Stargazey Pie August 2006
It’s said that into every life a little rain must fall. Well it certainly fell into all our lives on Tuesday 1st August! After such a long run of hot dry weather the heavens opened. (Of course this can usually be taken as a sign that somebody’s been buying new astronomy kit.) But it is also said that every cloud has a silver lining, and Tuesday’s was the meeting of the Highland Astronomical Society in the evening. On the agenda were a very timely talk on Noctilucent Clouds, informative and entertaining breakout sessions, and of course the month’s notices:
- It’s a Sign! Yes it is indeed a sign, and it asks that only those attending the HAS meeting use the Green House car park on nights when those meetings take place. Thanks to John Gilmour for that.
- Life on Mars (again). Mark Sims, the mission manager for the ill-fated Beagle 2 lander, has been in touch to let us know that he is now working on the ESA Mars Lander Mission. He sends his regards to the Society, and we in turn would like to wish him the very best of luck in this new project.
- 1+1=? Thanks were expressed to yours truly (shucks) for donating a Large Calculator for use in the observatory. Easy to read in the dark, it is hoped it will be useful for astronomical calculations (big sums) on observing nights. Plans for the follow up Very Large Calculator are in the pipeline… I also received thanks for maintaining the Society’s website, but I’d like to share those thanks with the other members of the Media Sub-Committee, who provide me with a lot of help and support; Maarten, Pauline and Eric. Maarten stunned us all with the news that over the last month the site received more than 1000 visitors per day! www.spacegazer.com is where it’s all happening.
- A Big Book. A copy of the Astronomical Encyclopaedia, published by Canopus Publishing, was available for people to look at and place orders for. It usually sells for £40 but is being offered to astronomy clubs for £30, or if two or more copies are ordered just £25 per copy. Published in 2004 it is a British work, and is very nicely presented. Details are available from Pauline if you are interested.
- The Road to Morocco. Ancient World Tours Ltd are offering a trip to Morocco to view the Leonid meteor shower this year. The company organises tours for special interest groups, but we cannot endorse this company, as we have no experience of using them. If you decide to go, it will be at your own risk- though we’d welcome a report when (or if) you return! It is not known whether the tour guides are Dorothy Lamour look-alikes.
- Observing Evenings. August is the month of the Perseid meteor shower and we intend to have viewing sessions at the Culloden observatory to see them. The sessions will start at 10pm, but as always will be weather-dependant, so contact the session hosts if you are in any doubt about whether they will take place. Contact details are as below:
Friday 11th August......Pauline Macrae
Saturday 12th August....David Hughes
- New Observatory. We are in the process of producing a brochure about the proposed new observatory. This will be sent with a letter to local businesses to see if they would be interested in making a contribution to the funds needed, in exchange for a plaque inside the observatory commemorating their involvement. Can you think of any local businesses that may be interested? Members will also be able to take advantage of this offer, and the plaques will be offered to members at just £25 each. Free advertising on the Society’s website is also being considered as an incentive to businesses to become involved. We are also open to any other fund-raising ideas you may have, so feel free to discuss them with a Committee member.
- For Sale! Observatory- fully functional rotating shed type with sliding roof section and stable-door allowing easy access to all sky areas. All electrics (including solar panels) included and many accessories too! Yes, the Highlands Astronomical Society’s current observatory is now available for you to own. If you are interested, or for more details, please contact Pauline or Arthur. Note that the telescope (Orion 10” f5 Newtonian on Vixen 2000 computerised mount) can be included at your option.
- Volunteers Needed. We would like some volunteers please, to help at two public events in September. The first is ‘Yourinverness’, on Sat 9th Sept at the Inverness Leisure Centre from 10am – 4pm. A number of local clubs and societies will be promoting themselves at this event so it should be a very interesting day. If you could help out, even if only for an hour or two, it would be greatly appreciated. The second event is the annual HAS Open Day in the Eastgate Centre, which will take place on Sat 23rd Sept from 10.30am – 3.30pm. This event has been a great success in the past, and again any amount of help will be appreciated. If you can bring along a telescope to display (to either event) then so much the better. There will be a public viewing session at the observatory on the evening of the Open Day. If you are interested in coming along or volunteering to help, please contact Pat Williams.
