The prehistoric monument of Stonehenge has long been studied for its possible connections with ancient astronomy. The site is aligned in the direction of the sunrise of the summer solstice and the sunset of the winter solstice, and its latitude in respect to the Great Pyramid and Equator is precisely defined by the silver ratio. [1] Archaeoastronomers have made a range of further claims about the site's connection to astronomy, its meaning, and its use.
Stonehenge has an opening in the henge earthwork facing northeast, and suggestions that particular significance was placed by its builders on the solstice and equinox points have followed. For example, the summer solstice Sun rose close to the Heel Stone, and the Sun's first rays shone into the centre of the monument between the horseshoe arrangement. While it is possible that such an alignment could be coincidental, this astronomical orientation had been acknowledged since William Stukeley drew the site and first identified its axis along the midsummer sunrise in 1720. [2]
Stukeley noticed that the Heel Stone was not precisely aligned on the sunrise. The drifting of the position of the sunrise due to the change in the obliquity of the ecliptic since the monument's erection does not account for this imprecision. Recently, evidence has been found for a neighbour to the Heel Stone, no longer extant. The second stone may have instead been one side of a 'solar corridor' used to frame the sunrise. [3] [4]
Stukeley and the renowned astronomer Edmund Halley attempted what amounted to the first scientific attempt to date a prehistoric monument. Stukeley concluded the Stonehenge had been set up "by the use of a magnetic compass to lay out the works, the needle varying so much, at that time, from true north." He attempted to calculate the change in magnetic variation between the observed and theoretical (ideal) Stonehenge sunrise, which he imagined would relate to the date of construction. Their calculations returned three dates, the earliest of which, 460 BC, was accepted by Stukeley. That was incorrect, but this early exercise in dating is a landmark in field archaeology. [5]
Early efforts to date Stonehenge exploited changes in astronomical declinations and led to efforts such as H. Broome's 1864 theory that the monument was built in 977 BC, when the star Sirius would have risen over Stonehenge's Avenue. Sir Norman Lockyer proposed a date of 1680 BC based entirely on an incorrect sunrise azimuth for the Avenue, aligning it on a nearby Ordnance Survey trig point, a modern feature. Petrie preferred a later date of 730 AD. The relevant stones were leaning considerably during his survey, and it was not considered accurate.
An archaeoastronomy debate was triggered by the 1963 publication of Stonehenge Decoded, by Gerald Hawkins an American astronomer. Hawkins claimed to observe numerous alignments, both lunar and solar. He argued that Stonehenge could have been used to predict eclipses. Hawkins' book received wide publicity, in part because he used a computer in his calculations, then a novelty. Archaeologists were suspicious in the face of further contributions to the debate coming from British astronomer C. A. 'Steve' Newham and Sir Fred Hoyle, the famous Cambridge cosmologist, as well as by Alexander Thom, a retired professor of engineering, who had been studying stone circles for more than 20 years. Their theories have faced criticism in recent decades from Richard J. C. Atkinson and others who have suggested impracticalities in the 'Stone Age calculator' interpretation.
Gerald Hawkins' work on Stonehenge was first published in Nature in 1963 following analyses he had carried out using the Harvard-Smithsonian IBM computer. Hawkins found not one or two alignments but dozens. He had studied 165 significant features of the monument and used the computer to check every alignment between them against every rising and setting point for the Sun, Moon, planets, and bright stars in the positions they would have occupied in 1500 BCE. Thirteen solar and eleven lunar correlations were very precise in relation to the early features at the site but precision was less for later features of the monument. Hawkins also proposed a method for using the Aubrey holes to predict lunar eclipses by moving markers from hole to hole. In 1965 Hawkins and J.B. White wrote Stonehenge Decoded , which detailed his findings and proposed that the monument was a 'Neolithic computer'.
Atkinson replied with his article "Moonshine on Stonehenge" in Antiquity in 1966, pointing out that some of the pits which Hawkins had used for his sight lines were more likely to have been natural depressions, and that he had allowed a margin of error of up to 2 degrees in his alignments. Atkinson found that the probability of so many alignments being visible from 165 points to be close to 0.5 (or rather 50:50) rather that the "one in a million" possibility which Hawkins had claimed. That the Station Stones stood on top of the earlier Aubrey Holes meant that many of Hawkins' alignments between the two features were illusory. The same article by Atkinson contains further criticisms of the interpretation of Aubrey Holes as astronomical markers, and of Fred Hoyle's work.
A question exists over whether the English climate would have permitted accurate observation of astronomical events. Modern researchers were looking for alignments with phenomena they already knew existed; the prehistoric users of the site did not have this advantage.
