Calendar of Meetings 2025-2026

We usually meet at St Lawrence Church, Slough

Members will be informed by email of the location of meetings.
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Meetings with external speakers are held at St Lawrence Church, Upton Ct Rd, Slough SL3 7LS
7.30 pm, 2nd Friday of each month (check the diary)

We are now holding less classroom type meetings, instead concentrating on shorter prepared presentations, and planning observing whenever it is clear on those nights

Please check your email as we will advise members of upcoming events through this medium.

Visits and Public Viewing Evenings

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Meetings are open for anyone to attend but if you are not a member we would ask for a contribution of £3 towards the costs involved in running the meeting.

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Sir William Herschel (1738-1822) - Tony Fanning - 8 February 2002

William Herschel, who became one of the most acute astronomical observers of all time, was born in Hanover, where his father was a bandmaster in the Hanoverian Guard. Young William joined the band at the age of fourteen, playing the flute and the violin. After a brief spell in England in 1756, when there was talk of an invasion by Napoleon, the guards returned to Hanover, only to be routed at the Battle of Hastenbeck. This marked the end of his brief military career. He and his brother escaped to England and when peace was declared in 1759, William decided to make it his home. Recognising that the Home Counties were 'over-stocked with musicians', he headed north and for the next seven years made a very reasonable though often rather peripatetic living giving lessons, directing concerts, and so on. All his life he had a voracious appetite for knowledge and so, planning to write a treatise on music, he began to study harmony and mathematics, a significant step in view of what was to follow. After spells in Leeds and Halifax, where he famously won a competition for the post of organist, he finally settled in fashionable Bath, as organist in the Octagon Chapel. Here he was joined by his brother Alexander and later by his sister Caroline, both of whom shared the family's musical talents. William quickly became very popular, playing in the Pump Room Orchestra and giving lessons in the Violin, Oboe, Organ, Harpsichord and the Guitar. In 1777 he was appointed to the top post as Director of Concerts in Bath, offering him every prospect of a brilliant musical career, had it not been for the fact that by then he had become passionately hooked on astronomy.

Herschel's imagination was fired by reading 'Ferguson's Astronomy', a graphic account of the wonders of the heavens, and he was determined to see things with his own eyes. After hiring a small refractor, which soon proved inadequate, he turned his attention to reflectors, and set about learning to cast and polish mirrors which, at that time, had to be made from speculum metal, an alloy of copper and tin. After many failures, in 1774 he produced one with what he described as 'a tolerable figure', a mirror 5-inches in diameter, with a focal length of 5-feet, and, turning it on to the Great Nebula in Orion, he was captured for life. Larger telescopes followed and, on 13 March 1781, while studying the stars in the constellation of Gemini, during the second of his systematic surveys of the heavens, he came across an object which appeared quite unlike a star. It showed a disc and, when he increased the magnification, the object increased in size - which stars do not do! Four nights later the object had moved considerably amongst the stars and it had therefore to be within the Solar system. Herschel believed it to be a comet - and his life was changed for ever.

Many things started to happen. The sighting was reported to the Royal Society by his friend, Dr Watson; astronomers, both in England and on the continent, confirmed the sighting; the Astronomer Royal suggested that the new object might be a new Planet, the first to be discovered since the dawn of history; a Finnish Astronomer, Anders Lexel, calculated its orbit, giving it a period of some 83 years, and so placing it twice as far from the Sun as Saturn; Herschel was elected a Fellow of the Royal Society and awarded its Copley Medal, and finally, after he had been summoned to Windsor Castle to show the Royal family some of the sights with his telescope, King George III offered him a post as King's Astronomer, with a pension of £200 a year, provided he came to live near Windsor and was available to entertain the Royal family when called upon. This sum was about half what he had been earning in Bath - his friend, Dr Watson exclaimed 'Never bought Monarch honour so cheap' - but it did enable him to abandon music and to devote his life to astronomy.

