There’s nothing sinister about the title of our newsletter but just a reminder that, without dark skies at night, neither we nor future generations will be able to enjoy the wonders of the universe. And wonders there are by the billion.

In much of the this part of Suffolk we are fortunate that the darkness of a cloudless night allows even the naked eye to appreciate the beauty of the stars which make up our Milky Way galaxy. We spot constellations such as Orion, The Plough and Cassiopeia and distinguish the difference in colour between the red giant star Betelgeuse and its distinctly blue counterpart Rigel. We can track the planets night after night as they move through the celestial background, enjoy the fun of the meteor showers – shooting stars – or even catch the glint of artificial satellites as they race across the evening sky. Then there are the comets, the aurorae, the nebulae, star clusters and even the chance of

making out our nearest neighbouring galaxy Andromeda.

Of course, a modest telescope or even a good pair binoculars will bring further revelations such as the rings of Saturn, the moons and bands of Jupiter, the dense star fields of the Milky Way, the jewels of the Pleiades – Seven Sisters – and the spectacular Trapezium group of stars in the gas cloud or nebular of Orion.

These wonders have been there for billions of years and will remain for billions of years to come but, within our, by comparison, very short life time we run the risk of denying such sights to both ourselves and our children. Poorly designed street lights, unnecessary floodlighting of buildings, badly angled security lights and indiscriminate use of floodlighting for night time sports all destroy the blackness which is so essential for our enjoyment and appreciation of something which is part and parcel of our country life.

Our cities have long since been lost to the glare of the sodium lamp and even our towns, such as Haverhill, throw up a bright orange hue to be seen from miles away.

We should not take our village skies down that same dissastrous route. Careful and considerate use of lighting costs nothing but just think what losses it prevents.

Let’s get out there on those dark crisp nights, look up and take it in. The light from all those wonders has taken thousands and millions of years to reach us. Let’s not snuff it out in a blaze of luminous vandalism.

And don’t forget, Dark Matters !

Geoff Burling

Watch this space 7 years from now when the recently launched Messenger probe reaches Mercury !

"The Astronomy of the Greeks"

- Dr. Kevin Marshall.

"Constellations of the Autumn Sky"

- Dr. Kevin Marshall

"Variable Stars"

– Dr. Kevin Marshall.

"Search for Life in the Universe"

- Dr. Frank Flynn

"Constellations of the Winter Sky"

– Dr. Kevin Marshall

" How Old is the Universe"

– Dr. Keith Tritton

"Basic Observing Techniques"

– Dr. Jeffery Barham

"Dark Matter and Dark Energy"

– Dr. Kevin Marshall

"The Sun’s Power Source"

– Dr. Kevin Marshall

All meetings are held at :-

Cavendish Memorial Hall

And commence at 7.30 p.m.

Visitors Welcome.

Saturday 4^th September 2004

1.30 – 5.30 p.m.

On the Village Green

Stour Astronomical Society has received generous donations from both Cavendish Community Council and Cavendish Parish Council towards the purchase of a telescope with which we can observe after our regular meetings. We very much thank both of these organisations and look forward to being able to purchase the instrument, which will be named the "Cavendish Telescope", in the near future.

Saturday 2^nd October 2004

Institute of Astronomy

Madingley Road, Cambridge

Starting 8.30 a.m. – All Day Event

Speakers :-

Prof. Douglas Gough

Dr. Paul Murdin

Guy Hurst

Dr. Cathie Clark

Stour Astronomical Society is affiliated to the FAS (Federation of Astronomical Societies).

19 – 21 November 2004

Shrewsbury-£110.00inc. accomodation

Advice, Tricks and Tips for Observing

Info. from Frank Tobin

16 Penton Hook Road, Staines,

TW18 2PF

By Chris Strellis

One of the first things to learn is how to find your way around the night sky. This sounds like a difficult task but in fact it is quite easy and essential if the beginner is to go on and buy a telescope and search out the objects talked about in books and magazines.

