Cruise. Forget about the Credit-Crunch: next year’s total eclipse will be the longest this century, with 6.5 minutes of totality. If there is sufficient interest the Society may organise a cruise trip. If you are interested you can find out more at http://www.eclipseofthecentury.com and put your name down on the information list at the next meeting. Prices start at just £1,395 per person, easily obtained by putting unwanted Christmas gifts/organs/children on Ebay!
- JSL Opening Day CD. The Society is offering a CD with about 200 photographs showing the building phase and opening day of the new JSL observatory. It also includes John Gilmour’s interview on the Highland Café radio programme, and copies of press and website articles. Cost is £5 each, funds to go to the running of the observatory.
- 4000 Years of Astronomy in The Highlands. This is the title of a mini-festival that we propose to run in March 2009 in conjunction with NTS at Culloden. We have received funding from the Highland 2007 Legacy Fund, which will allow us to stage this event and provide the club with some new supplies, including a new laptop computer!
- Refractor Available. John Gilmour has kindly donated a 60mm refractor to the Society, to be loaned out to members who would like to try using a telescope. Accessories and eyepieces are included, as are instructions and a case. It is stored at the JSL observatory between uses. Enquiries to any member of the Observatory Team.
- Next Meeting. In the past there has been a tradition of having the January meeting on the second Tuesday instead of the first, but no longer! In 2009 the first meeting of the year will take place on Tuesday 6th. The speaker will be Bill “I get everywhere” Leslie, asking, “Mars – How Did They Get It So Wrong?”
Pat Williams showed us some photographs that had been taken on the recent (Nov 15th) visit to the Royal Observatory, Edinburgh. About twenty members had gone on the trip, and were treated to a grand tour of the observatory site, including the huge rotating dome with 36” Cassegrain reflector telescope. Sadly, the telescope (made in 1928) was mothballed when it became too expensive to maintain. The observatory staff now develops cameras and telescopic equipment for other observatories and space missions.
The party was split into two groups, with one being guided by Alan Pickup (who has visited and spoken to the Society before) and the other by Russell Eberst. While one group was being shown the dome, the other was being treated to a visit to the Crawford Library, and then the groups swapped. The library contains many seminal works on astronomy and science, including first editions of Isaac Newton’s ‘Principia Methematica’ (imprinted by Samuel Pepys) and other titles. Despite some of these works dating back to the 13th century, several were lying open on display on desks, and we were allowed to take photographs of them (no flash allowed) or handle them (carefully) as we wished!
There was a gift shop too, with many interesting scientific knickknacks available for purchase, and several old telescopes on display in glass cases. Generally these were small refractors, often constructed from wood and brass, which had been used in the past and donated to the observatory.
The trip was a great day out, and was nicely finished off with a stop-off in Dunkeld on the way home for fish and chips! Thank you to everyone involved in the organisation of the trip, and to the staff at the ROE for making us so welcome on the day!
Highland Skies – December 2008
Could December be the best observing month of the year? I know we all look forward to the winter months in general, but for me December has a special appeal. Perhaps it’s the feeling that a holiday time is approaching and that the sky should somehow join in the festivities.
To some extent, it does. December is host month for the Geminids meteor shower, peaking on December 13th. Unfortunately, the Moon will be just past full, so will probably upstage all but the brightest meteors.
I read only recently that the Moon is actually hit by space debris, including meteors, at least once per month. Sometimes the projectiles can be about a foot long. When they impact the Moon, the resulting plume of lunar material can be bright enough to see from Earth with reasonably sized telescopes. Magnitude 7 is apparently common enough. Unfortunately, the resultant flare only lasts for a fraction of a second – half a second if you’re lucky, so you have to be looking in the right place at the right time!
When meteors reach the Earth, they first have to withstand the journey through our protective shield – our atmosphere. The small fragments burn up due to the friction of our atmosphere and larger ones are reduced in size. This means only very small fragments make it through – unless they were large enough to start with that they result in large crater-forming Earth-strikes, or devastating air-bursts, like at Tunguska in 1908.
The Moon does not have the protective shield of an atmosphere that Earth does, so anything that is on a collision course with it will strike the surface at full speed and without being reduced in size. On impact, they will create new craters, meaning that the face of the Moon (the far side too) is being changed before our very eyes!
When I first learned of this I found it fascinating. Apparently meteor showers present a higher likelihood of a lunar impact, as the Moon can easily be passing through the comet debris field that causes the majority of meteor showers, resulting in more strikes. Two things struck me (no pun intended) about this:
First, if the plans for a manned lunar base come to fruition, what protection will the lunar staff have against these interplanetary missiles? I’m sure that whatever the buildings are constructed from will not withstand being hit by an object travelling at 4500mph (that’s a slow one) with no atmosphere to slow it down or break it up!
