WADHURST ASTRONOMICAL SOCIETY

FEBRUARY NEWSLETTER 2005

INDEX: MEETINGS, OTHER NEWS, CONTACTS

MEETINGS

JANUARY COMMITTEE MEETING

      The Wadhurst Astronomical Society's new committee had their first meeting in Frant on Monday 10th January  2005.  The members attending were:

Tim Bance               Chairman

Ian Reeves              Secretary

Treasurer               Jason Gardner

Michael Harte           Publicity and Web-site

Geoff Rathbone          Newsletter Editor

Joan Grace

Mike Wyles

With apologies from Ian King and John Vale-Taylor.

      Tim took the Chair and then Ian Reeves, the retiring Treasurer stated the accounts were in a healthy state as he handed over to Jason Gardner our new Treasurer.

      The shape of the Society was discussed and It was felt that more accent should be devoted to practical observing and observing evenings should be considered.

      The Chairman made an interesting suggestion that we might approach either Greenwich or Herstmonceux Observatories to try and organise a Society evening.  Members would be expected to make their own travel arrangements if a visit could be arranged.

      Monthly sky notes had been enjoyed by members in the past and should be reintroduced.

      The next Committee meeting is to take place at the Abergavenny Arms, Frant, on Monday 11th April 2005 at 8.00 pm.

JANUARY  MEETING

The Sun

Talk given by Peter Gill on Wednesday 19th January 2005

Peter Gill is a member of the Astronomical Society in Eastbourne where he lives, and we are grateful to Ian Reeves who brought him to the meeting and to Larry Mowat who kindly took him back.  Peter doesn't drive and he wanted to show two 16 mm film clips and couldn't have brought his projector on the train.

Peter began by bringing apologies from Norman Walker, an honorary member of Eastbourne Astronomical Society, who should have been speaking to us at the December meeting, but missed the date owing to a wall chart malfunction...

Several slides introduced us to the Sun beginning with the core composed of Hydrogen and helium at enormous pressure.  The core's mass is 60% of the Sun's total mass with a temperature of 15 million degrees Kelvin.  The nuclear reaction inside the Sun takes place outside the core in an area called the Radiative zone.  The high-energy radiation then gradually diffuses outwards to an area called the Convection Zone just beneath the surface.  A photon takes approximately 2 million years on average after being created in the Radiative Zone to find its way to the surface before being radiated out into space.

We were shown a slide of the Sun indicating that it is like a huge gong, with the surface oscillating with a period of five minutes with many harmonics.  Observing these oscillations have helped solar astronomers to predict the mechanics of the Sun's interior.

Peter then came to Sun's surface with its sunspots.  He said that writings from China and Korea dating back thousands of years showed that observers had been aware of large sunspots just by eye, although they firmly believed that these spots were objects passing in front of the Sun. It was stressed at this point very strongly that one should never look at the sun without proper protection such as Mylar filter, a Herschel wedge or by viewing the projected image on a suitable screen.

We were shown a very early photograph of a sunspot taken in 1870 by L. M. Ruggerford, which filled the screen and was so clear we could see remarkable detail both at the edge of a large spot and the surrounding area.

On the 20th of January 1926 a photograph was taken of a huge bipolar group of sunspots, and it was recorded that 3 days later an enormous solar flare was observed.  Again in 1951 a detailed photograph of a sunspot taken at Mount Wilson and covering an area of 4,865 square kilometres showed how gas flows out and then is convected back in again directed by very strong magnetic fields.

The surface of the sun, the photosphere, is made up of granules that exist for only about 8 minutes each.  These are about 1,000 km across, and are separated by a dark area where cooler material is falling back into the surface of the sun.

Peter explained that early solar astronomers determined by sunspot observations that the Sun rotates fastest at the equator and slower the higher the latitude. 

There is an eleven-year cycle of sunspot activity.  We were shown the butterfly diagram of sunspot appearance where the first spots after a quiet period occur in the upper latitudes in both hemispheres.  As the cycle progresses, they appear in latitudes closer to the equator.  Despite the eleven-year cycle, there was a period between 1650 and 1700 called the Maunder Minimum when there were virtually no sunspots.  At this time it was also noted that the earth as a whole cooled.

Peter Gill then told us about the first discovery of prominences during solar eclipses, although at the time astronomers didn't know whether they were on the moon or actually on the Sun.  Solar astronomers later used an occulting disk to blank out the photosphere and were then able to observe the prominences at the edge of the disk, thus confirming that they were part of the Sun.  Peter then showed several slides of the Sun's surface taken in hydrogen-alpha light and calcium light and indicated the existence of flares adjacent to sunspots throwing off material into space.

We then came to some quite remarkable 16 mm film made in 1940s with an excellent sound track shown on Peter's projector with prominences speeded up 720 times to show their movement.  These reached 30,000 miles in height and travelled at 20 miles per second.  Now it was possible to see how the prominences actually formed from a condensation area above sunspots.  This area, sometimes difficult to see, suddenly develops into an arch beneath it from where material falls into the sunspots and not as it often appears, as though they start from the spots.

Other flares ejected material into space, falling back again unless the material reached escape velocity and was expelled out into space.

A second film made in early 1960s showed more of the photosphere and some amazing pictures of eruptions in the area of a sunspot with a resulting huge ripple flowing outwards across the surface of the sun rather like a stone thrown into a pond.