The family moved to an old hunting lodge in Datchet (described by Caroline as a 'dilapidated ruin') and it was here, in 1783, that William built his 'Large 20-foot', with a 19-inch mirror, which was to become his favourite and most productive telescope. A small 20-foot with a 12-inch mirror had already been completed in Bath. Herschel settled down to his systematic sweeping of the heavens, noting all unusual objects for the first of the many catalogues of his work that were to appear over the next 40 years. Caroline was appointed The Astronomical Assistant, available for recording observations, helping to set up or move the telescopes, and so on. She was also given a small 'sweeper' so that she. too could look for unusual objects when not required for other duties. Later on she was able to undertake the calculations necessary to convert the observed altitude and azimuth of objects into Right Ascension and Declination. (or Polar Distance, as was usually used at that time.) She was later to achieve fame as the discoverer of eight new comets. A few years earlier the French Astronomer Messier had published his famous catalogue of a hundred nebulous objects. By the end of his life Herschel had discovered some 2900, several of which he credited to Caroline.

Naming the new planet took a long time. William himself wanted to call it Georgium Sidus, in honour of his royal patron, but eventually the name Uranus (in mythology, the father of Saturn) was suggested by Bode. This was quickly adopted on the continent, but in England, for a long while, it was still referred to as the Georgian planet.

Herschel's energy was prodigious. On a clear night he might well remain at the telescope for fourteen hours, with the temperature well below zero. However after three years the dampness and cold took their toll and he became very ill It was clear they would have to move. Clayhall Farm House in Old Windsor appeared to be an ideal, solution, being closer to the Castle and on the edge of the Great Park. By this time Herschel was already making plans for a very much larger telescope, in the hope that he could resolve many of the nebulous patches he could see into discrete stars. However it quickly became clear that their landlady, who Caroline described as a 'litigious woman', intended to put up the rent if the project went ahead so, after only nine months, they moved again - to what became known as Observatory House in Slough. Two years later, in 1788, William prudently married the owner's daughter, and their only son, John, who also became a famous astronomer, was born in 1792.

The new telescope was to be 40-foot long with a 48-inch mirror, but this would cost big money. George III was approached and came up with £2000 and later, when the project over-ran its budget, a further £2000, plus £200 a year to cover maintenance and £50 for Caroline, as official Assistant, so he did them pretty well. As the telescope grew it caused great interest far and wide. While the tube was still lying on the ground, it became a popular pastime to walk through it and on one occasion the king was seen taking his prelate by the hand, saying 'Come my Lord Bishop, let me show you the way to heaven.' Casting and polishing the mirror caused major problems but, at last, in 1789, all was ready and on the very first night Herschel discovered two new moons of Saturn. (The 6th and 7th, Mimus and Enceladus) Naturally he was overjoyed but sadly the great telescope never really fulfilled his expectations. It was very big and cumbersome, needing a lot of men to operate it, the heavy mirror took a long time to adjust to temperature and tarnished quickly, needing repolishing, but above all it was soon apparent that many of the misty objects he had observed could not be resolved into stars, no matter how big the telescope. Nevertheless the great 40-foot remained in occasional use until 1815 and no bigger telescope was built until 1845. (Lord Rosse's 72-inch, at Birr Castle.)
A list of Herschel's discoveries (prepared by his son John) follows this article. Although his work touched every known aspect of the astronomy of his day, he is particularly remembered as the first to attempt to probe the stars in depth. His attempt to measure their distance (first achieved by Bessel in 1837) led him to the discovery of some 800 binary stars, where none had previously been known. His expertise at assessing the brightness of stars resulted in the discovery of literally dozens of 'variables', where only two (Mira and Algol) were then known. He rightly believed the Sun to be a typical star and, while studying its spectrum in 1800, he not only noted that all the colours had different temperatures (red being the hottest) but that beyond the red, the temperature was even higher-thus discovering Infra-red rays. His attempts to categorise the types of nebulae and to arrange them into some form of evolutionary sequence was an amazing leap of imagination, and a completely new concept. By laboriously 'gauging' the heavens he determined the disc shape of the galaxy, and suspected that many of the objects he observed lay beyond its confines. Further, he had appreciated that observing at great distances meant looking back in time, and he famously remarked - 'I have looked further into space than any human being did before me. I have seen stars whose light it will be proved has taken two million years to reach us.' The truth of this remark could not be proved until more than a century after his death. (Edwin Hubble 1924.)

