Stargazey Pie March 2008
The March 2008 meeting of the Highlands Astronomical Society took place at the new NTS Culloden Visitor Centre. This was in order to sample their facilities, with a view to deciding whether to have our monthly meetings there in the future, or remain at the Green House. There was a large turnout, so lots of feedback! The attendees also got to enjoy a splendid talk by Neil Bone on Meteors, receive updates on the progress of the Society’s projects, and enjoy a new observing spot presented by Bill Leslie. Before all that, the notices were read by Secretary Eric Walker:
- Immortality Still Available. Your low-price Immortality special offer is still available, but time is running out! Contact Pat Escott to arrange a donation of £25 towards observatory funds in exchange for a place on the observatory plaque. Renown and popularity guaranteed.*
- Moon-phase Postcards. ‘Moon-burn’ is a serious condition, but is easy to avoid. Simply buy a moon-phase postcard for £1 from Pat Escott and you will know when it’s safe to go out at night and when you will need to apply protective moon-cream to keep the lunar rays at bay. Only a few left so please contact Pat to reserve yours now! **
- Seeing Stars. Pauline Macrae has written the latest Seeing Stars article, entitled ‘The Twins and The Charioteer’ for publication in Friday 7th’s edition of The Inverness Courier. It will also be uploaded onto our website a few days after that.
- AGM. The AGM will take place at the next meeting, April 1st at the Green House. A DVD will follow the ‘serious bits’. Please come along – your vote may be needed for something!
- 2009 HAS Calendar Astrophotography Competition. This year we will be holding a competition to select the astrophotographs for inclusion in the 2009 HAS calendar. The competition will be judged by HAS members and will feature some exciting prizes for the winners. Eric has kindly agreed to run a series of workshops for members interested in developing their photographic and image processing skills over the next few months. These are likely to be held in the new observatory at times suitable for participants and trainer. If you are interested in registering, please contact Eric.
- Strathnairn Community Woodland (Farr) Dark Skies Event. Thanks to everyone who helped out; Marion Porteus, John Gilmour, Donald Boyd, Pauline Macrae and, of course, the inimitable Bill Leslie who always does so much for these events.
- Heather Connie Martin “The Lost Language of the Stars”. The origins of carved Pictish stone symbols, an ancient and now forgotten system of constellations. An approval copy of this new book was available for perusal at the interval (and probably next month too) and there is an ordering form to complete if you are interested in purchasing a copy. Price still to be confirmed (but definitely not as cheap as a moon-phase postcard).
- Richard Dawkins. Richard Dawkins, author and scientific speaker, will be at Eden Court on Wednesday 2nd April. The evolutionary biologist will be in conversation on stage, and will answer questions from the audience. Contact Eden Court for more details.
- Café Scientifique. Interested in an informal scientific discussion group with coffee and conversation? Contact John Gilmour if so, and he’ll clue you in to a possible group meeting somewhere cosy in Inverness. Jazz optional.
- Monthly Astronomical Events: Saturn: well-placed all month; Galaxy fields of Leo & Virgo: all month; New Moon: Fri 07 Mar; Spring (vernal) equinox: Fri 21 Mar; Photo opportunity (crescent Moon & Pleiades): Wed 12 Mar: from twilight onwards; BST begins: Sun 30 Mar, doesn’t get dark until about 9pm and rapidly gets later & later!
One further notice was that SAG (The Scottish Astronomers Group) is changing its role in Scottish astronomy. Tim Schroder gave us some information about this, having attended many SAG events and being familiar with the group.
The SAG was originally the brainchild of Dave Gavine, who started it as an informal group who would meet to observe the sky and discuss their observations. In the ensuing years it has become a large umbrella organisation for other, smaller, Scottish astronomy clubs and groups. In order to receive the benefits of SAG membership, individual clubs had to pay membership fees. As a result there are still some monies to be dealt with, and Tim has volunteered to help out with that duty.
Recently the SAG began to run into problems maintaining that role – it was simply too big to continue in that way, and it was proposed that it be wound down. It is suggested that it will revert to its original role as an informal forum for Scottish observers.
Tim’s opinion was that it is better to actually get out and about and meet people from other societies, and get involved with shared activities, rather than spend time on an online impersonal Internet forum. He told us that the SAG events he had attended had always been very popular and exciting. Maybe some of you reading this can remember the time Inverness hosted the SAG weekend in Inverness? Tim also took the time to point out that events such as Astrofest (as mentioned by Pat Williams) are a tremendous way to meet members of other clubs and societies and to pick up ideas from them.
Thanks to Tim for sharing a little of the history of the Scottish Astronomers Group, and for letting us know about the intended changes for the future.