There are three methods used to identify the positions of objects in the sky. These are:

Using the constellations

Alt Azimuth Co-ordinates

Celestial Co-ordinates

The first method is the visual system used to find an object associated with a known pattern of bright stars. This is used by most amateur astronomers and especially beginners. The other two methods use a co-ordinate system to give a numerical position on the apparent sphere of the night sky.

THE CONSTELLATION METHOD

Some of the brighter stars appear to form patterns in the night sky and their positional relationship to each other forms Constellations. Parts of constellations form asterisms, The Plough being an example. In this case the constellation is Ursa Major.

The stars appear to lie on the surface of a great Celestial Sphere. However, each star is actually a variable distance away from us, sometimes by a large amount if they are unrelated. Some constellations like Leo (The Lion) and Orion (The Hunter) do look rather like what they a named after but still need a little imagination. Most however have no recognisable shape but still have an apparent association with the other members of the group.

The main stars in a constellation are identified using a Greek alphabet letter, normally starting with the brightest allocated the first letter of the alphabet (alpha) then (beta) and so on. When all the Greek letters are used up then the remaining stars are allocated a number or a letter from our alphabet. A given star, for instance the second brightest star in the constellation of Orion would be identified as beta Orionis (The Greek form of Orion). The brightest stars may also have a real name for example b Orionis is also known as Rigel.

Constellations are not all the same size and are defiantly not the same shape so it is difficult to know where one ends and another begins. Star charts will show where the borders are but it is not really important to the astronomer. You only need to find the main stars that make up the constellation to identify the approximate area of sky to be searched for other objects.

The method used to find interesting objects in a constellation is called 'star hopping'. Star hopping involves firstly finding the constellation in which the target is located or is near. Then by finding two or more stars within the constellation, they are used as a guideline to point towards the target object. It may be necessary to use a number of stages to route out an illusive object by first finding the direction to a particular star then using that star and another to plot out the position of the target.

To become familiar with the constellations requires nothing more than a clear night and a simple star chart. As familiarity increases then a pair of binoculars might be useful to identify the fainter members of a constellation.

There will be more on Star Hopping in Part Two of this article.

THE ALT AZIMUTH METHOD

This method of finding stars and other interesting objects does not use the patterns of the stars in the sky at all. A reference is given, rather like on a map, where a grid reference or latitude and longitude references are used. The problem with using this type of co-ordinate system on the sky is that the stars appear to continuously move, from west to east, due to the rotation of the Earth.

To overcome this problem, any calculation to determine the position of an object in the sky must take into account the location of the observer and the time at that position. Although not a difficult calculation it does have to be continuously updated to keep up with the rotation of Earth.

Dobsonian telescopes are a type of Alt Azimuth mounted telescope (see previous Dark Matters article). This type of telescope is mounted on a rotating base and has a pair of bearings on the tube as well allowing it to be raised or lowered. . It will be necessary to fit angle encoders to the telescope to allow the angles to be measured. The telescope base has to be able to be adjusted so that it rotates on an exactly level surface.

Computer programs can be used to carry out the continuous calculations to tell the astronomer where to aim the telescope

Next the latitude and longitude of the observing site has to be specified. The time information will be taken from the computer clock but it must be correct and set to GMT not British Summer Time.

When the program is asked to calculate the position of an object it will display two bearings in degrees and minutes of angle. The first angle of rotation, azimuth, is measured from True North (0°) starting towards East (90°) and all the way round back to 0°. The altitude angle is measured from 0° at the horizon to 90° which is directly overhead (zenith).

The telescope is them moved in both axes until the read out from the angle encoders matches the desired object’s angle.

THE CELESTIAL OR EQUATORIAL METHOD

The problem with the Alt Azimuth system is the telescope has to be moved in both axes to track the target object as it moves in an apparent arc across the sky. The apparent arc is caused by the tilt of the axis of Earth compared to the plane of its orbit around the Sun.

This tilt is about 26° and this can be seen in the sky by finding the Pole Star. It will then be seen that Polaris is not directly overhead but about 26° towards the north. The axis of rotation of Earth (the imaginary line passing through the north and south poles), points to Polaris or at least very close to it.

