Tuesday, May 31, 2011

Venus and the Morning Star Ceremony

By Ray Norris and Duane Hamacher

The planet Venus, named after the Roman goddess of beauty, is one of the brightest objects in the night sky and can even be seen during the day.  Because its orbit is closer to the sun than ours, it never steers far from the sun.  For example you will never see Venus and the sun on opposite sides of the sky.  It is commonly called the morning or evening star, as it occasionally appears as a bright “star” in the dawn or dusk skies.  In fact, it is so bright, that it is commonly mistaken for a UFO!  The brightness is caused by thick clouds that cover the planet (Figure 1), reflecting much of the incoming sunlight back into space.  Because of its brilliance and wandering nature (remember the word "planet" means “wandering star”), it is a universal feature in Aboriginal cultures across Australia.

Figure 1:   Venus from a passing space probe, showing the thick layers of dense carbon-dioxide atmosphere.  Image from Proportional Planets.

Yolngu people of Elcho Island in northeastern Arnhem Land in the Northern Territory (Figure 2) call the planet Venus "Banumbirr", and tell how she came across the sea from the east in the Dreaming, naming and creating animals and lands as she crossed the shoreline, and continued traveling westwards across the country, leaving as her legacy one of the ''songlines'' which are important in Aboriginal cultures.

Figure 2: Arnhem Land in the Northern Territory, showing Elcho Island.  Image from TravelNT

In an important and beautiful "Morning Star Ceremony", earthly Yolngu people communicate with their ancestors living on Baralku, the island of the dead, with the help of Banumbirr together with a "Morning Star Pole" (Figure 3). The ceremony starts at dusk and continues through the night, reaching a climax when Banumbirr rises a few hours before dawn. She is said to trail a faint rope behind her along which messages are sent, and which prevents her from ever moving away from the Sun. This faint line in the sky is probably zodiacal light, which is caused by extraterrestrial dust in the plane of the solar system. Although difficult to see for most of us in our polluted skies, it is easily visible in the clear dark skies and low latitude of Arnhem Land.

Figure 3: A morning star pole, made by Yolngu artist Richard Garrawurra, from Elcho Island. The tuft of Magpie-goose feathers at the top represents Banumbirr, and also represents a water lily. The patterns are traditional clan designs. The other tufts of feathers on pandanus strings represent other stars, and other clans.  Image from our website.

The Morning Star ceremony tells us two important things. One 
is that Yolngu people had already observed that Venus never strays far from the Sun, which they explain in terms of the rope binding the two bodies together - a bond that Isaac Newton called "gravity". The other is that the Morning-Star ceremony has to be planned well in advance, since Venus rises a few hours before dawn only at certain times of the year, which vary from year to year.  So the Yolngu people also track the complex motion of Venus well enough to predict when to hold the Morning Star Ceremony.

View a video regarding Morning Star Stories featuring a Marrangu song and dance from Central Arnhem Land:

We respectfully acknowledge the Yolngu people and other Aboriginal nations of Arnhem Land.

Tuesday, May 24, 2011

Supernovae and "Guest Stars"

Exceptionally massive stars live fast and die young.  Their enormous furnaces fuse matter at a fantastically high rate, giving them relatively young lives (astronomically speaking).  Our sun will maintain a fairly "average" life-span of 10 billion years before going through its death throes as a red giant, eventually expanding and puffing its outer layers into space as the central core slowly fades away.  However, stars with several times the mass of our sun will live short lives, some as little as 10 million years (a thousand times younger than our sun).  However, their lives will not end in a puff, but with a cataclysmic explosion.  This event, called a supernova, will release a tremendous amount of energy, making the star brighter than the entire galaxy for a brief time period before it fades over the course of weeks to months, leaving a shell of debris that expands into interstellar space, known as a supernova-remnant (see Figure 1).  These events are fairly rare, with only one occurring every 50 years in our galaxy (with a stellar population of over 200 billion).

Figure 1: The Crab Nebulae, a remnant shell of the 1054 AD supernova in the constellation Taurus.