Second, wouldn’t this be an ideal project for somebody interested in video astronomy, like Andrew Elliott who gave last month’s presentation? Being able to simply set up a camera to observe and record the Moon for a whole night and then play back the images when it was more convenient. Any impact plumes would be time/date marked for exact time placement, and the frames could be enhanced and/or shared with other interested parties.
Doing a Google search for “moon hit meteor” will yield a video on the NASA website, taken by Earth-based observers, of just such a 7th-magnitude, 0.4sec impact flare. Obviously a lot of people knew about this before I did! So, to increase the chances of actually seeing a lunar strike, you can either observe the Moon ‘live’ for every second that it is above the horizon, or set up a video camera and record it while you do other things. In the run up to Christmas I’m guessing that the second option would be the most practical. I suppose the tapes would make a good alternative to daytime television too…
The Main Event
‘Traipsing round The Universe’ by Maarten de Vries
Maarten is our interim Chairman and has been a longstanding Society member. His interest in the night sky was inspired by the chance viewing of a telescope in a shop window on his way to kindergarten one morning. Having studied Computing, Business Management and Engineering, Maarten found himself up here in the north of Scotland, and happened upon the HAS – which he promptly joined! As anybody who has met him will know, his enthusiasm is legendary.
Maarten started off by referring to a written work which visual observers have consulted for decades – Burnham’s Celestial Handbook, volumes one to three. The trilogy is a huge resource that covers thousands of celestial objects within the reach of amateur telescopes, and gives a wealth of information about each and every one. These books inspired his recent talk on globular clusters, and so too this talk, on motion within the universe.
Everything moves. The Earth rotates around its axis in just over 23h 56mins, and the galaxy that we live in also rotates about its centre. The period for this rotation (or the galactic ‘day’ if you like) is 250 million years! Yes, some of the numbers are going to be pretty big.
Stars are born in groups, or clusters, and eventually drift apart. Most stars are moving at somewhere around 20km/sec, and they usually move independently, but in the same general direction as others within the original cluster they formed in. As they progress, they can interact with such things as gas clouds, other stars, gravitational fields, etc. All of these can influence the way they move.
Although these speeds seem to be high to us, in universal terms they are quite low. We only detect the effect of stars moving if we watch them over very long periods of time. To demonstrate this, Maarten showed a video illustrating changes in the pattern of stars that makes up the asterism of the Plough over time. The asterism was virtually unrecognisable both at the beginning (many thousands of years ago) and at the end. Only here and now (give or take a few thousand years) does the group of stars make up the distinctive shape. The video also showed that the stars tended to drift in the same general direction, though by different amounts, which is logical, as they all started off in the same original star cluster (which is also thought to be the home of our own Sun).
The movement of stars was originally proven observationally hundreds of years ago. In 200BC Hyparchus catalogued the positions of 1080 stars. In 1718, Edmund Halley checked the real positions of some of those stars against the positions recorded by Hyparchus. They had moved up to half a degree from the stated positions! This is the equivalent of a full Moon’s diameter to observers here on Earth. At the same time, it was noted that the ‘real’ motion, or Proper Motion as it is called, of the bright star Sirius, was not in a straight line, but more of a slight zigzag. Thus, in detecting proper motion, the discovery of Sirius’s companion star was made. The work continued. In 1989, the Hipparchos satellite survey started, again noting the real positions of stars using parallax, but this time with an accuracy of 1 milliarcsecond – an extremely tiny angle, and not at all detectable by observers on Earth. Not surprisingly, this also revealed that the stars were still roving around the universe.
Not all stars move equally. The star known as Barnard’s Star, in the constellation of Ophiuchus, is moving towards out Sun at a speed of 140km/sec – seven times faster than the average! Another animation was shown that revealed how the star is moving across the surrounding star field at a visually discernible rate, covering the period from 1985 to 2000 – only fifteen years! The animation can be found here: http://www.solstation.com/stars/barnards.htm
Other stars found to be moving faster than usual include AE Aurigae, known as the Flaming Star in Auriga, 53 Arietis, and ? Colombae. These and many other stars are known as Runaway Stars, and these tend to be moving at hundreds of km/sec – much faster even than Barnard’s Star. Their motion may not be as noticeable to the amateur observer though, because the direction of travel may not be exactly perpendicular to Earth.
The Runaway Stars tend to be OB type stars, hot bright stars recently formed in star-forming clouds. Maarten produced a copy of the Hertzsprung-Russell diagram, and pointed out the position of the OB type stars, high up above the main sequence – burning fast and hot and living short lives.
