Herschel Astronomical Society
Calendar of Meetings
Due to Coronavirus Restrictions Meetings will not take place at Eton Until Permitted
In the meantime Members will be informed by email of the location of meetings.
Please make sure we have your email adress
Meetings are usually held at Marten Building, Eton College
7.30 pm, 2nd Friday of each month
|10 Sep 2021
||Brian + Ian
|08 Oct 2021
|12 Nov 2021
||Practical Astronomy 1
||Brian and Ian at Switchback Road
|10 Dec 2021
||Christmas Party + Quiz and Observing
||Brian and Ian at Switchback Road
|07 Jan 2022
|11 Feb 2022
|11 Mar 2022
|08 Apr 2022
|13 May 2022
Visits and Public Viewing Evenings
|Sat 10th August 2019
Perseid Meteor watch at 45 Switchback Road - from 9:30
Meetings are open for anyone to attend but if you are not a member we would ask for a contribution of £2 towards the costs involved in running the meeting.
Download Example Magazine in PDF format
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
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
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
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
14. Occasional irregularities in the distribution of the belts
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
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
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
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.
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.
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
·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
- 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.)
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!)
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.
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 ?
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
Galileo Galilei - Dr Allan Chapman - January
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
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
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 Video and Audio recordings of Dr Chapman's lecture should
be available soon.
If anyone would like a 'transcript' please email me at firstname.lastname@example.org