Therefore all the other stars appear to rotate around Polaris. As this axis is tilted at 26° from the plane of the Solar System, the Celestial Equator (Earth’s equator projected out to the Celestial Sphere) is also tilted at 26° so there are 90° + 26° (116°) from the southern horizon to Polaris.

This angle of elevation known as Declination and is measured as 90° from the Celestial Equator up to Polaris and -90° from the Celestial Equator to the point in the southern sky where the south pole points to.

The advantage of this system is that a star or other object can be tracked across the sky by driving the telescope in one axis only. This is achieved by using an equatorial mounting. The difference between an equatorial and an Alt Azimuth mounting is that the equatorial rather than having its rotation bearing level, has it inclined to the celestial pole. This allows the telescope tube to rotate around the same axis as the Earth's axis. By driving the telescope at 1 revolution per 24 hours it will rotate at the same speed as the Earth and track the star it is pointed at.

Declination works on the Celestial Sphere much in the same way that latitude does around the globe of the Earth. Right ascension is analogous to longitude measured around the Earth in the east-west direction.

In the sky with right ascension (celestial longitude) we need some point to play a similar role to that of Greenwich for terrestrial longitude. Astronomers have chosen the Vernal Equinox to define the starting point for the measurement of right ascension. The Vernal Equinox is the point where the sun appears to cross the Celestial Equator at the beginning of spring. It is therefore one of the two points where the Ecliptic, the apparent path of the Sun across the sky, intersects the Celestial Equator as shown in the figure.

Right ascension in many ways works somewhat differently than longitude. First, unlike longitude, right ascension is always measured eastwards from the Vernal Equinox. There is no west right ascension in the sky.

Secondly, we do not measure right ascension in degrees as we do, longitude, but rather in hours. One hour of right ascension corresponds to 15° of celestial longitude, and there are 24 hours all the way around the sky eastwards from the Vernal Equinox, back to the Vernal Equinox again. Each hour is subdivided into 60 minutes, and each minute into 60 seconds, just as if we were measuring time instead of eastwards angular distance but we are still talking about an angular distance measured around the Celestial Sphere.

On Earth we have constant longitude on lines stretching from pole to pole - the meridians of longitude. However, we don't talk about meridians of right ascension. The corresponding term in the sky is hour circle. An hour circle stretches from the North Celestial Pole to the South Celestial Pole. You have the same right ascension all along an hour circle. So in the figure, hour circles are shown for right ascensions of 0, 1, 2, and 3 hours. (Actually only half of each hour circle is shown, the half lying in the Northern Celestial Hemisphere.)

So after all of this, an object’s position in R.A. and declination can be looked up from a Star Atlas or Computer Planetarium program and the telescope moved accordingly. The read out of position coming from the telescope’s setting circles or digital setting circles. More of which in part two.

*********************************

Do you imagine yourself at the eyepiece of one of the largest telescopes in the world? Or on a mountain-top in an exotic place with the deepest velvet sky overhead studded with brilliant southern stars? Strangely, this is not how professional astronomers spend most of their time.

An office desk or a computer keyboard are the usual day to day scene. There are perhaps only 1000 research and related jobs in astronomy in the UK so, while it is possible to get a good job, the competition is really fierce. Outlined below is the usual route through school and university and on to postgraduate research. There is no short cut; six or seven years at University are required to reach the point at which you can apply for research posts.

You do not need to have a GCSE in Astronomy. It is far more important to have a really good basic education, including good grades in English, Maths and Science. Your choice of the other subjects can reflect your other interests but a foreign language might be very useful as you may be travelling a lot and attending international conferences! It is essential that you obtain a top grade in Physics or Double Science, and also in Maths. You will be studying these subjects further.

You will need to include Physics and Maths in your AS choices, along with at least one other subject. Maths and Physics must be continued to A2 Level. Again even at this stage you do not need to study any astronomy so your third subject could be another science such as Chemistry, Biology or Geology, or it could be Further Maths.

