More stories from Pam Draper

Radio Galaxies

In 1963 astronomers Roger Lynds and Allen Sandage concluded from research that hot violent explosions in the nuclei of certain galaxies were the cause of radio emissions from these galaxies.  These explosions were the possible result of the gravitational collapse of at least one hundred million solar masses of gas or stars.  Resulting in the spiralling of the electrons close to the speed of light in a strong magnetic field.
This is known as Synchrotron Radiation.  Particles moving close to the speed of light are called Relativistic Particles.

When mapped at radio wavelengths, narrow beams or jets of matter travelling at close to the speed of light are seen emerging from the galactic nucleus.  M87 in Virgo is a good example of a radio galaxy expelling matter along a jet and is believed to be powered by a source of radiation such as a central black hole.  Centaurus A is another and is the nearest radio galaxy to Earth.  Others are Cygnus A, M84, 3C75, 3C310, 3C449, NGC 1265, NGC 6251, and Herc A.
These jets of emission extend outwards hundreds of thousands, often millions, of light years either side of the galactic nucleus, others are swept backwards as the galaxy moves though the intergalactic medium.  They often appear twisted and knotted, some expand out into lobes following magnetic fields within gas clouds surrounding the galaxy.
The immense forces at work within these galaxies is phenomenal and much is still not fully understood about them.

Why not try Thinking about Gravity?
I did ­ Can anyone help?
The curvature of space causes light to bend relative to the viewers position, this curve is called a Geodesic.  Gravity distorts light around a body or mass ­ stars, galaxies etc.  The curvature of space around that mass has to be thought of as being in many directions.
Gravity seems so compatible with light that it occurred to me, and this is just an idea, that maybe these gravity waves ride with or on light (electromagnetic) waves, like a ship at sea, oscillating and undulating within the cosmic medium.  Current research aims to find these gravity waves produced from cosmic explosions, pulses even from the Big Bang itself!
If light reaches us from long ago, what about the essence of gravity?
Are we seeing its effects from as old as time also?  How long is the life of gravity?  If light can travel indefinitely at 186,000 mps, where does that leave gravity?
If gravity effects light ­ and the speed of light effects time ­ does gravity have any effect on time?  I know it does near a black hole.  Ultimately what form does gravity take?
Also I ask myself do I have the faintest idea what I am talking about?
Thinking about gravity?  I can recommend it to give you indigestion!

Carl Sagan   1935 - 1997

As a teenager in the seventies I watched Carl Sagan's excellent TV series COSMOS and the Royal Institutions Christmas lectures he delivered and thought how wonderfull and exciting he found the subjects of space and astronomy.
Carl Sagan was born in New York City and gained a PH.d from the University of Chicago in 1960. In 1968 he became a professor of Astronomy and Space Science at Cornell University. An author and educator he wrote several books and many scientific papers. Carl Sagan writing always reflected his broad interests amongst them, the nature of the planets and their atmospheres, the origin and nature of life on earth and the possibility of life on other planets. In 1978 he won the Pulitzer prize for his Book "The Dragons of Eden" about the evolution of the human brain.
I feel it particularly sad at his passing before he could know from the Mars Pathfinder mission results as to wether there was, or is life on Mars and the definitive possibility of it elsewhere in the universe. In sure this man will be sadly missed by many.

Pam Draper
 

I too, like Pam, was very sorry to hear of the death the other week of Carl Sagan.  I too, can remember his Royal Institution Christmas lectures and his famous 13 part TV series, COSMOS, which still stands today as the most watched scientific show ever seen world wide.
Recently I saw him on television in a program about the ?life* found in the Mars rock ALH840001 and I was shocked and saddened at his appearance.  Only his voice gave him away, he had aged many years with the bone disease and I would not have recognized him without the on-screen caption.
He was one of a select few; scientists who could put over ideas to the general public in a way which ordinary folk could understand.  Carl did not look like the scientist he was, he looked more like a regular guy next door.  He had a gift for writing and I have his books COSMOS and also COMET which he co-wrote with his wife Ann Druyan.  I also have his best seller fiction book, CONTACT, the story of the first radio message from ET?s and what the message means for mankind.

