Talk on the Moon

Given by Peter Gill on 21st April 2004

In Peter Gill's introduction, Murray Barber mentioned an astronomer in America who has suggested nuking the moon to improve the night sky!  Peter said that by the end of the evening he hoped to have changed member's opinions about this.

He began his talk by saying that because of their relative sizes compared with the other planets the earth-moon system is often regarded as a double planet.  Until 1608 and the invention of the telescope not a great deal of detail was know about the moon.  The same face is always towards the earth-bound observer, but it was not until the observer was able to take a magnified look that it was found the not just 50% of the surface was visible, but due to various orbital variances and librations, as much as 59% can be observed.

The first detailed map of the moon with lunar nomenclature was published by Hevelius in 1647 and Peter showed a number of detailed drawings from Hevelius' publication.  One of the drawings was of crater Wilhelm Humboldt which he then compared with a modern observatory photograph and then with a picture taken from a Lunar Lander.  This confirmed the accuracy of Hevelius' drawing and confirmed the crests and dips.

Maury is a double crater with a basaltic floor, and in the slide we could see radial cracks that had shrunk, and a line of small craters possibly caused by a meteor that had split into a trail before impact.

Apollo 8 was the first American manned mission to swing round behind the moon; although Apollo 8 was the first craft to go into orbit, taking many images of the far side of the moon's surface. 

Several controlled unmanned lunar landings had taken place to ensure the surface would support a manned landing.  Then we were shown the famous photograph of Buz Aldrin standing on the surface of the moon after the soft landing during the Apollo 11 mission.

Whilst on the lunar surface a number of instruments were installed and these have continued to give information about the solar wind, micro-meteorites and lunar quakes.

Pictures from Apollo 17 show a stark landscape, but one piece of evidence for using manned missions was demonstrated when orange soil was noticed by one of the astronauts and samples were taken to be returned to earth.  This was discovered to have been ejected from a nearby impact and consisted of minute glass beads.

Peter showed slides of other samples returned for analysis such as a pumice-like rock containing glass bubbles. A photomicrograph showed that the rock had been broken up and reformed many times.  It was also determined that in the craters, the higher rocks were in fact turned over from the bedrock.

It is now thought that the core of the moon is molten with a crust 65 Km thick.  This has mainly been determined through examining the effects of moonquakes.

Peter continued his talk with a theoretical history of the moon, formed through evidence accumulated by the US Geological Survey.  Theory suggests that a meteor the size of Mercury was involved in a glancing impact with the primordial earth, knocking out the material that was to form the moon.

Then much more recently, 3.8 million years ago, Copernicus was formed after a huge impact.  Prior to this, it is thought that there were no Mares (seas) on the moon's surface.  After about 3,500 years after impact, new features only just began to appear.  3.3 million years ago the Apennines began to appear, but Copernicus would still not have been visible, in fact theory suggests that the crater only began to appear after 2.5 million years after the impact.

In the second part of Peter's talk, we were introduced to 85 Km diameter Tycho, one of the most prominent craters on the moon with its ray structure dominating the surface near full moon.  It was explained that the dark ring around the rim of the crater exists because very little debris from impact would have gone straight up and then fallen straight back down.  At lunar dawn and evening, Tycho is hardly visible because there are very few shadows.

We spent most of the rest of the evening, looking at various craters carefully drawn by observers viewing through the eye-piece of the telescope and talked of the difficulty of being accurate.  Peter talked of various techniques, such as the German method of drawing rills using short lines to illustrate their sides, and problems when astronomers have tried to show ridges or troughs.  He showed this by comparing many old drawings with the same features taken recently from space.

Finally, Peter showed a number of slides of interesting features on the moon's surface such as Wargentin in the Schikard group with its famous plateau thought now to be a crater filled during volcanic activity.

By the end of the evening, most members' interests had certainly been renewed in observing the moon, rather than cursing it because of its effect on the night sky.