There are over thirty universities which offer first degree courses with some astronomy content. A list follows overleaf. However a straight Physics or Maths degree would also be an excellent preparation for a career in astronomy and would be a safer choice because these will prepare you for a wider variety of jobs. You will not have to specialise too early and will have openings for other careers if you do not finally make it into astronomy.

Other courses with a Maths component or some engineering are also suitable but it is important to make sure that there is a high content of Physics on the syllabus. Most universities now offer a four year MPhys (Master of Physics) or Msci (Master of Science) as a first degree and you should seriously consider this option if you wish to carry on after your first degree to study postgraduate astronomy.

Many university departments have some astronomy research in progress and some have access to an observatory. If you live, eat and breathe astronomy, you will be careful to choose a course that allows you to be involved in such activities, perhaps through the University Astronomical Society or during optional third- or fourth-year projects.

Your final choice of a place will depend on you personal preference for a particular location, on your expected A Level grades and on the course content. Discuss all these factors with parents, teachers and with the staff of the University concerned. You will probably visit several places and get a "feel" for the place which is right for you.

When your first degree course is over, you can begin to specialise in astronomy. Some graduates like to study a one-year MSc course, especially if their first degree

contained little astronomy. However most people apply directly for a PhD research place (to study to be a "Doctor of Philosophy"). It takes three years to carry out the research necessary to write a thesis, so you should make sure that your chosen university has research projects in which you are interested and can become fully involved. Often this period determines which branch of astronomy you will study for the rest of your life! You can remain at the same university where you studied as an undergraduate or you could apply elsewhere. To be accepted into a department to do a PhD you must have a very "good" first degree – a "First Class" or possibly an "Upper Second Class" Honours Degree. Without this you will have great difficulty getting funding from one of the grant-giving bodies such as PPARC (Particle Physics and Astronomy Research Council). However it is sometimes possible to find a place on an MSc course with a lesser degree and work your way up from there. Some PhD students are funded by themselves or their families, by university scholarships or even by their own part-time work.

These three or four years give you the chance to show how well you can carry out original research. It provides the opportunity to make discoveries in your chosen field. Your supervisor and other members of the department will follow your work, helping to plan it and to take the observations, but the bulk of the work will be your own. Finally you will write a thesis – the report in which your findings are published.

This is examined and if it is passed it will give you the title "Dr". This is now the beginning of your professional career; you will have proved your worth and will be looking for your first appointment.

It is now almost unknown for newly qualified PhD’s to start straight away on a permanent contract. They usually serve a two or three year period of research in a university department as a PDRA (a Post-Doctoral Research Associate or "Research Fellow"). Such posts are quite hard to secure. At this stage many people leave astronomy to find work in computer-based industry, telecommunications, aerospace companies, publishing or teaching.

A PDRA will be a member of a team pursuing a particular line of research, but he/she will probably not have lecturing duties yet. The job will be salaried and represents the beginning of a research career. How well you perform in these two or three years may well be important in securing that first permanent post.

At this stage, only about a quarter of the newly qualified PhD’s make it through to permanent employment in astronomical research. This sound like a grim statistic but it is true that only the very best researchers stay with astronomy all their lives. Jobs are few and far between. They may be abroad, they may be temporary. Those who are truly determined can still find worthwhile and rewarding astronomical work. However, unemployment is rare among those who do drift off into other interests and careers. Their strict training in physics, maths and computing skills combined with their experience of team work equips them well for many other jobs.

This list is not exhaustive, but it is an indication of the number and variety of courses on offer. The UCAS handbook should be used to give a more up-to-date picture. To get full details of a particular course you are encouraged to contact the university in question and ask for the department’s prospectus.