For many years he played a leading role in the American space program.  Being involved in the Mariner, Viking and Voyager expeditions to the planets for which he received NASA?s Medal for Exceptional Scientific Achievement as well as many other awards and prizes for his work.
One of his greatest triumphs was helping to end the Cold War by his discovery of The Nuclear Winter by which a nuclear exchange between the super powers would cause a global freeze by the amount of smoke and dust thrown up.  He, along with a colleague, proved that no one could win a nuclear war because of the damage to the eco-system.  Most of the planet?s life forms would be destroyed along with most of us!  In either the fires caused by the heat of the explosions or the years of dark and cold following until the smoke and ash had fallen out of the atmosphere.  It has been estimated it took the Earth nearly a million years to fully recover from the asteroid impact 65 million years ago.
Carl Sagan along with a few others make science interesting for everyone.  We will miss him.

Ivor Clarke

Change?  What Change?
By Ivor Clarke

The other day while I was travelling to work in the car, I heard a piece on the Radio 4 program ?ToDay* which made me forget all about driving. How I finally arrived at work (I was on auto pilot I suppose), I can?t remember.  The  interview was with an archaeologist who was talking about recent finds which have been made in Ethiopia, of a selection of stone tools used by our early ancestors.  These tools are 200,000 years older than any previous known similar objects and set the clock back to well over a million years in which these tools where made. . . .
Now let?s think about this for a moment, these tools where made without any change or modification in their design for over a million years!

This is what astounded me, people had made the same type of tools; one a type of Stone Age Stanley knife (which can be very sharp for a short while after being made), for cutting skins and meat and the other an axe type of tool to be held in the hand; in exactly the same way for 1,000?s of generations.  They had used the same type of stone chipped in the same way, so much so, that if samples of the tools were put side by side, from the earliest to the latest periods, they are indistinguishable from each other!
How is this possible?
How is it possible to continue to manufacture the same tools without modification over such long periods of time?

Well, to start with the tools worked well, they were easy to make and could be made new for each  job.  So considering the laid back type of lifestyle of these people, change was not a pressing requirement.  Indeed evidence now suggests that the average amount of time worked for these type of hunter gathering people was about 19 hours a week!  The rest of the time was spent having a good time with their friends and family.  Life was easy, with plenty of food to pick, if it was not possible to catch and kill any.  In general, we work harder than our hunter forebears.  Among the !Kung Bushmen of the Kalahari, once regarded as the classic model for hunting societies, one day of ?gathering* provided three days? food, leaving plenty of time for visiting, entertaining, and partying.  If the hunt failed there was an abundance of mongongo nuts providing each person with the protein equivalent of 1lb of meat a day.
But what?s all this got to do with astronomy?

Well, we have made several attempts to try to find other civilizations on other planets around other stars and failed.   In some ways it?s not surprising if the other lot on a local planet are enjoying themselves sunbathing and swimming so much, then popping down to the local tree and giving it a good shake to get dinner.  What incentive have they for making a change, inventing civilisation and technology and radio telescopes?  Why change and make life more difficult and complicated?
Also we have no way of knowing where we stand in the cosmos intelligence league, are we as intelligent as other races or have we a long way to go?  If we are an advanced species who has high intelligence, what does it tell us about the speed of our progress over the last 200 years or so.  The rate of change has been like a vale of fog lifting, the more it clears the more there is to see and understand.  Does our speed of progress lately equal other beings?  Its hard to believe we could go much faster, but as we have seen, we did progress very slowly once.

So what happened to us?  And just because a species is clever, it is not necessary true that a technological society will develop.  Dolphins are smart but not too many have yet mastered holding a mobile phone.  OK, so this is not fair and rude to dolphins, but you see my point.  Dolphins have for millions of years been swimming in our oceans and could never receive or send a message to another planet.  How many times will, is, this happening now in our galaxy?
The species must be able to pick up objects and use them, to make TOOLS.  The human hand is unique, nothing can match out ability to pick up and manipulate objects.  This is, along with speech, the main reason for our dominance over the rest of the species on the Earth.  We are tool makers and users.  Of cause, not all tools are complicated, some are simple.  A few animals and insects make and use tools to help them do certain jobs, like poke things out of holes or brake open nuts and such like.  But that?s all, no progress.  This is what we did for a million years.  And don?t forget these people where just as clever as us with the same size brains.