As to how these stars become Runaways, Maarten told us about the two different processes that can create such phenomena. Both theories were developed by a Dutch scientist, Dr Ronni Hoogerwerf, working at the Leiden Observatory in the Netherlands. The Supernova Ejection Theory is the first such process. Most of the stars out in space have a companion, or sometimes more than one. When such a star goes supernova and explodes, it can literally ‘kick’ the companion star out and away at huge speed. The energy release in a supernova is extreme, so would quite easily be able to eject the companion out into space at an accelerated pace.
The second process, explained by the Dynamical Ejection Theory, is to do with direct interaction between stars or groups of stars travelling through space. We already know that stars are travelling independently through space, but what happens if one strays too close to another? Well, the gravitational forces can be enough to cause one of the stars to veer abruptly out into space on a different course and at a higher speed. The theory was originally applied to binary star examples. When two binary systems interact in this way, the result can be that one pair of stars get thrown apart.
So far Dr Hoogerwerf’s team have only examined 18 Runaway Stars, but the results so far are that two thirds seem to have been caused by Supernova Ejection, and one third by Dynamical Ejection.
Many of the Runaways have been traced back to OB associations. These are groups of type O and B stars that have formed within a small area of a giant molecular cloud. The type-O stars will burn out quickly, and erupt as supernovae after a million years or so, probably nudging the remaining type B stars (with lifespans of up to ten million years) out into space as they do so.
Although there is much more to say about stars travelling through space, there are other objects that are touring the universe as well, including open and globular clusters. M44 is a prime example of clusters in collision, as it seems to consist of two clusters, with the members of each one moving in different directions, through each other. Maarten then moved on to galaxies and talked about what happens as they travel through space and collide with each other. He showed as an example a picture of M82, which showed that its structure has been disrupted by interactions with nearby galaxy M81. The interaction has caused more gas to be transferred to M82, resulting in fresh star-birth areas. Could this be what the future holds in store for us?
The Andromeda galaxy, M31, and our own Milky Way galaxy are approaching each other at a combined velocity of between 100 and 140km/sec. ‘Collision time’ is in about 2.5 billion years – what will our skies be like then? Will there be massive gas clouds all around us? A huge number of naked-eye globular clusters? Star-birth regions being formed just a few light years away from us? And will we even be around to see any of it? One point Maarten did make was that although galaxies are vast and contain millions of stars, the chances of actual collisions between stars are surprisingly small. Our nearest stellar neighbour, after all, is Proxima Centauri, just over 4 light-years away! That’s a lot of space between stars for things to slip by each other.
The pictures Maarten showed and the explanations he offered all contributed to a brilliant talk about the to-ings and fro-ings taking place in the space all around us. We sometimes forget that everything is in motion, as it all seems to be unchanging in the day to day (or night to night) scheme of things. Only prolonged observation seems to show evidence of the motions that are actually taking place out there in the sky above.
Rhona Fraser was called to the front after the main talk and the raffle draw. Not to have her wrist slapped, but to receive her Messier Challenge certificates! Rhone has completed both the Bronze and Silver level challenges – well done Rhona! I sneaked a look at the certificates and they are very nice indeed.
So that is the incentive offered by the Society to complete the Messier Challenge sheets that have been available for a while now. They are available from our website on the Documents Library page under ‘Astronomy Projects’.
Members Recruitment Incentive Scheme
Finally, Maarten also explained about a new initiative that he and the Committee are working to develop. There have been many changes within the Society recently, including the completion of the new observatory and introduction of day trips etc. Maarten explained that perhaps we now need to take a step back and reflect on how best to utilise and implement these new achievements.
He is keen to encourage new memberships in the Society, and would like current members to be rewarded for encouraging their friends, work-mates and/or relatives to join. It is proposed that by successfully encouraging someone else to join, a current member may receive a discount on his or her next membership fee.
The benefit to the Society would be increased revenue, which will be required to run the observatory and to help provide the new services to members, but it would also hopefully provide an injection of new ideas and activity participants into the club. The final details for the incentive scheme have still to be worked out, so watch this space.
Next Time: The next meeting, the first of the New Year, will take place on Tuesday 6th Jan at the Green House, starting at 7.30pm. The Children’s group, “Youngstars” will meet from 7.00 to 7.30. The main event will be Bill Leslie’s talk on “Mars – How Did They Get It So Wrong” and there will be Breakout groups, tea, biscuits, chit-chat, and all the usual excitement and bustle!
In the meantime, clear dark winter skies to you all, and remember to drop by the message board if you see something or have a question to ask!