From the vantage point of earth, a few of these events have been visible to the naked eye during human history and it is one of the proverbial 'Holy Grails' of Cultural Astronomy to find a conclusive account of one.  The 1054 supernova that produced the above nebula was witnessed and recorded by Chinese and Arab astronomers, although many other proposed, and subsequently discredited, accounts of this event have been promoted.  It has been suggested that Native Americans had recorded this event in rock paintings in Chaco Canyon, New Mexico, although there is no hard evidence that the painting represents this event.

Figure 2: A pictogram at Chaco Canyon, New Mexico that some researchers speculate represents the 1054 supernova.

In Australia, we are carefully searching for accounts of supernovae in oral traditions and artistic forms.  Not surprisingly, this is an extremely difficult task, as not only do tens-of-thousands of oral traditions exist, but many are fairly ambiguous in their description, making a direct link to particular events substantially problematic.  David Frew and myself were able to show, in 2010, that the Great Eruption of Eta Carinae (supernova-impostor event) was recorded by the Boorong clan of the Wergaia language group in northwestern Victoria in 1843.  However, there are some accounts that seem to indicate the arrival of "guest stars".

One story that may describe a supernovae was published in 1973, entitled "Fisherman Brothers".  This is a story of two brothers (Nuruguya-mirri and Napiranbiru) that became stars.  The brothers were fishing in a canoe when a storm hit, capsizing their boat.  The elder brother was stronger and helped his younger brother reach the shore, giving his life in return.  To honour the courage of the older brother, the community held a ceremony and a bright new star shone in the sky.  The two brothers are now two bright stars close together in the bank of the sky-river (Milky Way, called Milnguya).  

The story claims that we can still see the two bright stars and a faint star today.  While the names of the stars represented by the brothers are not given, it is possible that they are the pointers (Alpha and Beta Centauri), as they are the brightest and most obvious stars in the Milky Way.  If this is the case, the “bright new star” may be the SN 185 (Figure 3), which occurred close to Alpha Centauri and was visible for eight months in 185 CE, reaching a peak visual magnitude of 3.0 to 4.0.  This SN was recorded by Chinese astronomers and may have been recorded in Roman literature.  However, the star is now invisible to the naked eye and this supernova would not have been particularly bright to the naked eye.  However, other bright pairs of stars in the Milky Way are prominent in Aboriginal traditions, such as Shaula and Lesath in Scorpius, leading to other possibilities.  Unfortunately, we could not say for any certainty if this even described a supernova, much less which one it was!

Figure 3: An X-Ray image of SN 185, which may be responsible for the "guest star" described in the "Fisherman Brothers" story.  Image from NASA.

A second story, entitled "The Beginning Island" that was recorded in the 1830s, describes the formation of Tasmania.  When the sun (Parnuen) and his lunar wife (Vena) came into being, they dropped seashells to the small island (Troweena, which became Tasmania).  Their first child (Moinee), a strong, shining baby was born on that day.  His parents placed him high above the icy lands to the south of the island, becoming the “Great South Star”.  The next day, the sun and Vena had another child (Dromerdene), which they placed in the sky midway between themselves and Moinee.  The next day, twins (Beegerer and Piminer) were born, who became Sirius and Betelgeuse.  Moinee was angry from his loneliness in the south, so his parents sent two spirits (Une, lightning and Bura, thunder) to live with him above the Great South Land.  At the time, icebergs floated around the island.  Sometimes, Vena would set over an iceberg.  One day, an iceberg melted and she sank, and is only visible now at night as the moon.  The sun, in his anger, melted all the icebergs and gave the island to his son, Moinee, who has watched over it since.

This story is fairly ambiguous and attempts at trying to identify the star are problematic: the 'Great Southern Star' may be a reference to an unknown SN, or it may represent a star from a time when the earth's precession would have moved the positions of the stars in such a way that one of the brighter stars in the sky would have been nearer to the south celestial pole.  For example, 6000 years ago, the bright star Achernar would have appeared close (within 8 degrees) to the south celestial pole (Figure 4).

Figure 4: Precession of the Equinox as seen from 10,000 BCE to 14,000 CE.  Approximately 6,000 years ago, the bright star Achernar was very close to the south celestial pole and may represent the "Bright South Star" described in "The Beginning Island" Dreaming.  Image from Wiki.