Can it be possible that intelligent life exists and has never moved on from a primitive existence.  If plenty of food is near and the weather fair, what is the motivation for change?  If the food is plentiful and the people are not struck down by disaster of one form or another, attack by other tribes, wild animals, disease, earthquakes, fire or flood, life could go on form many millennium with out much change.

It could be that the drastic changes in Earths climate which caused the ice ages was the starting pistol for our rise in technology with the invention of farming and the plough.  With fields sown, you can?t move about too far or you will loose the crop, so you have to stay near and build a home so as to benefit from the hard work of land preparation.  From this one idea of producing your own food by yourself instead of just looking for it has grown our society.
Sometimes it?s hard to imagine life without electricity.  Only when on a holiday camping or during a power cut do we have to get along without it for a short while, but with out it, no radio.  So recent has been this development that we forget what a change it made to peoples lives and now we take it completely for granted, but can we be sure anything else nearby in space has also discovered it and knows how to use it for radio?

From over 60 light years from our sun,  we could now detect ourselves with present technology by the slight amount of radio noise giving off by the early broadcasts.  It would soon be obvious that the amount of radio use was increasing steadily.  Such an observation would instantly confirm the existence of a another race of technology aware beings.  Communication with them would be another ball game, but we would know we were not alone.
If it had been us on the receiving end of a radio message 10,000 years ago, we took no notice did we.  Suppose someone (something) sent us an urgent message which arrived, say, only 80 years ago.  What did we do about it?  Nothing.  No one was listening.  This is a problem, how do we, how can we know if we have been sent messages in the past?  All we can hope is that we don?t miss the next one.
Would we now be doing all we can to find other ET life if we really thought the film ?Independence Day* bore the slightest resemblance to the truth.  We don?t expect any trouble from them out there.
Do we?

Stars by Daylight
by Mike Frost

As you probably know by now, I?m a great fan of the Guardian newspaper?s idiosyncratic ?Notes and Queries* column, where readers pose questions, serious and silly, for others to answer.  If the format sounds familiar, it may be because most other papers have copied it over the past few years ? but the Guardian started the trend.  Actually, ?Notes and Queries* was originally the name of a magazine feature from the middle of the last century, but the Guardian was first to revive it.

Anyway, I have been firing off occasional answers for years now; my current score is four answers published out of a dozen or so submitted. My best one was a description of an unconventional way of cleaning magnetic computer tapes (in answer to the question ?can cassette tapes really be wiped by placing them close to a magnet?* which involved the giant electro?magnet in a steel works ? and was published under the heading ?Fatal Attraction*.  But until last year I had never had an astronomical answer published ? not even when the Green Flash came up!  Then along came this:

Is it true that if you go to the bottom of a very deep well, and look at the sky, you will see the star directly above, even in broad daylight?
This was my answer, which the Guardian published the following week (they missed out the third paragraph, making me appear a lot less even?handed):
?No. In the daytime, cloudless sky is filled with blue sky light.  This is scattered sunlight, that is to say light from the sun which has bounced off molecules in the atmosphere and so reaches the observer from a random direction.  Only a fraction of light from the sun is diverted in this manner; however the sun is so much brighter than anything else in the heavens that scattered sunlight drowns out everything else in the sky except for the moon. Only when the disk of the sun is completely covered (principally at night but also during a total solar eclipse) is the sky dark enough to allow stars to be visible through it.

However, ever since the time of Aristotle, there have been persistent stories that from the bottom of deep shafts, such as wells or mines, the sky appears to be darker, and stars in the line of sight can be glimpsed.  This has never been scientifically proven - the background skylight will be bright enough to drown out stars whether one looks at the whole sky or just a tiny portion of it.  Most likely the apparent darkening of the sky is an optical illusion caused by the removal of sun and the rest of the sky from the field of view.  When the amount of light entering the eye is small the pupil can open wider and so colours appear more vivid.