In 1966, C. A. 'Steve' Newham described an alignment for the equinoxes by drawing a line between one of the Station Stones with a posthole next to the Heel Stone. He also identified a lunar alignment; the long sides of the rectangle created by the four station stones matched the Moon rise and moonset at the major standstill. Newham also suggested that the postholes near the entrance were used for observing the saros cycle. [6]
Two of the Station Stones are damaged and although their positions would create an approximate rectangle, their date and thus their relationship with the other features at the site is uncertain. Stonehenge's latitude ( 51° 10′ 44″ N ) is unusual in that only at this approximate latitude (within about 50 km) do the lunar and solar alignments mentioned above occur at right angles to one another. More than 50 km north or south of the latitude of Stonehenge, the station stones could not be set out as a rectangle.
Alexander Thom had been examining stone circles since the 1950s in search of astronomical alignments and the megalithic yard. It was not until 1973 that he turned his attention to Stonehenge. Thom chose to ignore alignments between features within the monument, considering them to be too close together to be reliable. He looked for landscape features that could have marked lunar and solar events. However, one of Thom's key sites – Peter's Mound – turned out to be a twentieth-century rubbish dump.
It has recently been proposed that a critical element of Stonehenge's early design is the diagonal of the Station Stones' rectangle. At an azimuth of 117.33° the diagonal uses a sighting from stone 93 to 91 to point not only toward the Bolbitine mouth of the Nile Delta, but also to the astronomical rising of Orion's belt only minutes before the Summer Solstice sunrise, ca 2600 BC. The ratio of the Station Stone rectangle's diagonal to its side ( 2.613 : 1) also mirrors the ratio of the eastern horizon segmented by the rising of the Summer Solstice sun, and is coincidently found in the diagonal of an octagon. [7]
Another interesting observation that has been published recently is the mean average diameter of the moon and the Earth might be drawn in the diameters of the stone and Earth circles at Stonehenge. Though this overlap could be coincidental, the same ratio between the size of the moon and the Earth is also seen in the size of the Earthwork at Stonehenge and the nearby circle at Durrington Walls. [8]
Although Stonehenge has become an increasingly popular destination during the summer solstice, with 20,000 people visiting in 2005, scholars have developed growing evidence that indicates prehistoric people visited the site only during the winter solstice. The only megalithic monuments in the British Isles to contain a clear, compelling solar alignment are Newgrange and Maeshowe, which both famously face the winter solstice sunrise.
The most recent evidence supporting the theory of winter visits includes bones and teeth from pigs which were slaughtered at nearby Durrington Walls, their age at death indicating that they were slaughtered either in December or January every year. Mike Parker Pearson of the University of Sheffield has said in 2005, "We have no evidence that anyone was in the landscape in summer." [9] Later on, in light of more recent research and findings, Mike Pearson reconsidered arguing that it is "reasonable to assume that they came to celebrate the midsummer solstice as well as the midwinter solstice". [10]
Archaeoastronomy is the interdisciplinary or multidisciplinary study of how people in the past "have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cultures". Clive Ruggles argues it is misleading to consider archaeoastronomy to be the study of ancient astronomy, as modern astronomy is a scientific discipline, while archaeoastronomy considers symbolically rich cultural interpretations of phenomena in the sky by other cultures. It is often twinned with ethnoastronomy, the anthropological study of skywatching in contemporary societies. Archaeoastronomy is also closely associated with historical astronomy, the use of historical records of heavenly events to answer astronomical problems and the history of astronomy, which uses written records to evaluate past astronomical practice.
Stonehenge is a prehistoric megalithic structure on Salisbury Plain in Wiltshire, England, two miles (3 km) west of Amesbury. It consists of an outer ring of vertical sarsen standing stones, each around 13 feet (4.0 m) high, seven feet (2.1 m) wide, and weighing around 25 tons, topped by connecting horizontal lintel stones. Inside is a ring of smaller bluestones. Inside these are free-standing trilithons, two bulkier vertical sarsens joined by one lintel. The whole monument, now ruinous, is aligned towards the sunrise on the summer solstice and sunset on the winter solstice. The stones are set within earthworks in the middle of the densest complex of Neolithic and Bronze Age monuments in England, including several hundred tumuli.
There are three related types of Neolithic earthwork that are all sometimes loosely called henges. The essential characteristic of all three is that they feature a ring-shaped bank and ditch, with the ditch inside the bank. Because the internal ditches would have served defensive purposes poorly, henges are not considered to have been defensive constructions. The three henge types are as follows, with the figure in brackets being the approximate diameter of the central flat area:
The Goseck Circle is a Neolithic structure in Goseck in the Burgenlandkreis district in Saxony-Anhalt, Germany.
Alexander Thom was a Scottish engineer most famous for his theory of the Megalithic yard, categorisation of stone circles and his studies of Stonehenge and other archaeological sites.
The Aubrey holes are a ring of 56 chalk pits at Stonehenge, named after seventeenth-century antiquarian John Aubrey. They date to the earliest phases of Stonehenge in the late fourth and early third millennium BC. Despite decades of argument and analysis, their purpose is still unknown, although an astronomical role has often been suggested.