Over human history, approximately 12-13 supernovae have been visible: 8 of which have occurred in the last 100 years, with another 4 or 5 probable events and many more unconfirmed candidates.  While this list does not include novae or bright, non-supernovae variable stars, we expect to find accounts of at least some of these events in oral traditions... and the search continues.

Monday, May 16, 2011

The Historic "Great Comets"!

By Duane Hamacher

Notice to Aboriginal and TSI people: this blog contains the names of Indigenous people that have passed away.

Last week we discussed comets and how they were perceived by Aboriginal Australians in the past.  This week, we will talk about historic “Great Comets”.  Comets with orbits that take them close to the earth may appear to be very bright in the sky, some of which can even be seen during the day. These are commonly referred to as "Great Comets", and over the last 200 years, we have been visited by one of these comets about twice a decade, although we may go 10 years without seeing one, or we may have two in the same year, such as in 1910 and 1911 (see Table 1 for a complete list of Great Comets from 1800-2000).

Table 1: A list of "Great Comets" from 1800-2000.  Click on the image to zoom.

In the two hundred years between 1800 and 2000, about forty naked eye comets were visible (Table 1) from Australia, or on average one every five years.  So we could say that naked eye comets were not particularly rare, and this is reflected in the fact that some of the literature and ethnographic accounts relating to Aboriginal astronomy do not simply describe perceptions of comets but refer to particular historic comets, including the ‘Great Comets’ of 1843, 1861, 1901, 1910, 1927, and Comet Halley. In some cases, the comet is not identified by name, but is inferred from the description and date.

The Great Comet of 1843

The Great Comet of 1843 was a bright, sun-grazing comet visible in the Southern skies from late-February to mid-April. It was visible near the Sun (within 1°) and became brightest on 7 March. The comet, so frightening in its brilliance (see Figure 1), prompted Aboriginal people near Port Lincoln, South Australia to run and hide in caves.  The Ngarrindjeri of South Australia saw the comet as a harbinger of calamity, specifically to the white colonists. They believed the comet would destroy Adelaide then travel up the Murray causing havoc in its path:

“In March 1843, I had a little boy living with me [in Moorunde, SA] by his father's permission, whilst the old man went up the river with the other natives to hunt and fish. On the evening of the 2nd of March a large comet was visible to the westward, and became brighter and more distinct every succeeding night. On the 5th I had a visit from the father of the little boy who was living with me, to demand his son; he had come down the river post haste for that purpose, as soon as he saw the comet, which he assured me was the harbinger of all kinds of calamities, and more especially to the white people. It was to overthrow Adelaide, destroy all Europeans and their houses, and then taking a course up the Murray, and past the Rufus [the site of an Aboriginal massacre], do irreparable damage to whatever or whoever came in its way. It was sent, he said, by the northern natives, who were powerful sorcerers, and to revenge the confinement of one of the principal men of their tribe, who was then in Adelaide gaol, charged with assaulting a shepherd; and he urged me by all means to hurry off to town as quickly as I could, to procure the man's release, so that if possible the evil might be averted. No explanation gave him the least satisfaction, he was in such a state of apprehension and excitement, and he finally marched off with the little boy, saying, that although by no means safe even with him, yet he would be in less danger than if left with me.”

When the Great Comet of 1843 was seen in Victoria, it caused “… dreadful commotion and consternation…” among the communities. “Spokesmen [presumably Elders or medicine men] gesticulated and speechified far into the night …” in an attempt to rid the comet, but with no success. When their actions seemed in vain, they packed up camp in the middle of the night and moved to the other side of the river and remained huddled together until morning. They believed that the comet had been sent to them by the Aboriginal people near Ovens River in northern Victoria to cause harm. They left the area and did not return until the comet faded away. Aboriginal people near Kilmore (Victoria) said that the tail of this ‘grand comet’ consisted of spears thrown by Aboriginal people near Goulburn to one another.

Figure 1: The Great Comet of 1843 as seen from Tasmania (Van Diemen’s Land). 
Painting by Mary Morton Allport (1806–1895).