So what of the stories of daytime observations of stars?  These would appear to be myths and hearsay. However it would be foolish to miss some new physical phenomenon through dogmatically reasserting the received wisdom - repeatable photographic or eyewitness evidence would be very interesting!
Marcel Minnaert?s classic book ?Light and Color in the Outdoors? (Springer-Verlag) discusses the phenomenon, and the related myth that stars can be seen in daytime in the reflection of the sky in mountain lakes.

Well, I thought that this would settle the question ? but I was wrong!  The very next week there appeared an answer from one Roz Cullinan of London:
?Some 20 years ago a cliff?fall at Birling Gap, near Eastbourne, revealed a well, dug by the Beaker people to serve as a defensive settlement.  At first the sea eroded just the bottom settlement, so one could look up the 300ft well.  And indeed the sky was dark and stars were visible.  Further cliff falls destroyed the well.?
I was intrigued!  Was Ms Cullinan mistaken, or was something going on that astronomers didn?t understand?  And how frustrating that the site from which the stars had been seen was now no longer standing.

I spent a little more time researching in Birmingham library, and came across some research done in the 1950s by J.A.Hynek, who I think must be the same Hynek who does U.F.O. research.  He calculated when Vega would culminate at the zenith, and attempted to observe the event, both by eye and photometrically, from the bottom of a large chimney ? without any success.  Fairly conclusive evidence, I thought.  Nevertheless, my editor at Astronomy Now, who was busily trimming down my Green Flash article, suggested I prepared a letter to the editor asking for any observations.  This duly appeared in the February edition, and prompted two replies.

Mike Dworetsky, from the university of London, agreed with me.  Additionally, he made the point that, even at night, you probably won?t be able to see any stars with the naked eye from the bottom of the average mineshaft, because the aperture is likely to be small, and there really aren?t so many stars visible to the naked eye.  So, if the chances are against you seeing stars by night, what price stars by daylight?  Dworetsky had an appealing alternative explanation ? dust or smoke emerging from the top of the shaft, glinting in the sunlight and so appearing to twinkle.  Well, it made sense to me!

However, David Fryman, also of London, had other ideas!  He drew my attention to ongoing correspondence in the B.A.A. journal about the visibility of planets by daylight ? a rather more practical prospect, certainly for the brighter planets, and especially so for Venus, which spends half it?s life in the brightening skies after dawn.  Mr Fryman had even managed to observe Mars, shortly after sunup, at magnitude ?0.9.  The major problem, he reported, was preventing the eye from wandering, and a fixed reference point such as a window frame was useful. The technique sounded rather like those needed to see the 3D stereograms I was so keen on a little while back.

Well, I figured it was about time I put in my two penn?orth (as we Rochdalians say) with the B.A.A. journal.  Fortunately I had a source no?one else had yet quoted ? namely the B.A.A. journal itself!  I located a discussion following presentation of a paper on ?Stars by Daylight* by Revd W.F.A.Ellison in 1916.  The discussion turned to observing Venus with a sextant, i.e. through a small (3/4 inch) aperture telescope.  Mr M.A.Ainslie reported that ?he had certainly seen Venus in the field of view of a sextant in the daytime on several occasions, but he had never been very successful in observing the planet under those conditions, nor had he ever met any navigating officer who placed much dependence on such observations*.

He was about to!  Captain Carpenter said ?he had done a great deal of surveying at sea off the coast depending entirely on astronomical observations. The officers of the morning watch were instructed to keep touch with any planet long after daylight appeared so they could get a good daylight horizon.  There is no more accurate observation than that of a star or a planet with a daylight horizon*.
So daylight observations of Venus (albeit with some magnification) were part of the naval navigational repertoire.  Daylight observations of the brighter stars and planets are possible for a while after sunrise, if you know how to keep your eyes fixed.  But daylight observations of stars at the zenith are almost certainly not possible, and are probably explained by particles glinting in the daylight.

I summarised all this into one or two pithy paragraphs, sent off an e?mail to the Guardian, and awaited subsequent editions of Notes and Queries. I?m still waiting!  Unfortunately, the gap between the original correspondence and my final summary was nearly a year, and I rather think the good chaps at the Guardian have lost interest.
Never mind ? I had a lot of fun researching my contributions to the debate.  I have always found it one of the great pleasures of astronomy that the myths of old can yield nuggets of science, and in this case I came across some completely unexpected gems.  And it seems that, in this case at least, there really is nothing new under the Sun.
 

