Gerald Hawkins

Astronomer who 'decoded' Stonehenge

Gerald Stanley Hawkins, astronomer: born Great Yarmouth, Norfolk 20 April 1928; married first Dorothy Willacy-Barnes (two daughters; marriage dissolved), second 1979 Julia Dobson; died Woodville, Virginia 26 May 2003.

On this year's midsummer solstice morning, as usual, a great crowd - nearly 30,000 people - gathered at Stonehenge to watch the disc of the dawn sunrise exactly over the Heel Stone. This annual observation, if cloud or mist does not obscure, is seen to prove that the most famous of all prehistoric monuments is astronomically oriented.

A solar element in Stonehenge's geometry had been known for many decades, but to the English-born and American-based astronomer Gerald Hawkins is due the stronger proposition: Stonehenge was built as an astronomical observatory-cum- computer. Its many upright stones and other features were placed to capture alignments to a host of solar and lunar events, set so as to record or to observe the many points around the horizon where sun and moon rise or set on significant days. This idea, first set out by Hawkins in two Nature papers in 1963 and 1964, was then stated at book length in his Stonehenge Decoded (co-authored with John B. White, 1965). Ever since, the million people a year who go to Stonehenge know what was the ancient purpose of the place they see.

Hawkins's celebrated study prompted others to explore Stonehenge astronomy, and the wider field of "archaeo-astronomy" or "astro-archaeology" of which it would be part. By 1965 Hawkins himself had already worked out a broadly comparable astronomical scheme for prehistoric Callanish, the singular and complex array of standing stones in the Outer Hebrides which he called "a Scottish Stonehenge". (Perhaps it was in the Scottish rain he began his habit of wearing a deerstalker.)

He also studied astronomical aspects of Egyptian, Mayan and Aztec archaeology, moon markings in ancient cave art, and the enormous ground figures of Nasca in the Peruvian desert. Varied insights emerged there, but none so clear and compelling as his vision of Stonehenge, which swept the field.

For Stonehenge, the Cambridge astronomer Sir Fred Hoyle produced his own scheme of what was observed there and how eclipses could be predicted by manipulating features of it. By degrees, a profound problem of method emerged which to this day undermines, perhaps fatally, studies of prehistoric astronomy: the fact that a skilled and knowledgeable astronomer today, equipped with all elaborations of modern understanding, can devise a way to use Stonehenge as an observatory or calculator does not in itself prove that was its original use and purpose. Stonehenge, if you made the right observations or moved the stones about in the right way, could be used nowadays to predict the opening hours at Salisbury Museum, or of Sainsbury's in Swindon.

If one follows the evidence of ambiguous archaeological traces and of anthropological analogy, even the basic orientation of Stonehenge is falsely understood: the monument is not oriented north-east towards the midsummer sunrise but in the other direction, south-west towards the midwinter sunset - in the view of the present writer, an archaeologist unpersuaded by the more ambitious archaeo-astronomical schemes. The crowd ought to go on a December afternoon, not a June morning.

Born in Yarmouth, Gerald Hawkins studied mathematics and astronomy at Nottingham and Manchester universities, then emigrated to the United States. In a busy professional life there, he was long associated with the Smithsonian Institution, and its commitment to public education and outreach. He was founding professor of the astronomy department at Boston University, writer of notably clear and engaging books introducing varied aspects of astronomy, and pioneer of computer analysis.

One of his later research interests was again in southern England, the "crop circles" which from the late 1980s started to proliferate in cornfields near, especially, the ancient site of Avebury, the older twin to Stonehenge. While others persuaded themselves crop circles were made by UFOs, or by mysterious twisting vortices in the hot summer air, Hawkins thought them to be human-made. Studying their geometries, he found they conformed to numerical relationships expressing exact ratios distinctive of the major musical scale. Crop circles, it is now agreed, are made by people with planks and broom-handles and bits of rope who like making crop circles in fancy and elaborating shapes - but who know and care nothing of spatial geometries mathematically derived from musical harmonics.

Re-reading Stonehenge Decoded today, one is struck by how much it captures and expresses that optimistic attitude to technology so characteristic of its time, the early 1960s. As it enthusiastically told the story, the key work was done in 1961, not by Hawkins with pencil and paper, but by 40 seconds of machine time on the Harvard-Smithsonian IBM 740 computer, helped by its friend Oscar, the automatic plotting machine. Their human assistants fed in the data on punched cards, set the program running, and - astonished - then heard its astounding answer. Machine had spoken to machine, computer to computer, so that Stonehenge was decoded and enabled to speak to us through the translating intelligence of its fellow IBM, after an uncomprehending silence of 40 centuries when it had been an insoluble mystery.

But that mighty IBM 740, as Hawkins himself immediately reported, was already "as obsolete as the hand-crank telephone" when Stonehenge Decoded came out. A cheap mobile phone now has more computing power.

As technology forges ahead whilst respect for technology declines, it is not a coincidence that the other vision of Stonehenge and the one becoming more influential sees it once more as a sacred place of superhuman earth mysteries. It is a tribute to the ingenuity, imagination and persuasiveness of Gerald Hawkins (who died in May, stipulating that there should be no announcements or obituaries) that this more mysterious Stonehenge now sits alongside and secondary to his enduring perception of it as primarily an astronomical and scientific place.

Christopher Chippindale