The Great Comet of 1861

After surviving the shipwreck of the Peruvian in the Great Barrier Reef in 1846, four members of the crew reached Cleveland Bay on the coast of Queensland near present-day Townsville. One of the survivors, James Morrill, lived among the local Aboriginal people for 17 years, publishing his journals in 1864. He notes how the Aboriginal people used the same word for comets and stars (nilgoolerburda) and explains that comets were believed to be the spirits of men killed far away returning home, making their way from the clouds to the horizon. He described seeing a comet during the previous dry season (June to November) and noted that the Aboriginal people thought it was “… one of the tribe who had been killed in war…”. Morrill does not give a date for this sighting, but does go on to say that he witnessed a nearly total solar eclipse about six years earlier. From 1846 to 1864, only two nearly total solar eclipses (where the Moon covered >80% of the Sun) were visible from this region: on 5 April 1856 (T = 17:05:31) and 18 September 1857 (T = 17:28:04, where T is the time of mid-eclipse), despite Morrill claiming that he only saw one eclipse during the time that he was living among the Aboriginal people. This gives a period of approximately five years between the eclipse and the comet sighting, revealing the best candidate is the Great Comet of 1861, which is depicted in Figure 2 as the Earth was about to pass through its tail. This comet was discovered by the Windsor-based Australian amateur astronomer, John Tebbutt, and from Australia was visible as a conspicuous naked eye object from mid-May through to near the end of June, during the dry season, which implies that Morrill’s account was recorded in 1862. This comet had a distinctive tail that at its best extended 42°, and the comet appeared brightly in the northern sky throughout June as the Earth approached its tail.  The Aboriginal people told Morrill the comet was a spirit coming down from the clouds onto the horizon.

Figure 2: Williams’ drawing of Comet Tebbutt made on 30 June 1861, just after the Earth passed through its tail. 
By this time it was a very conspicuous object but was only visible to Northern Hemisphere observers.

The Great Comet of 1901

While engaging in ethnographic fieldwork in Queensland from 1901 to 1908, anthropologist and Northern Protector of Aboriginals, Walter E. Roth, noted that the Tjungundji people near Mapoon (Marpuna) on the western coast of Cape York Peninsula saw a comet as a fire lit by two old women. This was probably a reference to the recent Great Comet of 1901, which was visible exclusively in the Southern skies from mid-April to late-May and displayed distinctive, bright twin tails (Figure 3). In early May, when it reached peak brightness, the comet transversed the boundary between Taurus and Eridanus. The head of the comet, of magnitude 0 on 3 May and +2 on 6 May, would have appeared in the western evening skies near the horizon with the twin tails, comprising a 30° straight tail and a 10° curved tail, pointing upwards towards the star Sirius. By 12 May, the longer tail extended to the star d Leporis. At this time, the comet would have looked very much like two smoke columns diverging from a single point on the horizon. The comet remained visible until 23 May with the tails increasing in length to 45° and 15°, respectively. 

The Kaitish of the Northern Territory believed a comet was a bundle of spears belonging to a star endowed with a very strong magic. The people feared these spears would be thrown to Earth, killing many. It was believed by some that powerful members of the community could control natural events.  To avert the evil of the comet, a young, celebrated medicine man named Ilpailurkna was visiting the area from the neighboring Unmatjera clan. Each night he would project his magic stones towards the comet. As the comet faded away, its evil was overcome and the people were very grateful that Ilpailurkna had saved them. In the eyes of the community, had Ilpailurkna not driven the comet away, it would have fallen to Earth as a bundle of spears and everyone would have been killed.

Figure 3: Photograph of the Great Comet of 1901 with bright twin tails.
Taken at the Royal Observatory, Cape of Good Hope, South Africa.

The Great Comet of 1910

In 1910, the world awaited the return of the famous Comet Halley in May. However, the unexpected arrival of a bright comet in mid-January created much fear and awe.  Deemed the Great Daylight Comet of 1910 (Figure 4), it was bright enough to be seen during the day and at its peak, was brighter than Venus. It began to fade away in early February, followed a few months later by the arrival of the fainter, but still significant, Comet Halley. When Comet Halley returned in 1986, many of the older people around the world who recalled seeing it in 1910 had clearly described the Great Daylight Comet of 1910 and not Halley.