Last week?end I located a copy of David Hughes? 1983 article in the Quarterly Journal of the Royal Astronomical Society (QJRAS 24, 246?257, 1983), ?On Seeing Stars (especially up chimneys)*. He mentions many instances of daylight stars in science and literature (Kipling and Dickens, for example), but my favourite is Sir Robert Stawell Bull, Lowndean Professor of Astronomy at the University of Cambridge. In his 1908 book ?Star Land*, he wrote ?...stars may be seen occasionally through the tall chimney attached to a manufactory when an opportune disuse of the chimney permits of the observation being made.*  The accompanying picture shows a rather stout chap at the base of such a chimney? and apparently the stout chap looks rather like Professor Sir Robert!

A COMPANION TO THE SUN?
by
WINSTON HALLET

In 1994 I took leave of my senses and made an application to the Open University to do their course on Astronomy and Planetary Science.  One of the assignments, was to write an imaginary article to the local newspaper about an astronomical event that would interest the readers without alarming them.  This is what I wrote.

A companion star to the Sun, called a Brown Dwarf as been observed in the direction of the constellation ORION.  If you go out on a clear night at about 8pm and look due south you will see four bright stars in the shape of a long oblong box which has been pushed out of shape.  Across the centre of this box you will see three bright stars in a line, this is the constellation Orion.  The top left hand star, which is a ruddy yellow colour and very bright is called Betelgeuse.  The Suns companion is a Moon?s diameter to the left (east) of Betelgeuse and is just visible to the naked eye.
A Brown Dwarf type star is only a fraction of the mass of the sun, in fact, it can only be up to 80 times the mass of the planet Jupiter.  Whereas the Sun is over a thousand times the mass of Jupiter. The light we see from a Brown Dwarf, is by the heat generated by gravitational pressure and gravitational pressure alone.  That is why it is only a faint object.  In the Sun the gravitational pressure is so great that nuclear fusion takes place and the heat generated is so much hotter that it shines very much brighter.

The orbit of the Brown Dwarf is what is called highly elliptical.  This can be likened to sitting down at one end of an oval (elliptical) table, with an egg cup in front of you, this represents the Sun, and the rim of the table the orbit of the Brown Dwarf.  You will readily appreciate that when the Brown Dwarf?s orbit is at the opposite end of the table, it is very much further away from the Sun and travelling slowly, but when it is on the rim of the table nearest the egg cup it is at its closest point to the Sun and travelling fast.

The time it takes for the Brown Dwarf to complete one orbit is around two million years and the reason we have not seen it before, is because it has been too far away.  lt will miss us by several hundred million miles and there is no chance of it causing any disturbance on Earth.  As for normal everyday activity it will be just another faint star in a myriad of stars orbiting in the celestial globe.
There is one possible thing it might do and that is right out on boundary of the Solar System.
Way out past the furthest planets, there is a region which is known as the Oort Cloud, and this is where there are tens of thousands of comet like objects.  If the gravitational pull of the Brown Dwarf should disturb the orbit of some of these comets, our forebears several generations hence ( 2 million years ) will be entertained to some spectacular cometary sights.

My tutors remarks on the above, ?You have given the important scientific detail in an appropriate manner.  However your account needs to be a little more dramatic to attract and hold the reader.*
Marks 18/25

What I did not put in the article because it was not supposed to alarm the public was that on working out the orbital period of the Brown Dwarf, it came to two million years, and if you remember, that was the length of time it would take for the disturbed comets in the Oort cloud to reach us. Which means of course, we are now due for a visit of several or several thousand comets.  You will have noticed that there are quite a few comets about and several of these are non-periodic.
Is this the beginning of a massive cometary display?  If it is, it could also be the beginning of the end of life on earth.
Conclusion, do all the things you have wanted to do because it?s later than you think.
Come to think of it, that?s not a bad thing to do anyway.  Me, well I?m storing the tubers for next years Dahlias; ?hope springs eternal from the human breast?