      Finally Peter projected some slides of his early drawings of sunspots showing great detail, together with handwritten observation data.  He had devised a projection grid onto which he could track sunspots projected through his telescope.  From this he had been able to see the variable rotation of the Sun's latitudes.

      It was an excellent talk and we felt privileged to have seen the rare 16 mm films.

NEXT MEETINGS  

      The next meeting of the Society is on Wednesday 16th of February 2005 beginning at 7.30 pm and is called "Telescope Viewing from Uplands" and starting from the Drama Studio.

      It is an open evening when observing techniques and problems can be discussed.  It is hope to be a practical evening with the chance to observe from the grounds of the college providing the night sky is clear.

      Members are invited to bring along their telescopes and other astronomical equipment together with any photographs they think others would find interesting.

Early information of the meetings in March and April:

      Wednesday 16th March the speaker will be Greg Smye-Rumsby, whose talk is called "The Craig Telescope at Wandsworth".

      Wednesday 20th April the talk given by John Murrel is called "Virtual Observatories - Fireside Astronomy".

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OTHER NEWS

SUBSCRIPTION RENEWAL REMINDER

Member's subscriptions for the current season were due from the beginning of November 2004.

      Subs for the current session 2004/2005 are now due:

      Single membership       15

      Joint membership         20

      Our new Treasurer would be delighted to receive a cheque made payable to W.A.S. and addressed to him, Jason Gardner at: 67 Woodside Road, Rusthall, Tunbridge Wells, Kent  TN14 8PY, or cheque/cash at the next meeting.

OTHER NOTES

February Night Sky

We can still enjoy Winter's more brilliant constellations.  Orion still dominates the south-western sky with its bright Belt and hanging Sword.  The Sword and Belt are surrounded by three brilliant stars, Betelgeuse, Bellatrix and Rigel.  Draw a line south-eastward through the three stars of the Belt to see Sirius, the brightest star.  Sirius is known as the Dog Star because it lies in the constellation of Canis Major, the larger of Orion's two dogs.

Even in light polluted skies, one can see the almost equilateral Winter Triangle formed by Sirius, Betelgeuse and Procyon, which is in Canis Minor.

Two beautiful star clusters can be found in Gemini, near its border with Taurus, and both with the background of the Milky Way.  The pair make a remarkable contrast.  M35 is filled with blue-white stars that flash like diamonds.  The other star cluster, NGC 2158, is much fainter and with yellow and red stars.  One explanation for the difference is that the latter cluster is six times further away.

Of local events, Comet Machholz may well be visible to the naked eye.  It is swiftly moving north through Cassiopeia into Cepheus.  The moonless beginning of the month offers the best time to see it.  I have seen it through binoculars and then once having determined where it is can just make it out with the naked eye. Website www.heavens-above.com gives daily updates of its position.

Saturn is visible all night in Gemini.  We are learning more about this huge planet and its moons from the Cassini-Huygens mission, which is returning splendid photographs.  Five of its moons should be visible around it; while Titan, its biggest, is further away but should be identifiable.  Saturn's rings are as wide open as we will ever see them.  Jupiter rises before midnight in Virgo.  Three of its four giant moons are close to it, while the fourth, Io, is lost in the vastness of Jupiter.  The other planets are not easily visible.

Adrian Berry writes in the Telegraph about the tortured galaxy Markarian 766, some 170 million light years away in the constellation of Coma Berenice.

Observed by Europe's XMM Newton X-ray satellite, a new illustration of how matter behaves in the vicinity of giant black holes with a clarity never revealed before.

Using the same technique as the radar guns used by the police to trap speeding motorists, the satellites detectors calculated how fast matter surrounding the black hole was travelling.  It was racing round the hole at about 20,000 miles per second.

Since nearly all galaxies in the universe have black holes in the centres, we can deduce from this observation that they are surrounded by furiously spinning, nearly circular bands of matter.  Seemingly empty Coma Berenice swarms with galaxies.  The brightest is the Black Eye Galaxy (M64), 12 million light-years away, which in appearance more resembles an open, hungry mouth.

Another, one of the most famous galaxies in the sky is NGC 4565, a classic "edge on" spiral galaxy. 

Welcome to a new member

      We would like to welcome a new member to the Society.  He is Colin Hobday who lives in Ticehurst and we hope he finds plenty of interest within the society.

Murray Barber

      Society member and former Chairman, Murray Barber has now moved to Kimworthy in Devon where he and Valerie, his wife are setting out on a new adventure by offering astronomically related holidays in a part of the country with the darkest skies they could find after a good deal of research.

      They have taken over a site which already has two chalets, and Murray with his colleague Tony Gibbons are in the process of building and equiping the first of their proposed on-site observatories.

      They have a new web site which can be found at: www.astroadventures.co.uk

      For the time being, Valerie is staying behind at Sevenoaks so that Helen, their daughter can complete her A-levels, and hopes to attend the Society meetings in the meantime.

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CONTACTS

Chairman          Tim Bance                         01732  832745                   timbance@hotmail.com

Secretary         Ian Reeves                        01892  784255

Treasurer         Jason Gardner                       01892 528799

Publicity  & Web site       Michael Harte         01892 783292             michael@greenman.demon.co.uk

Editor            Geoff Rathbone                        01959  524727            Geoff@rathbone007.fsnet.co.uk

Any material for inclusion in the February Newsletter should be with the Editor by February 28th  2005

 

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