Pat Williams took the floor with a report on her adventures at Astrofest in London in February. Astrofest is the UK’s premier commercial festival of astronomy, and is a weekend of total astronomical overload that takes place at Kensington Town Hall. There are 16 lectures spread over two days, and in between them you can browse dozens of astronomy related stalls! There are many bargains to be picked up at these stalls, and many of the UK’s astronomical retailers take a selection of their stock to the show and offer big discounts.
One of the stalls that Pat spotted belonged to one of HAS’s members! Jeremy and Simon Rundle - possibly our most distant members - manned the S.T.A.R. Distribution stall! The company offers memorabilia authorised and personalised by Sir Patrick Moore. Sir Patrick was also present at the show, as were Alan Chapman, David Levy, and many other ‘star’ names in astronomy!
Pat showed us some pictures she took while at the show, including some of her co-attendees Pat Escott and Linda Moncur, and Jeremy Rundle in action at his stall. The show always takes place on either the first or second weekend in February, and is promoted by Astronomy Now magazine, who advertise the event details and tickets from November onwards. Naturally, Pat highly recommended the event and really sold it to us as an exciting and enjoyable event to attend.
The intrepid traveller closed her presentation with a superb picture of the Moon shining above Kensington Town Hall on one of the evenings. Unfortunately the Moon happened to be just outside the frame so was entirely invisible, but it’s the thought that counts!
John Gilmour gave us another update on the progress of the new observatory, situated just a few hundred yards away from where we were sitting! A series of photographs was shown that portrayed the progress over the last several weeks, and it’s really coming on fast now! The photo’s can be seen on the Progress Page on our Society website.
One minor problem has reared its head, that being the fact that the fire-retardant finish we hoped to use on the wood of the buildings is actually unsuitable to apply to the exterior. This only came out recently, contrary to original advice by the suppliers. This means the timber has to be sent away to be treated instead, adding about 6-8 weeks to the building process, and an additional cost of £795.
Unfortunately this may impact on our provisional opening date of 20th April, but more information will hopefully be available by the next meeting.
What the Members Want
Some more results from the recent questionnaire were presented by John:
- 1st place, 22 votes: Astronomy Trips
- =2nd place, 18 votes: Introduce a children’s subgroup
- =2nd place, 18 votes: Set up BAA style subgroups
- 4th place, 17 votes: More star parties
- 5th place, 15 votes: Set up telescope club/equipment group
- 6th place, 13 votes: Regular public opening of new observatory
- 7th place, 12votes: Christmas Dinner
In response to this, a proposed itinerary for a 2009 two-week trip to Arizona is available. Please contact John Gilmour or Andy Ferguson if you are interested. Alternative trips are also on the cards – more details will be announced when available.
There is a list of different types of BAA-style subgroups. If you are interested in joining one of these specialist subgroups, please put your name down on the appropriate list(s). John or Eric will do it for you if you wish.
Weather permitting, the new JSL Observatory will be open every Friday evening from October through to March for public observing!
A new Telescope Club and Equipment Group will also operate on Friday evenings at the new observatory.
Star Parties will be arranged at the new observatory and at other suitable venues.
Further developments will be announced soon with respect to astrophotgraphy workshops, a Children’s subgroup and the Christmas Dinner.
So far the votes for keeping the meetings on Tuesdays number 26, while those preferring Friday total 13. 5 Members voted for both/either. So far then, the monthly meetings will continue to take place on Tuesday nights.
So far a total of 44 responses have been received, from a possible total of 84 members. Just over 50% - good but not brilliant! If you still have a copy of the questionnaire unsent, please return it to John Gilmour ASAP!
Bill’s Binocular Targets – March
Bill Leslie (described somewhere in this newsletter as ‘inimitable’) hosted a new feature at this meeting. For a while now he has prepared finder charts and information sheets for his favourite binocular objects and presented them at SIGMA meetings. He thought that as all the preparatory work was already done, we might also benefit from them.
Bill explained that he was surprised and impressed by how many people actually own binoculars and use them for astronomy. They are ideal for the purpose, requiring no expensive or complicated mounting hardware or esoteric care routines, and give a nice wide field of view. With their wide field they can offer the very best views available of some large objects, such as open clusters and large bright nebulae.
Before describing his list of targets for March, Bill explained how to use our hands to measure apparent distances in the sky. The directions on his information sheet use numbers of degrees, and so it is essential to be able to measure those distances easily. By holding out a hand at arm’s length and holding three fingers together, they cover about 5 degrees. The width of the full fist is about 10 degrees. By extending the pinkie and index finger you can cover about 15 degrees, and from tip of thumb to tip of pinkie is about 20-25 degrees. This is a very ‘handy’ way to determine distances between sky objects…
Bill’s information sheet has been uploaded onto the Society’s website, and can be found here. This month’s objects include M44, open cluster in Cancer; M46 and M47, open clusters in Monoceros; Melotte 3, open cluster in Coma Berenices; and M3, globular cluster in Canes Venatici. All of these targets are easy to find and impressive to behold through standard 10x50 binoculars, so give them a go if you get a chance!