- Dundee 50th. Dundee Astronomical Society is celebrating its 50th anniversary on Friday 15th Sept with a public lecture, to which we have all been invited. The subject of the talk is not known, but it will be given by the Astronomer Royal for Scotland, Professor John Brown. It is not known whether the Magic Circle will be supplying extra security to protect their secrets. (Professor Brown is known to include magic tricks in his lectures, keeping us on the edge of our seats at all times!)
- Computers Are Evil! You may be experiencing problems contacting Pauline by email. This is because her machine is currently undergoing repair. You’ve all seen the advert where the woman throws her computer out of the window? Well, I gather it was nothing like that! My computer is only just back up and running after also being broken, so please have patience if you do not get instant replies, or consider using the good old telephone as a temporary measure. Normal service will be resumed shortly- please do not adjust your set.
- Membership. This is just a reminder to point out that membership entitles you to be included on the telephone contact list, and to receive copies of Stargazey Pie when you miss meetings. Membership lists will be being reviewed very soon, so if you are intending to rejoin please submit payment as soon as possible, or you may miss out on these membership features. Also, if your email address or any other details have changed, please advise Pat Williams so we can keep our records accurate. Thank you.
The Main Event
‘Noctilucent Clouds – A Modern Phenomenon?’ by Ken Kennedy
Ken Kennedy started observing in 1958 when he joined the fledgling Dundee Astronomical Society (see notices above), of which he is now the Treasurer. He also serves as Assistant Director of the British Astronomical Association Aurora Section, and has a special interest in Noctilucent Clouds (NLCs). Ken is an official Astronomer at the Dundee Mills Observatory, along with Bill Sampson, and regularly gives talks there. He can be contacted by email here.
Ken started by pointing out that NLCs are still quite enigmatic. There is a lot we don’t know about them, and they are a phenomenon that amateur astronomers can greatly increase knowledge of by regularly looking for them and reporting their observations.
Aurorae, on the other hand, have been recorded from very early times (although not always scientifically accurately) and so they are well known to most of society. NLCs however are very rarely mentioned historically, and in fact never before the eruption of Krakatoa in 1883. The first reported observation was made in 1884 and reports appear sporadically thereafter. As an example, Thomas Romney reported seeing strange luminous clouds in the northern sky that were not auroral in nature when he was at the Armagh Observatory in 1850.
Where do NLCs form? They are best seen from latitudes between 50 and 65 degrees in the northern or southern hemispheres. Naturally, most observations take place in the northern hemisphere, as there is relatively little inhabited landmass at the right latitudes in the south.
They only show when the Sun is more than 6 degrees below the horizon. This allows the Sun to illuminate the particles that form the clouds. These particles seem to accumulate very high in the mesosphere, at about 86km to 87km high. The particles are very small- only about the same size as single red blood cells! It is thought that they could be water vapour particles that have risen through the atmosphere below. At this very high altitude the particles freeze and then drop back down slightly to a height of about 82km to 84km. At this height they are visible, and form the strange and intricate structures that we know as Noctilucent Clouds.
The time frame when NLCs are visible each year is from May through to early August, but not within a week or so on either side of midsummer- at least not at this latitude, as the Sun is not far enough below the horizon at that time to let them be seen. Further south they may still be seen at these times.
They generally form to the north and may extend to the east and west from there. Beware of confusing other types of clouds with NLCs, which can easily be done by the beginner. It is possible to differentiate between them, as normal weather clouds will darken as the Sun sets, while the NLCs will develop their unusual wispy structures and will appear light when compared with the background sky.
The structures they form are separated into different types. Type I are veils, II are bands, III are waves and IV are whirls. Examples of these types and further subdivisions can be seen on the Noctilucent Cloud Observers website. The brightness of the forms is also graduated from 1 (barely visible against background sky) to 5 (noticeably illuminating objects facing it) and continued observation of NLCs will enable you to readily appreciate the different structures, shapes and brightnesses within displays.
Ken is very keen for observations of NLCs to be reported to him. You can email reports to him at the email address listed above. Some basic information is required, including:
- Observer’s location, time and date (expressed as for example 14th/15th, 16th/17th rather than just the single date). This is the only required piece of information. The following are also useful, though not essential.
- Direction in which display appears (and extent to which it extends east and west)
- Highest elevation of display, expressed as degrees above horizon.