Subsequently, Peter Gill has written to Murray with this additional note:

"Something I forgot to do was give the meeting particulars of the 'special' Eastbourne Astronomical Society meeting on Saturday 5 June (three days before the transit of Venus) at 19.30, when we have Dr Brian Marsden of the Smithsonian Center for Astrophysics (Cambridge, Mass.) speaking to us on 'Trans-Neptunian Objects' and 'The IAU Central Bureau for Astronomical Telegrams and Its Work'.

"You and any of your colleagues would be welcome to come along (no charge!). Our meetings are held in Willingdon Memorial Hall, Church Street, Willingdon, on the south-western corner of the cross-roads between the A2270 and Church Street (which extends across both sides of the A2270), immediately north of the Eastbourne boundary. See map

The hall is on the WESTERN side of Church Street (not named on the map); it is not the church hall on the opposite side of the road. Please note that as there is only a small car park, which is reserved for the speaker, etc., it is requested that members and visitors park on the road, which can get fairly congested with parked cars. So I'd suggest that anyone coming along tries to get to the hall in good time. Doors open at 19.00.

All very best wishes, Peter"  


      The next Wadhurst Astronomical Society meeting will be held on Wednesday, May 19th 2004 when the talk will be given by Mike Maunder and will be called "The Transit of Venus/Astrophotography".

      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.





           There will be Observing Session on the following Friday:  21st May

      The sessions meet at 7.30 pm in the Crow and Gate pub, about a mile south of Crowborough on the A26 main Uckfield road.  Then at 8.00 pm the group move onto Ashdown Forest with Seanís and the Societyís telescopes and possibly others.

      Sean Tampsett suggests that interested members phone him between 6.00 pm and 7.00 pm to make sure the session is going ahead.  



Steve Camp and Doug Biswell have kindly taken on the position of society secretaries.  I would like to thank them and to ask the membership to support them in this new responsibility.  If anyone in the WAS has a particular topic that they would like to see discussed by a guest speaker, do please pass your comments on to Steve and Doug for consideration.

I have for many years been the Chair of the WAS and have very much enjoyed my tenure and also the good humour, advice and support from an excellent committee and membership.  The time has come for myself to stand down.   Some of you will know of my other interests and projects which I need to apply myself to in a more committed way.  In any event a change is good!  A new Chair will bring renewed enthusiasm and will I'm sure steer the WAS onwards and upwards.  It has been said that the Chair of any society should have an encyclopaedic knowledge but the truth is that enthusiasm, communication and commitment are the most important credentials.  I will in my present capacity officially chair the last meeting this July.   Do please contact myself or any other committee member if you wish to be Chair.  I would be happy to discuss and advise any potential candidate for this new opening within the Society. 

  Murray R. Barber



      We have just received the annual booking renewal papers from Uplands College for the period April 2004 - March 2005.  The news is that the cost of hiring the drama studio is to rise from £312 to £318 for the 11 months commencing April 2004 until March 2005.

      Members may not be aware that it costs us approximately £50 to conduct each monthly meeting.  The hire of the room is the major part and we are very thankful that most speakers have adopted a generous "reimbursement of travel expenses only fee" or no fee at all.  Until last year our not insubstantial catering costs were absorbed by one or two benefactors. 

It is not the Committee's present intention to increase subscriptions although we would appreciate it if the gang of four would pay up. The ideal way to keep costs and income in balance is for members to introduce some fresh members to join the Society.

      The Committee is not an exclusive elite.  Members may well have looked at its composition and have adopted the view that "if it ain't broke don't change it".  However, only one member (last year) has joined the Committee in the past 4 years.  Some have served for over 6 years and that is too long.  We are concerned that if volunteers are not prepared to join us, this could lead along the path followed by at least two earlier similar societies in this area - extinction.

      There is no need to be apprehensive; at least two members of the present committee have a meagre knowledge of astronomy and the others would agree that there is more wisdom on the subject outside the committee than in it.  You don't need a late pass to attend four one-hour meetings a year.

Ian Reeves



Chairman:      Murray R. Barber               01892 654618


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



Copy for the July Newsletter should be with the Editor by June 30th  2004