Bill promised to return with more Binocular Targets in the autumn.
The Main Event
‘Meteors’ by Neil Bone
Neil is originally from Campbeltown in Kintyre, and is a biologist by profession. His current work commitments have relocated him to Chichester, where he works at the University of Sussex. He has been pursuing astronomy since about age 7, before the days of the Apollo spacecraft! He has been Director of the BAA Meteor Section since 1992, and was formerly (1981-89) Director of the JAS/SPA Aurora Section - a post now held by Ian Brantingham of SIGMA. Neil spends a lot of time writing too, and has been contributing to Astronomy Now magazine since issue 2, back in 1987, and has six books to his name, including ‘Aurora: Observing and Recording Nature's Light Show' - the last of these published by Springer in 2007.
Neil started off by showing a picture from 1783 that showed a group of meteors crossing the sky above a group of observers below. He was quick to point out that they were ‘meteors’, not ‘meteorites’, as to be a meteorite the meteor must actually hit the Earth. At that time it was not known for sure that meteors came from outside the Earth’s atmosphere. Some people thought that out-gassing from the Earth itself caused them. It was only later that the link between comets and meteor showers was discovered.
As comets approach the Sun, their outer surface starts to break down and crumble away. We see the results as magnificent dust tails, like those that accompanied comets such as Hale-Bopp or Hyakutake. The particles that make up those tails do not simply disappear, but spread out around the solar system in orbiting rings. Even after the ‘parent’ comet has passed far away out of the solar system, that debris is still present, and it often happens that the Earth’s orbit and the orbit of a ring of dust and debris might coincide at regular intervals. When the Earth passes through one of these rings of dusty material, those particles come into contact with the Earth’s atmosphere and burn up, often ionising the atmosphere and leaving bright trails behind them as they do so.
That is the classic shooting star, or meteor, and different meteor showers are associated with different comets. For example, the Perseid shower is associated with comet Swift Tuttle. The particles are often only the same sort of density as cigarette ash, sand or similar, so are incredibly small. However, when travelling at speeds of up to 42 miles/sec you don’t need to be physically big to make a big impression on the atmosphere that you are colliding with!
Larger particles can last longer in the atmosphere before burning up completely, and can break up into several smaller pieces. Others can end up as ‘fireballs’ or bolides that look for all the world like nature’s very own fireworks and can be incredibly bright – up to magnitude –8, or as bright as the crescent Moon!
The regularity with which the Earth passes through some of these rings of comet-dust means that meteor showers are often easy to predict, and often occur at the same time each year, although the peak periods can vary slightly. Meteors that are part of a meteor shower will appear to come from one particular point in the sky, although they will travel in all directions (as perceived by the observer’s eye) from that point. This was ascertained through observations made from the 1920’s to 1950’s, and the apparent point of origin is known as the radiant. When setting out to observe a shower, it is essential to be comfortable and warmly dressed, even for the summer showers, as temperatures can drop sharply and sitting around isn’t the most invigorating form of activity on a chilly night. A deckchair is recommended (preferably padded for comfort) and multiple layers of clothing. A clipboard, several pencils/pens, and a red torch with spare batteries handy would also be good additions to the meteor-observer’s equipment locker. Observing sheets can be obtained directly from the BAA Meteor Section, and are fairly self-explanatory.
Neil explained that when recording meteors himself, he notes them down on scrap paper and then transfers the data to an official form later when he has more time to do so accurately, rather than potentially missing meteors while recording information. He recommended looking slightly to one side of the radiant too, as meteors that come directly from the radiant will be travelling straight towards the eye, and so will appear foreshortened, and only last a very short time. This reduces the chance of spotting it. Those off to the side will be travelling longer across the sky and so are more likely to be picked up by the eye, especially the rod photoreceptors which allow our peripheral vision to be so good at night.
So, very little equipment is needed; only clear nights and some patience. Neil also recommended pacing oneself somewhat, perhaps taking a break every hour and moving around to get the circulation going again; drinking and/eating, and then going back to the watch refreshed again. As he said, meteor-watches are not a competition. It doesn’t matter how many you see, it matters more that you record what you do see accurately and can submit your reports to the BAA with as much information about the observing conditions, time, location etc that you can.
Meteors can be caught photographically as well, by leaving the camera shutter open for a long period of time. Whether driven or undriven, the meteors will show up as streaks or lines against the background image. Sometimes, the effect can be very dramatic, especially if the photographer is lucky enough to capture a particularly bright meteor. Meteor photography is one area where film is still better than digital. Opening the shutter for very long periods on a digital camera will result in a very large file to dump onto the memory card, meaning a long time to transfer, meaning a high probability of missing more meteors while the camera does all that.