Herschel was knighted in 1816 and became the first President of the Astronomical Society of London (now the Royal Astronomical Society) in 1820. He died on 24 August 1822, and was buried under the tower of St Laurence's Church at Upton, Slough.

In conclusion, it is interesting to speculate on how many of the separate branches of astronomy to-day can trace their origins back to the pioneering work of this one brilliant man who, single-handedly, changed the whole course of astronomical thinking throughout the world. Elegantly expressed in his epitaph in Upton Church -

'Coelorum Perrupit Claustra' - He broke through the barriers of the heavens.

William Herschel's Discoveries.
1. A new planet and two of its satellites.
2. Over 800 double stars.
3. Over 2900 Nebulae.
4. The complete resolution of every part of the Milky Way into stars.
5. The gaseous nature of the Sun's luminous surface.
6. Two new satellites of Saturn.
7. The period of rotation of the ring of Saturn.
8. The independence of the heating and illuminating power of the sun's rays.
9. The co-incidence of the periods of rotation on their axes of certain satellites of Jupiter and Saturn with their time of revolution round their primaries - and the extension of the analogy of our Moon to all secondaries.
10. The true heights of the Lunar mountains. (Much misconceived by former astronomers.
11. A peculiar class of siderial objects, called by him Planetary Nebulae.
12. Double stars with contrasting colours, and many extraordinary facts regarding the colours of single stars.
13. Large tracts of loose nebulosity in the heavens, unconnected with stars.
14. Occasional irregularities in the distribution of the belts of Jupiter.
15. Distinction between the Space Penetrating Power and other properties of telescopes (eg. Resolution)
16. The variability of the star alpha Herculis and many other variable stars

The Earth's Weather - October 2002 - Brian Colthorpe

This talk aimed to briefly consider how the Earth's atmosphere works in basic processes of energy input, the roles of key gases in the atmosphere an

d the interplay with geography, and then attempting to put this together in a consideration of the atmosphere as a dynamic system.

The talk started with a review of a number of basics of the Earth's atmosphere including the composition of the Earth's dry atmosphere in terms of gases by volume, noting the importance of water vapour, to be discussed later. The Earth's atmosphere was also compared with the atmospheres of the other terrestrial planets.

The atmosphere was then considered as an energy system, with the principal input from the Sun and the distribution of the energy, through the atmosphere to its arrival at the surface and the heating of land and water. This also involved looking at the modifications to the heating process by surface albedo, local relief and height.

Having summarised the basics, the dynamics of the atmosphere were then reviewed, starting with cloud types and cloud formation, then moving onto the causes of winds (i.e. with the development of high and low pressure systems) locally, regionally and then to global wind systems.

The meridional atmospheric circulation was then reviewed looking at various models of global winds in three dimensions, then moving onto air mass dynamics, and how the source area of an air mass and its subsequent modification, usually in passage over oceans, is an important factor in weather forecasting.

The talk concluded with consideration of the depressions, and particularly at how they affect the British Isles.

The Star of Bethlehem - November 2002 - Anthony Fanning

Today there is a strong belief that the Biblical story of the 'Star of Bethlehem' might have had its origins in a Triple Conjunction of the two major planets, Jupiter and Saturn, which occurred in the year 7BC. The following notes from the talk Tony gave on 8 November 2002 set out the case in support of this theory.

Timing

As neither the year nor the date are recorded in the Gospels, what clues do we have?

·Jesus was born during the reign of Herod the Great, who is believed to have died early in 4BC. There was an eclipse of the Moon shortly before his death.

·There are reasons to believe our present Georgian Calendar, set up in AD525 by Dionysius Exiguus in an attempt to establish the date of Christ's birth, is at least five years wrong.

·The Great Taxation, which brought Mary and Joseph to Bethlehem, was ordered in Rome in 8BC.