For example, in 1985, a Jiwarli man named Jack Butler from the Henry River in Western Australia, told of a “… star with a tail in the east …” he saw early in the year 1910 as a child.  The comet caused fear among the elder men who “… questioned what it was.” When the comet faded away the men were confused and wondered where it had gone. According to Butler, the object he saw in 1910 was Comet Halley. However, the Great Daylight Comet of 1910 was prominent in the morning twilight, consistent with the “… star with a tail in the east …” visible early in the year. Therefore, it is probable that Butler was describing the Great Daylight Comet of 1910 rather than Comet Halley.

Figure 4: The Great Daylight Comet of 1910 appeared just four months before Comet Halley but was
brighter than Venus at its peak (image rotated clockwise by 90°). Photograph from Lowell Observatory.

The Great Comet of 1927

Paddy Roe, a Nyigina elder, told of the appearance of a comet in the early twentieth century by an Aboriginal community on the Roebuck Plains west of Broome, Western Australia. The comet, which he described as “... a star with a tail ...”, was seen as a bad omen. However, after nothing bad happened the community held a celebratory corroboree.  Roe states that the comet was first seen during the “... new moon when the moon was a crescent...” (this refers to the time after a new Moon when the Moon appears as a thin crescent). These accounts date to the period “between the Wars”, presumably referring to World Wars I and II (between 1918 and 1939). The best candidate is the Great Comet of 1927 (Figure 5), discovered on 4 December 1927 by the Australian amateur astronomer John Francis Skjellerup when it was a third magnitude object with a 1° tail (although others claimed to have discovered it on 28 November 1927). The comet, first detected in the Southern Hemisphere, was visible primarily during the day and early evening. By the time it was visible at night, it faded rapidly. Since the comet was near the solar disc but could still be seen during the day, the sighting of Comet Skjellerup-Maristany is consistent with being seen at the time of a new Moon (the day it was claimed to have first been discovered, 28 November 1927, was just after new Moon), although this identification is uncertain.

Figure 5: Drawing of Comet Skjellerup-Maristany by R.A. McIntosh on 5 December 1927 (Orchiston Collection).

Although nearly all of the descriptions here are second-hand Western accounts, these accounts provide an important historical record of Great Comets from an Aboriginal perspective. We see that comets are frequently associated with spears due to the comet’s appearance resembling a bundle of spears, and that perceptions of comets amongst Aboriginal societies were usually associated with fear, death, omens, malevolent spirits, and evil magic, due to their awe inspiring and relatively unexpected nature, consistent with many cultures around the world.

Tuesday, May 10, 2011

Comets, Comets, Comets!

About once every five years or so, our skies are graced by a brilliant visitor, stretching across the sky like a "fuzzy star". These are comets - "dirty-snowballs" that become visible to us as they approach the sun. Comets are like icy asteroids... they are composed primarily of relatively low-density ice and dust. Most comets can be found in the spherical shell of debris in the outer solar system called the Oort Cloud and in a belt of debris beyond the orbit of Neptune, called the Kuiper Belt.  Astronomers believe that up to one trillion (that's a million-million) comets populate the Oort cloud, which extends up to one light year from the sun... nearly a quarter of the distance to the nearest star system (Alpha Centauri). In deep space, a comet looks much like an asteroid - there's no tail and it's not particularly bright. But if a nearby star or massive object passes close by our solar system, its gravity can knock the comet from its slow orbit and send it reeling towards the sun.  As it gets closer and closer, the ever-increasing intensity of the solar wind begins to vaporise the icy dust on the surface of the comet, which trails behind the comet. This is the tail of the comet and its most recognisable feature (Figure 1). The tail can stretch for millions of miles, littering the solar system with trails of debris, called meteoroid streams, which are the source of annual meteor showers as the earth passes through these dirty stretches of our cosmic neighborhood.

Figure 1: Comet Hyakutake: Great Comet of 1996.
Image courtesy of NASA.

Contrary to popular belief, the tail always points away from the sun, even as it moves away (because the solar wind always radiates from the sun). Some comets originate in the solar system closer to the sun and have rather short periods, which can be seen in the skies at regular intervals. The most famous of these periodic comets is Comet Halley, which appears in our skies every 75-76 years. As time progresses, these comets become lose more and more debris, shrinking smaller and smaller until the solar wind completely vaporises them. Other comets are either ejected back into deep space or fall to their deaths directly into the sun. 

