Stonehenge: Some Myths Dispelled. Stonehenge is one of the best-known ancient sites on Earth, but there are lots of misunderstandings associated with it. Here are some of them, with corrections: Myth: Stonehenge is unique. Fact: this is true in the restricted sense that it is the biggest and perhaps the most complex of the stone circles, but there are literally hundreds of them known in Europe (and in Britain in particular). Some of them, like Avebury, cover a much wider area but are not so architecturally complex. Myth: Stonehenge was built by and was a religious site for the Druids. Fact: this notion was first introduced in the 1700s by an archaeologist named Stukely, a man who became obsessed with Druidism and in fact fancied himself a latter-day Druid. In fact, -- a subject I will return to in the more general context of determining the age of the Earth and the Solar System -- has shown that the first parts of Stonehenge were built about two thousand years before the Druids were around -- that is, about 4000 years ago. The whole site has various elements which were built, added to, changed, and rebuilt over a period of about 1500 years. Myth: Stonehenge could not have been built by the primitive people of the time. Fact: it is certainly true that the enormous sarsens (standing stones) and bluestones, weighing tens of tons, were transported from a considerable distance, which sounds daunting. But experiments with keen volunteers (first with some Oxford undergraduates, as I understand the story, and then later in a real-life experiment which I have on a video which you are welcome to borrow) have shown that this could readily be done by muscle-power (ropes and rollers) alone, even by moderately small groups of people. Moreover, there are simple ways to raise a heavy stone to a vertical position. (The stones never need to be lifted completely off the ground like a Lego block.) These aspects too have been experimented with by volunteers (and also in the study of the head-shaped stones on Easter Island, etc.). No need to invoke astronauts! Myth: this was a site of bloodthirsty human sacrifice. Fact: there is absolutely no evidence for this.

The Astronomical Significance.

There is undeniably some significance to the fact that when one stands at the centre of Stonehenge and looks out over the so-called heelstone (see page 60 of your text) one is looking in the direction of sunrise on the longest day of the year (June 21, Midsummer's Day). This marks the farthest northern sunrise point reached by the sun during the year. We can only speculate whether this was a cause of great religious celebration, or instead a more prosaic harvest (or planting) festival. But the alignment is surely not just an accident. On the other hand, some astronomers and archaeologists have made some really extraodinary claims (see the book `Stonehenge Decoded' by Gerald Hawkins, for instance). Basically they have looked at many possible alignments of one stone with another to see if they point in some important direction, such as to the point on the horizon where Sirius is seen to rise. The problem here is that there are many stones and thus very many possible lines of sight, many of which are bound (by coincidence) to point in an "astronomically interesting" direction. As an extreme example of over-interpretation, consider a suggestion about the use of the so-called Aubrey holes, a ring of 56 holes surrounding Stonehenge. (This suggestion does not come from Gerald Hawkins, by the way.) It so happens that eclipses happen in cycles of about 56 years, a phenomenon known as the Saros. Thus in May 1994 we had a nice eclipse of the sun here in Kingston; 56 years from now, we will see another one very much like it. This could have been known to the ancient Britons. (Certainly other ancient civilizations, such as the Mesopotamians, knew of this regularity, so oral traditions and record-keeping were at least that sophisticated in some places many centuries ago.) It is possible to show, in very contrived fashion, that the Aubrey holes could have been used as an eclipse predictor. The recipe sounds rather complex -- something like this: every day, move a stick from one hole to the next, while at the same time you move another stick in a different direction, skipping every third hole, ...etc etc. To my ears, this sounds rather unlikely; and indeed there is pretty good evidence that this was not the purpose of the Aubrey holes. Recent study has shown that the 56 holes were built long before the rest of Stonehenge, and it is very unlikely that something so complex would have been built first and then the simpler parts (like the aligned heelstone and so forth) added on later. For all we know, the Aubrey holes might simply be something like the locations of the campfires used when the 56 tribes of Wessex got together once a year for a festival. (I have made up that 'explanation', but my point is that we simply do not know for certain. We can only speculate.) Meanwhile, of course, Stonehenge retains an amazing appeal for people. As one who has visited it, I can testify that it has a very special atmosphere. And of course it has figured in a lot of literary and other contexts - for instance, it was the site on which `Tess of the d'Urbervilles' was arrested for murder in the Hardy novel of that name. I have many beautiful figures and modern representations, including examples of the indirect influences Stonehenge has had on our society in architectural and other ways. I would encourage you to borrow these figures from me -- or, better still, to visit the site itself, if you ever get the chance! Previous chapter:Next chapter

0: Physics 015: The Course Notes, Fall 2004 1: Opening Remarks: Setting the Scene. 2: The Science of Astronomy: 3: The Importance of Scale: A First Conservation Law. 4: The Dominance of Gravity. 5: Looking Up: 6: The Seasons: 7: The Spin of the Earth: Another Conservation Law. 8: The Earth: Shape, Size, and State of Rotation. 9: The Moon: Shape, Size, Nature. 10: The Relative Distances and Sizes of the Sun and Moon: 11: Further Considerations: Planets and Stars. 12: The Moving Earth: 13: Stellar Parallax: The Astronomical Chicken 14: Greek Cosmology: 15: Stonehenge: 16: The Pyramids: 17: Copernicus Suggests a Heliocentric Cosmology: 18: Tycho Brahe, the Master Observer: 19: Kepler the Mystic. 20: Galileo Provides the Proof: 21: Light: Introductory Remarks. 22: Light as a Wave: 23: Light as Particles. 24: Full Spectrum of Light: 25: Interpreting the Emitted Light: 26: Kirchhoff's Laws and Stellar Spectra. 27: Understanding Kirchhoff's Laws. 28: The Doppler Effect: 29: Astronomical Telescopes: 30: The Great Observatories: 31: Making the Most of Optical Astronomy: 32: Adaptive Optics: Beating the Sky. 33: Radio Astronomy: 34: Observing at Other Wavelengths: 35: Isaac Newton's Physics: 36: Newtonian Gravity Explains It All: 37: Weight: 38: The Success of Newtonian Gravity: 39: The Ultimate Failure of Newtonian Gravity: 40: Tsunamis and Tides: 41: The Organization of the Solar System: 42: Solar System Formation: 43: The Age of the Solar System: 44: Planetary Structure: The Earth. 45: Solar System Leftovers: 46: The Vulnerability of the Earth: 47: Venus: 48: Mars: 49: The Search for Martian Life: 50: Physics 015 - Parallel Readings.

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(Sunday, 25 February, 2018.)

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