Queen’s University Belfast

Manchester University

University of Birmingham

University of Manchester Institute of Science and Technology

University of Bristol

University of Newcastle-upon-Tyne

Cambridge University

University of Nottingham

University of Dundee

The Open University

University of Durham

Oxford University

University of East Anglia

University of Paisley

University of Edinburgh

University of Reading

University of Essex

University of Sheffield

University of Glamorgan

University of Southampton

University of Hertfordshire

University of Surrey

Keele University

University of Sussex

University of Kent at Canterbury

University of Wales, Aberystwyth

Kingston University

University of Wales, Cardiff

University of Central Lancashire

University of Warwick

Lancaster University

University of York

University of Leeds

University of Leicester

Liverpool University

Liverpool John Moores University

Imperial College London

Kings College London

Queen Mary and Westfield College, London

Royal Holloway College, London

University College, London

Loughborough University

*********************************

If you have read Steven Hawking’s "A Brief History Of Time" you may remember his anecdote where a distinguished scientist, possibly Bertrand Russell or Thomas Huxley, gave a public lecture in which he described how the earth orbits the sun & how the sun orbits the centre of a vast collection of stars called the galaxy. At the end of the lecture a little old lady at the back of the room got up & said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise." The scientist gave a superior smile before replying: "What is the tortoise standing on?" "You’re very clever, young man, very clever" said the old lady "But it’s turtles all the way down"

The turtle theory apparently originated with a Hindu myth; as an attempt to explain the nature of the Universe it may strike us as eccentric, but the concept of scientific investigation - observation, leading to theory, leading to predictions about further observations - was then unknown. In the beginning it was inevitable that ideas about the nature of the world, the sky & the objects contained within it would be speculative & highly imaginative, since extracting patterns of behaviour from a tangle of natural phenomena must have been difficult. The apparently capricious occurrences of fire, flood, storms, famine & drought would look much more like the doings of some moody being with superhuman abilities. However, the sky would have provided the best examples of order & continuity in an unpredictable world. After the regular daytime transit of the sun, night would bring the moon & stars, rewarding observation with gradually more distinct patterns of behaviour, thus the beginnings of cosmology took shape Without exception early theories invoked gods as the moving force behind the changing face of the night sky; our relationship to these beings was more important to earlier civilisations than the more utilitarian view that we take today, but eventually such considerations - how we use astronomy for navigation, timekeeping & so on - took precedence. It could be said that we began to take less interest in who was running things & more in simply how they ran.

One of the biggest forces changing our attitude was the improvement in technology. In many ways the history of mankind is the history of technology; changes in weapons, travel, communications, farming, medicine etc. etc. have all impacted on every society in the world & these changes are increasing exponentially - they are building on themselves. It is worth reflecting that the reason we seem so clever compared to our ancestors is that we are standing on a great pile of knowledge, which is available to more & more of us. In astronomy the manufacture of lenses, increasingly more powerful & accurate, led to better observations & the heavens rapidly became an ever more intriguing & fruitful subject for investigation. This obviously led to greatly improved cosmological models, as the various theories could be tested against new & more detailed observations. So, here are a (very) few landmarks in the history of cosmology :-

Aristotle 340 B.C.

Naked eye observations

Earth round & approx. 50,000 miles. diam.

Ptolemy 200 A.D.

Naked eye observations

Earth centre of 8 orbiting spheres containing

sun & moon, 5 known planets & stars in outer sphere.

Copernicus 1514

Naked eye observations

Sun centre. Planets in circular orbits.

Kepler/Galileo 1609

9x refracting lens telescope

Planets in elliptical orbits. Star static.

Herschel 1790ish

18.8 inch reflecting telescope

Solar system part of Milky Way galaxy

Hubble 1924

100 inch reflecting telescope

Existence of other galaxies

Hubble 1929

100 inch reflecting telescope

Galaxies always moving apart

Penzias & Wilson 1965

Radio telescope

Background microwave radiation supports big bang

In the last 40 years advances in all technologies - computing, electronics, metallurgy, photography, to name a few - have accelerated enormously, often feeding off each other, leading to huge advances in astronomy & an ability to analyse not just the light from the heavens, but the full range of the electromagnetic spectrum pouring in on us . Even better, with telescopes in space the masking & distorting effects of our atmosphere are removed. Paradoxically, this welter of information has led to even more competing theories about the Universe; as can be seen above there used to be plenty of time for ideas & observations to interact, nowadays cosmology & astronomy are playing an accelerating game of catch-up - in the last few weeks Mr. Hawking has revised his ideas about just how black black holes are. Nevertheless the essential big bang, ever expanding Universe has had no serious competition, all observations seem to confirm it, the doubts arise at more fundamental levels.