·The birth of Jesus must therefore have been between 8 and 4BC

·If it was at least two years before Herod died (to allow for the slaughter of innocent children) and perhaps a year after the taxation was ordered in Rome, 1500 miles away, the most probable dates become 7 or 6BC.

Astronomical Phenomena

Two thousand years ago the word 'Star' was used for virtually all astronomical objects, planets, comets and so on. Remembering that the Wise men (the Magi) were astrologers who studied the sky in order to interpret its signs, the word 'sign' might be a better name for what we are looking for. The unusual 'stars' or 'signs' that were recorded (mostly by the Chinese) over that period are :-

• 'A comet without a tail' (probably a nova) in Capricornus in March of 5BC.
• A nova in Aquilla in April of 4BC (both too late)
• Halley's Comet in 12BC (too early)
• Lunar eclipses on 13 March 4BC and 10 January 1BC.
• A Triple Conjunction of Jupiter and Saturn between May and December 7BC.
• A spectacular conjunction of Jupiter and Venus in Leo on 17 June 2BC.

Sightings of the 'Star' or 'Signs'

According to St Matthew's Gospel (which contains the only mention of the Star in the New Testament) the following points arose concerning the 'star' or 'sign'.

·The Magi saw the 'Helical Rising' of the planets. (Just visible at sunrise, before the light became too strong) After this the planets would have become more and more visible each morning.

·The sign was sufficiently significant to cause the Magi to set out on the long journey across the desert to Jerusalem.

·The sign apparently disappeared during the journey. (ie. the planets separated)

·The significance of the star/sign was apparently not noted by Herod and his advisers, who were not astrologers.

·The sign re-appeared to the Magi while they were at Jerusalem, and seemed to point the way towards Bethlehem. (Matthew says 'went before them'.)

·It eventually 'stood over' Bethlehem. (ie. it was very high in the Sky.)

Dates of the 'Triple Conjunction' events in 7B

• Helical Rising. Jupiter - late February. Saturn - early March.
• 1st Conjunction - 27 May
• Acronychal Rising (Rising at Sunset) - 15 September
• 2nd Conjunction - 3 October
• 3rd Conjunction - 1 December (Note - the planets hardly separated at all between the 2nd and 3rd conjunctions.)

Astrological Significance

Although the planets Jupiter and Saturn (the two most powerful planets, with Jupiter the sign of Kingship) never came closer to one another than about 1%, astrologically their conjunctions would have been of immense significance. With the Helical and Acronychal risings both associated with 'birth' and all the conjunctions occurring in the constellation of Pisces, the zodiacal sign particularly associated with the fortunes of Judaea, everything pointed to the Birth of a King (the expected Messiah) in Israel. While we have no proof that the Magi (the 'astrologers' in modern translations) came from Babylon, this is strongly supported by the discovery of an astronomical tablet at Sipper, on the banks of the Euphrates, which contains a reference to the Triple Conjunction. (Although not exactly in those terms!)

Other Possibilities

Despite the strong likelihood that the Triple Conjunction was the star/sign that gave rise to the 'Star of Bethlehem', a case is frequently made for other explanations eg. a comet, brilliant meteors, a supernova, Venus and so on. All these might have been possible, and we cannot rule them out, but without positive records we can never be sure.

Conclusion

Many scenarios concerning the movements of the Magi could be devised to fit comfortably with the timing of the astronomical events discussed. Although we shall never be certain what is was that the Magi saw, which caused them to set out for Jerusalem, the Triple Conjunction of the two most powerful planets, (with Jupiter the sign of 'Kingship') in the constellation of Pisces (associated with the fortunes of Judea) does appear to be one phenomenon which fits all the facts and THAT WE KNOW DID HAPPEN.
OR - Could it indeed have been a miracle ?

Notes
1. Astronomy Now (Dec 2002) has a good article on 'The Christmas Star' by Carol Scott, which agrees with the above.