- Lowest elevation of display, expressed as degrees above horizon.
Angles of elevation can be measured simply by using your fingers or hands at arms length. One finger width equals 1 degree, a thumb’s width equals 2 degrees, and a clenched fist equals 10 degrees. These are approximate measurements but they will be accurate enough. Any further information supplied about sky conditions or weather is also considered useful, as are negative reports; that is, reports of no NLC forming despite conditions being apparently right for them.
Sketches are also very helpful, and as Ken said, can sometimes convey much more information than mere words can. Photographs also, although settings for different cameras will vary and it may take some experimentation to decide which settings are best for your camera and circumstances. More advice on this is given on the NLC Observers website.
This year has been a remarkable NLC season, with long runs of consecutive nights showing displays visible to observers all over Europe. Ken showed some photographs he had taken this year, and of particular interest was one which was taken on the night of 14th/15th July and showed a fantastic display- one which observers at the Culloden observatory (myself included) had been witness to while observing Jupiter!
Further study of NLCs is required to answer questions like, “Are NLCs being seen at lower latitudes than before?” and “Are NLCs seen as a virtual barometer for global warming effects?” Hopefully, HAS members can now contribute to observations of this strange and beautiful phenomenon. NLCs were also featured in July’s Seeing Stars article in the Inverness Courier, written by Pauline Macrae, and available here to read online. Click here to see a selection of photographs on the Spacegazer Image Gallery.
We would like to thank Ken for opening our eyes to this wonderful summer sky show, explaining some of the mysteries of NLCs to us, and inspiring us to look at them just a little bit harder. A reason to go out under warm summer skies is always appreciated!
Eyes on the Skies.
Throughout August we will notice the night sky getting gradually darker, and slowly more and more stars will begin to appear each night. The next observing season is just around the corner and we can start to look forward to catching up with our favourite celestial objects again, or perhaps hunting down some new ones. Yes, this is an exciting time of year!
As mentioned in the Notices above, the Perseid meteor shower peaks on 12th August at 23:00 Universal Time (UT). For several nights before and after this time we should hopefully see numerous swift, bright meteors originating from the radiant, which lies close to the stars Eta and Gamma Perseii. No optical aid is required to watch meteor showers, so it can be a very relaxing and easy to do astronomy project. We will be at the Culloden observatory hoping for clear skies to let us see some whizzing dust fragments skipping through our atmosphere, but unfortunately the time when the numbers increase to their maximum will coincide with the rising of the waning Moon. This will probably reduce the number of meteors we will be able to see, but I’m sure there will still be many noticeable ones to spot. We won’t know until we try, so feel free to come along to see one of the classic summer meteor showers, but remember to bring your deckchair and something warm to wear as the night draws on.
Later in the month, the Moon passes close by Jupiter on the 29th at 22:00 UT, and should be another nice photo opportunity for those wanting to capture another lunar / planetary conjunction. It should also be a nice view in a wide field telescope.
It is also time to start looking for good dark sky observing sites with low southern horizons. Why? Because we need very low horizons to be able to see anything of the deep sky treasures of the wonderful constellation Sagittarious, and the time to prepare is now. The latest Seeing Stars article includes information about some of these treasures, and was written by Maarten de Vries. It will be uploaded onto the Spacegazer website in the next few days.
So, if you’re not watching meteors, NLCs or planetary / lunar conjunctions you could be exploring your neighbourhood for a good observing site and making sure that your telescope is in tip top condition for the coming dark sky season. And just think- you’ll soon be able to try out all the new equipment you bought over the summer (or is that just me?)
Next Time. We welcome Dave Gavine back to the Highlands next month, in anticipation of his talk on ‘David Nasmyth and his Telescopes’. This will take place on Tuesday 5th September at the Green House, starting 7.30pm. September is a busy month, what with the Open Day and Yourinverness public events, more mention of which will be made at the meeting. (See notices if you require more information on these events or to volunteer).
The usual Breakout groups will also take place, along with the ever-popular prize raffle, which is really helping to bring in some extra (much-needed) funds. Until then, keep your eyes peeled, enjoy the darkening skies, and remember to pop in to the Spacegazer message board or events page from time to time for the latest information.
See you in September!