Basic Astronomy (8/3/1984)

    With a title like ‘Basic Astronomy’ I suspect most of you are settling down to a fairly simple and straightforward talk, the contents of which you will all have heard before. Aah! he’ll go on about the Sun for x minutes, then go through the solar system, ending with Pluto. Then stellar evolution through to Quasars and Black Holes. All familiar, well worn material. It may be basic astronomy to us, but is not so for masses of people, even today, and certainly not in the past.

    Back to the beginning, the roots of civilisation and before, and we are presented with the difficult question as to when did people first speculate, as opposed to merely seeing  the Sun, Moon and Stars. Cave paintings of around 20,000 years ago show little of astronomical interest, and questions and ideas about who lit the stars at night and put them out in the morning were probably secondary to the source of the next meal. Not until groups and communities led more settled lives, perhaps after 10,000 years ago in some parts, did the dependence upon seasons for agricultural activity link with basic astronomy, especially the progress of the Sun and Moon.

   We have to wait some time for evidence to survive in written form but from 5000 years back there is ample hard evidence in the form of ‘temples’, burial customs, and structures such as Stonehenge and other stone or wood arrangements. Similar, earlier structures occur in the Middle East

    Although a select few would deduce the course and meaning of events, one can be sure that the community at large subscribed to the cost of erecting large monuments.

While primitive, the basic observations derived represent a milestone in human evolution, and there is no suggestion that any other creature has noted the heavens save in a seasonal manner for survival.

    In China, Egypt and the Middle East, from c.2000 BC., the development of written languages was another milestone, since astronomical observation as details could be recorded, stored, and shared by the written or drawn word among many people. For the ordinary person the seasons represented basic astronomy, but for an elite wonderful explanations were being put forward and accepted. The Chinese were already mapping the sky, the Egyptians had ideas ranging from the Sun god Ra stretching across the heavens, to a turtle supporting the Earth. The Arabs at this time were seriously studying the planets, and while much became common knowledge, as today, there were more questions to every answer.

    The ancient Greeks pushed scientific and mathematical to a level that would not be reached again for 1500 years. If you cast your minds back to school, to the maths and geometry lessons which you may remember with mixed feelings, most of it was based upon ancient Greek work. Euclid, Pythagoras, Ptolemy and Archimedes, pushed maths and physics to the limits of available materials and facilities.      

    Their measurement of the Earth’s circumference by having the Sun shining directly overhead in one place and measuring the deviation from the vertical in a place some hundreds of miles South depended upon accurate measurement of small angles, large distances, and longitudes. The ratio of Earth - Moon  and Earth - Sun distance which the Greeks tried to measure by recording the Sun-Earth-Moon angle when the Moon was exactly at first or last quarter was beyond the capabilities of their measuring equipment 

    Ptolemy’s famous solar system with Earth at the centre and all other stellar objects orbiting the Earth in sometimes very complex ‘epicycles’ became so established that it remained fundamental astronomy for 1500 years. There were many unanswered questions concerning the occasional unpredictable comet or nova or meteorite, as well as the not completely predictable planets. Consequently a great many legends and superstitions arose, especially when some unusual event in the sky coincided with major historical disturbances, giving rise to the art of astrology. And to the present day astrology has been the basic astronomy for many people.

   The Romans were strong on astrology, with astronomical beliefs taken from Greek ideas. Their main contribution was the introduction of the Caesarian Calender, based upon accurate astronomical observation, and this is basically still in use, with only the leap year refinement added at a later date.

   Although the Middle East maintained an interest, Britain and much of Europe entered  a so-called Dark Age and so far as astronomy was concerned this extended to about 1500. Basic astronomy and science was focused upon astrology, alchemy and, it seems, witchcraft.


   At the risk of getting a few boos and hisses from the more serious society members, I shall spend a few minutes on astrology, since this was for so long the layman’s view of astronomy. As everyone knows astrology is the ancient art of tying the mysteries of observable celestial objects with the even more mysterious puzzles as to why Earthbound people and events act and occur the way they do.

   Astrologers, past and present, perform a counselling service. In this an individual’s past history, problems, current and future events can be discussed by applying a birth date to various charts of celestial positions on that date.

   Everyone knows their own sign of the Zodiac, the classical style constellation in which the Sun occurs on their birthday. Twelve months of the year, twelve signs of the Zodiac. Each sign gives the person born under it certain character traits, although exceptions may be explained away by being born on the cusps, or near a transition of the Sun from one constellation to the next. The plot is thickened, as it were, by the infinitely variable positions of the Moon and planets.

    As well as one’s birth sign each person has 12 houses. Again, these are based on the classical Zodiacal constellations, so that Aries is the first house and Pisces is the twelfth house. The combination of planets and Moon in these constellations or houses for a particular date, time, and birth place, would be fairly unique. Within an hour or so a new constellation will have risen, another will have set, and by the next evening the Moon will have moved a lot, and all else to some extent.

   But in astrology objects don’t just rise and set, they ascend, reach mid-heaven and then descend. In ancient times there was the Sun, Moon,  and five planets out as far as Saturn, besides the occasional comet. Now all the planets, even Pluto, are said to contribute to personality and to life events, depending on their position at the date of birth. This precise timing of birth with the celestial positions is the basis for casting horoscopes. Another aspect, in more senses than one, is how, astrologically, the planets influence historical events. It relates to their angles to the Sun or to one another. Oppositions and conjunctions are well known but when planets are 60 degrees and 90 degrees apart we have so called trines and quadrants, all having astrological significance.                                                 

   As you see, astrology is a complex and specialised subject. It was not the preserve of ordinary folk but encompassed the wealthy, and kings and emperors who consulted astrologers before major decisions and battles. (Curiously, the Church seems to have had no particular views or influence on the matter).

   It has been said even during the 39-45 war astrology was used when all other means of forecasting the results of momentous decisions had been exhausted. Life is often puzzling in that seemingly insignificant moments can have far reaching effects, unperceived at the time, while major efforts to achieve something are dogged by unlikely  and unforseeable setbacks. It is not surprising that throughout the centuries       

people have turned to astrology in an attempt to find some pattern in life. I myself do not believe that the moment of birth or planetary positions can influence personal or general history, but cannot deny that some people appear to have an uncanny knack in prophecy.


   Back to astronomy, and the revival of science and art in late medieval Europe, when the names of Galileo, Kepler, Newton and others appear. After early struggles with the established Ptolemy ideas, the elements of modern astronomy arrived. Printing disseminated knowledge on a wide scale, sky charts were published, telescopes and timepieces were improved and eventually accurate maritime navigation was established. Optical instruments improved rapidly and though telescopes were expensive, the astronomical data available in books was not, and by 1900 most people had a reasonable understanding of the solar system. The development of radio astronomy, the construction of massive observatories, and now with the exploration of Space and its full publicity, we are at the threshold of a new astronomical age.

   I said I would not be discussing the astronomy of the Sun, planets, galaxies etc., but mentioned nothing about slides, so will finish this talk with a few well known but classic slides of those items! 


                                        Thank You.