Recent innovations in mobile planetariums

  Talk given on Wednesday 21st July 2004 by Murray Barber using his mobile planetarium

Most members of the Society know that Murray Barber and Valerie his wife give many talks to Schools and other organisations and have done so for many years.  He owns his own sixteen-foot high inflatable planetarium, which only just fitted into the Drama Studio at Uplands College.  The Dome had already been prepared before we arrived and Murray welcomed members and gave a brief introduction into how the mobile planetarium came into being.

About twenty years ago Phil Sadler in Massachusetts, USA, took his son to see a lecture in a local Planetarium Theatre.  When they got home his son asked if it was possible to recreate the theatre.  Phil thought about this and actually constructed his own planetarium, which after a lot of improvementsbecame a workable dome and projector.  The problem making a practicable projector was overcome by using black film in the form of a topped cylinder.  He then created the stars on the surface of the film.  He used a very tiny bulb with a filament only 2 mm in length to obtain the definition.  To project the stars in their relative correct positions on the inside of the dome was quite an achievement and he used a computer to position the night-sky on the drum.  Projection through a sphere would have been far easier but less practical.

Murray also pointed out that on the original drum, there was no Milky Way.

We were then invited into the dome and all managed to sit quite comfortably round the perimeter in one group.  This part of the evening was divided into two with a coffee break in between.

Murray described the cylinder and how the planets were projected through separate lenses enabling their positions in the night sky to be very precise.  The positions of the sun and moon were limited to twelve locations simply because of room within the pattern of stars on the cylinder's surface.  One surprising fact was that it was almost impossible to detect the junction of the side of the cylinder and the "lid" in the spread of projected stars.

With atmospheric background music the lights dimmed and we were presented with the cloudless night sky as it would be that night.  Although very clear, some of the brighter objects close to the horizon tended to be a little distorted.  Murray took us on an enthusiastic time travel through the following twenty-four hours, describing some of the star patterns such as the Summer Triangle formed by Deneb,Vega and Altair, and the square of Pegasus using the stars as a guide to other interesting objects.

During our coffee break the Projector was changed to the new FibreArc light source projector and at the start of this part of the evening, the clarity and sharpness of the night sky was very impressive, and with the new Multilens drum we were able to see the Milky Way in its entirety as seen from the earth.  The artwork for this had been suggested and produced by Murray himself and is now used by the manufacturers.

Murray then asked if any member had any objects they would like to have pointed out, and with his usual thoroughness not only did he indicate the objects but also gave guidelines as to how to find them, such as M1 the Crab Nebula.

Finally we were shown a separate drum that gave the relative sizes of the sun and planets and a surprising amount of statistics and detail.  Using this drum Murray and Valerie were able to blank out irrelevant parts depending on the age level of the audience they were talking to.

It was a very interesting evening and it was particularly revealing to compare the old projection method with the new.



The next meeting of the Wadhurst Astronomical Society will be on Wednesday 15th September when the speaker will be Jerry Workman, who has spoken to us before in January 2002 when his subject on that occasion was "Mars Revisited".

As usual, the meeting will be held in the Drama Studio at Uplands College.  The doors open at 7.15 and the meeting starts at 7.30 prompt.




The Federation of Astronomical Societies (FAS) is to hold a convention on 2nd October 2004 at the Institute of Astronomy, Madingley Road, Cambridge.

The doors open at 8.30 am and there will be various trade stands and society displays.

Confirmed speakers include Professor Douglas Gough, Dr. Paul Murdin, Guy Hurst and Dr. Cathie Clark.

On the day, tickets will cost 8, but advanced tickets may be obtained at 7 and are available from Stan Waterman, "Amadeus House" Temple End, Charlton, Hitchin, Herts.  SG4  7TE.  Telephone: 01462  433912.

email: ticket.sales@fedastro.org.uk

Further information can be obtained from the internet at http://www.fedastro.org.uk/


Our financial year closes on the 31st October 2004.  Shortly after that all members of the Society have to elect a committee for the next year.  Half of the present team will be standing down while the other half is looking forward to welcoming 3 or 4 others from the 41 members yet to take their turn, for up to a couple of years on the committee.  Under paragraph 5 of our Constitution "Any member shall be able to nominate other members for election subject to the nomination being seconded."  Please send your nominations in to one of the Secretaries, Doug Biswell or Steve Camp.  If you are not on the net then send them to Ian Reeves.  Do so now, so that election preparations can be made well ahead of the annual meeting.  Our contact numbers are at the foot of this Newsletter.  If you cannot remember someone's full name describe him or her to the Treasurer and he will endeavour to help.  His address is: Ian Reeves, WAS Treasurer, Broadwater Lodge, Stone Cross Road, Wadhurst, East Sussex.  TN5 6LR.

It is emphasised that candidates for committee membership do not have to be astro experts.  Remember, we invite experts along to give the talks and there is a wealth of knowledge within the now large membership including Murray, Joan, Ian King and others to call upon.

The Society is in funds.  It has not had to touch reserves this year and might do better than break even by the end of our year.  More good news, the committee does not see any reason at the moment for increasing subscription rates.



Chairman:      Vacant Position

Secretaries:  Steve Camp       steve.camp52@btopenworld.com

                  Doug Biswell           dougrbiswell@aol.com

Treasurer:      Ian Reeves                        01892 784255

Membership Sec:   Joan Grace             01892 783721

Editor:           Geoff Rathbone                01959 524727


Publicity & Web Site:      Michael Harte       01892 783292


Dir. of  Obs:  Sean Tampsett                01892 667092


Any material for inclusion in the October Newsletter should be with the Editor by September 30th  2004