Gerald Stanley Hawkins was a British-born American astronomer and author noted for his work in the field of archaeoastronomy. A professor and chair of the astronomy department at Boston University in the United States, he published in 1963 an analysis of Stonehenge in which he was the first to propose that it was an ancient astronomical observatory used to predict movements of the sun and moon, and that it was used as a computer. Archaeologists and other scholars have since demonstrated such sophisticated, complex planning and construction at other prehistoric earthwork sites, such as Cahokia in the United States.
CastleriggStone Circle is situated on a prominent hill to the east of Keswick, in the Lake District National Park, North West England. It is one of around 1,300 stone circles in the British Isles and Brittany, constructed as a part of a megalithic tradition that lasted from approximately 3,200 BC to 2500 BC, during the Late Neolithic and Early Bronze Ages.
Petroforms, also known as boulder outlines or boulder mosaics, are human-made shapes and patterns made by lining up large rocks on the open ground, often on quite level areas. Petroforms in North America were originally made by various Native American and First Nation tribes, who used various terms to describe them. Petroforms can also include a rock cairn or inukshuk, an upright monolith slab, a medicine wheel, a fire pit, a desert kite, sculpted boulders, or simply rocks lined up or stacked for various reasons. Old World petroforms include the Carnac stones and many other megalithic monuments.
The Station Stones are elements of the prehistoric monument of Stonehenge.
This is a list of Stonehenge replicas and derivatives that seeks to collect all the non-ephemeral examples together. The fame of the prehistoric monument of Stonehenge in England has led to many efforts to recreate it, using a variety of different materials, around the world. Some have been carefully built as astronomically aligned models whilst others have been examples of artistic expression or tourist attractions.
Manhattanhenge, also called the Manhattan Solstice, is an event during which the setting sun or the rising sun is aligned with the east–west streets of the main street grid of Manhattan, New York City. The astrophysicist Neil deGrasse Tyson claims to have coined the term, by analogy with Stonehenge. The sunsets and sunrises each align twice a year, on dates evenly spaced around the summer solstice and winter solstice. The sunset alignments occur around May 28 and July 13. The sunrise alignments occur around December 5 and January 8.
Carahunge, also known as Zorats Karer, Dik-Dik Karer, Tsits Karer and Karenish (Քարենիշ), is a prehistoric archaeological site near the town of Sisian in the Syunik Province of Armenia. It is also often referred to among international tourists as the "Armenian Stonehenge".
Stonehenge has been the subject of many theories about its origin, ranging from the academic worlds of archaeology to explanations from mythology and the paranormal.
The Q and R Holes are a series of concentric sockets which currently represent the earliest known evidence for a stone structure on the site of Stonehenge.
An astronomical complex or commemorative astronomical complex is a series of man-made structures with an astronomical purpose. It has been used when referring to a group of Megalithic structures that it is claimed show high precision astronomical alignments. For the study of Archaeoastronomy, such complexes of similar structures are required for adequate measurement and calculation to ensure that similar celestial sightlines were intended by the designers. These arrangements have also been known as observational, ceremonial or ritual complexes with importance for the study of prehistoric cultures.
The Cahokia Woodhenge was a series of large timber circles located roughly 850 metres (2,790 ft) to the west of Monks Mound at the Mississippian culture Cahokia archaeological site near Collinsville, Illinois, United States. They are thought to have been constructed between 900 and 1100 CE; with each one being larger and having more posts than its predecessor. The site was discovered as part of salvage archaeology in the early 1960s interstate highway construction boom, and one of the circles was reconstructed in the 1980s. The circle has been used to investigate archaeoastronomy at Cahokia. Annual equinox and solstice sunrise observation events are held at the site.
Warren Field is the location of a mesolithic calendar monument built about 8,000 BCE. It includes 12 pits believed to correlate with phases of the Moon and used as a lunisolar calendar. It is considered to be the oldest lunisolar calendar yet found. It is near Crathes Castle, in the Aberdeenshire region of Scotland, in the United Kingdom. It was originally discovered from the air as anomalous terrain by the Royal Commission on the Ancient and Historical Monuments of Scotland. It was first excavated in 2004.
An axial stone circle is a megalithic ring of stones of a particular design found in County Cork and County Kerry in southwest Ireland. Archaeologists have found it convenient to consider the axial five-stone circle and axial multiple-stone circle separately. The circle has an approximate axis of symmetry aligned in a generally northeast–southwest direction. The stone at the southwest side of the circle, rather than being an upright orthostat like all the rest, is a slab lying horizontally with its long thin edge along the circumference of the ring. Because it marks the axis of the circle it is called the axial stone.
| Structure and surroundings |  | |
|---|---|---|
| Replicas and derivatives | ||
| Studies | ||
| In culture | ||
| Concepts | ||