2. There is however a rival theory, based on Herod dying after the Lunar eclipse of January 1BC. This would tend to support the idea that the 'Star' was the spectacular conjunction of Jupiter and Venus in Leo which occurred on 17 June in the year 2BC !

Galileo Galilei - Dr Allan Chapman - January 2003

We were delighted to welcome Dr Allan Chapman, Head of Faculty of the History of Science at Oxford, to address the January meeting. Many thanks to Tony and Bruce, who made the excellent arrangements for this enjoyable evening.

Eton College kindly made the Edgerton Lecture hall available for the occasion, so we were able to extend an invitation to other societies. Interest was intense, with delegates attending from Abingdon AS, Andover AS, Cody AS (Qinetiq, Farnborough), Farnham AS, Maidenhead AS, Newbury AS, Wessex AS, Wycombe AS, Bracknell Forest U3A, Eton College, Padworth College as well as our own HAS members. All 160 tickets were 'sold' and there was an excellent turn out.

Dr Chapman gives a great lecture and projects his enthusiasm with style. His attentive audience was very impressed, showing their appreciation with both applause and a high number of quality questions. The following is a very brief synopsis. The whole transcript is some sixteen pages in length.

Outlining Galileo's biography, Dr Chapman's lecture focussed on the context in which Galileo worked and lived. Astronomy from archaic times right up the 17C had been effectively mathematical and geometrical. It had been concerned with measuring the positions of the stars and in trying to explain the apparent complex movements of the planets. The classical Astronomy was still Aristotle's 'On the Heavens'. The Copernican theory, that the Earth and Planets rotated around the Sun, merely explained their movements more simply, but was not accepted by the Jesuits nor by the conservative European universities, because it could not be proved to be true and did not fit observations.

Dr Chapman described some of Galileo's brilliant early experiments and discoveries in motion and velocity. He was in many ways the founder of modern experimental physics. So Galileo's career had made progress but at the age of forty five years, still Professor of Mathematics and Astronomy at Padua, he had published just one paper. Galileo sought fame and greater fortune to restore his family's position.

The opportunity came in 1609 with his development of the telescope from the 'Dutch Spy Glass'. He immediately recognised the commercial application of this for a maritime nation and he demonstrated the telescope to a group of Senators of the Supreme Republic of Venice - showing them ships far out in the lagoon. He was
rewarded with a pension.

Galileo then turned his invention to the heavens - mapping the Moon, and for the first time showing the planets Jupiter, Saturn and Venus as more than bright points of light. Moreover, his observations of the phases of Venus indicated to him that the planet was moving around the Sun. And if one planet moved around the Sun, why not the others ? His observations of Sun Spots offered further evidence of this.
Now a man of power, he had influential friends and patrons. However his support of the Copernican theory brought him into conflict with the Jesuits. They insisted he could not teach the Copernican theory as true unless he could prove it.

Finally, Galileo's controversial book the 'Dialogue', which strongly argued the Copernican case, brought him into conflict with the Jesuits and with the Pope. After a hearing in Rome, Galileo had to recant and was banished to his home near Florence. Here he continued to receive eminent visitors. Indeed, Milton visited in 1638 and included in Paradise Lost the couplet,
Through the Tuscan Astronomers Optic Glass, I beheld the plains of night.

In conclusion, Dr Chapman argues, Galileo has to be understood in the full historical context of his time. He lived in an intellectual society of almost obsessive legalism where there was enormous controversy about the nature of 'proof'. He described Galileo as a born and bred 'agent provocateur' who loved a scrap, but finally bit off a little too much. However, although popular imagery would see Galileo as a victim of the Inquisition, Dr Chapman's view was that even after his official 'condemnation', Galileo retained his high standing and remained a greatly respected scientist.

In Dr Chapman's words - Galileo was a man who became literally world famous for scientific discoveries in his lifetime. He was the first person to change the whole direction of science and bring into use instruments for making physical optical discoveries, that showed what worlds really were like - not just lights in the sky.

The Video and Audio recordings of Dr Chapman's lecture should be available soon.
If anyone would like a 'transcript' please email me at caroljonesuk@tiscali.co.uk