Neil proved how effective photography is in meteor observing by showing many beautiful images with numerous meteor-trails on them. One particularly outstanding photo was of a Kappa Cygnid meteor taken in 2007. Many other examples were shown, and Neil recommended the use of relatively simple equipment to capture similar images: 28mm wide-angle lens, 400 – 800 ASA film, and a shutter release cable.
Neil’s talk was very comprehensive, and covered such other topics as spectroscopy, ‘fireball patrol’ photography, and how the information submitted in meteor-watch reports is interpreted and applied to determining such things as the Zenithal Hourly Rate (ZHR) of individual meteor showers. This can then show how the orbits of the dust and the Earth are changing relative to each other, and predictions can be made for particularly outstanding shows of meteors, such as the fantastic peak of the Leonid storm in December 2001.
One forecast Neil did make before closing, was that the last ever really outstanding peak of the Leonids may well occur in 2103, and that event might well be worth hanging around for! Given the quality of Neil’s talk, and the inspiration he infused us with, he can be sure that we will try!
Highland Skies – March 2008
March could be thought of as the beginning of the end of the observing season. On Sunday 30th the clocks will ‘spring forward’ by one hour, meaning it will get dark one hour later than it does on the 29th. That will make a real difference to observing opportunities as it will not get really dark until 9pm or thereabouts, and as we speed into April it will get later and later.
So we have a lot to see during March and we’d better make the most of the time we have to see it! The galaxy fields of Leo and Virgo are high enough when darkness falls to allow us to see some fine groupings of galaxies in medium aperture telescopes. The easiest would be the Leo Triplet group of galaxies, comprising M65, M66 and NGC 3628.
As expected by their membership of the Messier list of objects, M65 and M66 are the easiest to see of the triplet, as they are magnitude 10.3 and 9.7 respectively. Even a small 80mm refractor should show them comfortably. NGC 3628 is a bit dimmer at magnitude 14. When I looked that up, it surprised me, as I’d always been able to see it relatively easily in my 8-inch Dobsonian, whereas a magnitude 14 object should really be pushing the limits of such a ‘scope.
Maybe my skies are better than I think, or perhaps it’s to do with how my eyes work. When framing both M65 and M66 in a wide-angle eyepiece, with one at each extreme edge of the field of view, NGC 3628 will be towards the edge of the field furthest away from the others. Now, while concentrating my direct vision on M65 or M66 (using the cone photoreceptors in my eye), the photoreceptors known as rods which are most sensitive at night once dark-adapted will pick up the faint smudge that is NGC 3628! Because the rods do not operate in the centre of the field of vision, faint objects can be best observed by aiming your direct vision away from them and allowing the super-sensitive rods to pick them up with ‘averted vision’. This is a popular technique for picking up faint galaxies and nebulae and gradually building detailed observations of them.
Another group of three galaxies lies beneath the mid-section of the Lion’s belly. M95, M96 and M105 all shine at 9th magnitude, and are also easily detectable in small ‘scopes. M95 is a barred spiral galaxy, and with reasonable aperture and good conditions you should be able to detect the bar running across the centre of the galaxy. It is face on to us, so is quite striking in appearance. M96 is very similar but slightly brighter and has no bar. By contrast, M105 is an elliptical galaxy, so has no spiral structure visible to us at the eyepiece, but is still an interesting object to observe. You can increase the magnification, building it up in steps, and see how it gets larger in the eyepiece, until you reach a point where increasing the magnification yields no improvement in the view.
Close by are other, fainter galaxies. Of particular note are NGC 3384 (lenticular) and NGC 3389 (spiral), which you may notice off to the side while observing M105 with a medium aperture ‘scope and wide-ish field eyepiece.
Apparently very close to this grouping at the moment is the planet Saturn, with its rings almost edge-on to us. It will be interesting to start off a night by observing these fascinating and diverse galaxies, all millions of light years distant, and then finish off by zooming in to one of our ‘closer’ celestial neighbours, Saturn, which lies only 771 million miles or so away!
Dark skies and good hunting!
Next Time. The next meeting will take place back at the Green House on Tuesday 1st April, and will be the Society’s AGM for 2008. It will start at 7.30pm and there are bound to be a lot of important updates and discussions taking place. After the business part has been completed, a DVD will be shown. Not sure what it is yet, but I think it’s more likely to be Patrick Moore than Barbarella. Still, there will also be the usual refreshment break, and plenty of time for catching up with the latest news about astronomy and space.
Until April 1st, Dark Skies!
* Not actually guaranteed.
** Moon-burn is not a real condition.