One of the most interesting examples of astronomy dramatically changing cosmology was the discovery of red shift in the spectra of stars in other galaxies. When light from a star is broken down into its different wavelengths it produces a pattern typical for that type of star, with absorption lines corresponding to particular elements. It strikes me that it looks rather like a DNA pattern, & in the same way identifies the star family it belongs to. What was surprising was that the patterns were identical to known types, but all shifted to lower frequencies - red shifted. It was also found that the further away the galaxy the more the red shift. The simplest explanation (& science always takes the simplest explanation!) is provided by the Doppler effect, which implies that all galaxies are moving apart & the further apart they were the faster they were separating; a good way to imagine this is to think of a spotty balloon being inflated & visualise what happens to the spots. Thus the idea of an ever expanding Universe took root, which led directly to the big bang model we use today.

The important thing to remember is that all cosmological theories are just that & no more. They are all dependent on astronomical observations & if the observation is accurate & consistent & contradicts the theory, then out goes the theory. In practice what happens is that the best theories survive in their broad outline, approximating to the better, more detailed theories that supplant them.

Now suppose the turtles were invisible ……

Catching a Falling Star

While observing a supernova in a distant galaxy with the FORS instrument on ESO's Very Large Telescope at the Paranal Observatory (Chile), astronomers were incredibly lucky to obtain serendipitously a high quality spectrum of a very large meteor in the terrestrial atmosphere.

The VLT spectrograph provided a well calibrated spectrum, making it a reference in this field of research. From this spectrum, the temperature of the meteor trail was estimated to be about 4600 degrees centigrade.

The serendipitous spectrum reveals the telltale meteor emissions of oxygen and nitrogen atoms and nitrogen molecules. The VLT spectrum was the first to reveal the far red range where carbon emission lines are predicted; the absence of the lines puts constraints on the role of atmospheric chemistry when life started on earth.

Because the VLT is tuned to observe objects far out in space, it focuses at infinity. The meteor, being "only" 100 km above the telescope, therefore appears out of focus in the field of view.

For those interested in purchasing a telescope there are a couple of good suppliers in the area :-

Green Witch,

Unit 6, Dry Drayton Industries, Scotland Road, Dry Drayton, Cambridge, CB3 8AT

Tel: 01954-211288

Sneezums,

10 Cornhill,Bury St. Edmunds, Suffolk,

IP33 1BH

Tel: 01284-755210

Beagle 2

NASA

Jet Propulsion Laboratory

European Space Agency

Institute of Astronomy

Mullard Radio Astronomy Laboratory

Jodrell Bank

Royal Observatory, Greenwich

European Southern Observatory

National Space Centre

TheSociety for Popular Astronomy

Stour Astronomical Society meets on a monthly basis in the Jubilee Room of Cavendish Memorial Hall on the first Tuesday of every month at 7.30 p.m.

At each meeting an illustrated talk will be given either by Dr. Kevin Marshall or by a guest speaker. Dr. Marshall is a lecturer with the University of Cambridge board of continuing education, an Open University tutor and is a founder member of the Stour Astronomical Society.

The Society was founded in 2003 to provide a focal point for amateur astronomers of all levels of interest and ability to meet and share their enjoyment of the night skies. It is anticipated that members will be drawn from nearby towns and villages in the Stour Valley area.

It is hoped that at future meetings some observation will be possible on clear nights and members are invited to bring telescopes or binoculars when weather conditions permit.

We very much welcome new members to the Stour Astronomical Society. Membership is £12.00 per year.

Visitors & Members’ Guests are also very welcome - £1.50 per evening.

"Dark Matters" is the newsletter of the Stour Astronomical Society (S.A.S.).

Secretary – Geoff Burling

01787-281584

Chairman – Kevin Marshall

01787-249534

Webmaster – Chris Strellis

Treasurer – Colleen Sarratt

Saturn courtesy of Cassini & NASA