Throughout history, comets have been seen with fear and fascination, frequently attributed to the world of celestial beings or as omens of death and destruction. When Westerners began studying Aboriginal communities in the early 1800s, they noted that the Aboriginal people viewed extraordinary or unusual natural events with great dread. The unexpected arrival of a bright comet often triggered fear and were associated with death, spirits, or omens – a view held by various cultures around the world. Such views include those of the Tanganekald of South Australia who perceived comets as omens of sickness and death, the Mycoolon of Queensland who greeted comets with fear, the Kaurna of Adelaide who believed that the sun father, called Teendo Yerle, had a pair of evil celestial sisters who were “long” and probably represented comets, and the Euahlayi of New South Wales saw comets as evil spirits that drank the rain-clouds causing drought, with the cometary tail representing a large thirsty family that drew the river into the clouds. The Moporr clan of Victoria described a comet as Puurt Kuurnuuk - a great spirit, while the Gundidjmara of Victoria saw a comet as an omen that lots of people will die.

Aboriginal people in the Talbot District of Victoria likened comets (called “Koonk cutrine too”) to smoke, where “too” means “to smoke”. This is similar to a report from Cape York Peninsula, where an Aboriginal community saw a comet as the smoke of a campfire.  Similarly, the Aboriginal people of Bentinck Island in the Gulf of Carpentaria called a comet burwaduwuru, which means "testicle with smoke".  A common view among Aboriginal communities of the Central Desert links comets to spears.  A Pitjantjatjara man named Peter Kunari described comets as the manifestation of a being named Wurluru who lived in the sky and carried spears that he occasionally threw across the heavens (a possible reference to meteors?). A similar association is shared by the Kaitish.  The Rainbow Serpent, a much-feared evil spirit found in the Dreamings of many Aboriginal groups, was sometimes associated with comets. Some speculate that the origins of the Rainbow Serpent lay in transits of Halley’s comet, which was seen every 76 years, reinforcing stories handed down by Kuku-Yalanji law-carriers and custodians of the Bloomfield River, Queensland.

In 1899, Spencer & Gillen described a form of evil magic called Arungquilta, which involved meteors and produced comets and was used to punish unfaithful wives in Arunta communities. If a woman ran away from her husband, he would summon men from his group and a medicine man to perform a ceremony intended to punish her. In the ceremony, a pictogram of the woman was drawn in the dirt in a secluded area while the men chanted a particular song. A piece of bark, representing the woman's spirit, was impaled with a series of small spears endowed with Arungquilta and flung into the direction of where they believed the woman to be, which would appear in the sky as a comet (bundle of spears). The Arungquilta would find the woman and deprive her of her fat. After the emaciated woman died, her spirit appeared in the sky as a meteor.  In 1907, Carl Strehlow cited a nearly identical ceremony. However, in Strehlow’s account, the man felt pity for his wife and decided to revive her by rubbing fat into her body. As she healed, the comet faded from view. In some Arrernte and Luritja communities, comets are spears thrown by an ancestral hero to make his wife obedient to him. To some Arrernte clans, a comet was also a sign that a person in a neighbouring community had died, usually because of infidelity, and pointed to the direction of the deceased.  A similar description is given about the Karadjeri of coastal Western Australia, but is instead attributed to meteors. Given the two accounts by Spencer and Gillen of the same ceremony, it is possible they are confusing comets with meteors.

Table 1: Aboriginal words for comets from across Australia. Click on the image to zoom.

Next week: Historic Comets in Aboriginal Astronomy

For more information (click on link for PDF of paper):

Hamacher, D.W. and Norris, R.P. (2011). Comets in Australian Aboriginal Astronomy. Journal of Astronomical History & Heritage, Vol. 14, No.1, pp. 31-40.

See also:  Comets Triggered Aboriginal Tales of Doom, by Stuart Gary, ABC Science (18 October 2010)

Monday, May 2, 2011

"Bridging the Gap" through Australian Cultural Astronomy: Part II

by Duane Hamacher and Ray Norris

We continue our discussion from last week...

Dynamics of the Earth-Moon-Sun System

In most Aboriginal cultures, the moon is male and the sun is female (e.g. Haynes, 2000; Johnson, 1998; Fredrick, 2008; Norris & Hamacher, 2009), although this is not universal (e.g. Meyer, 1846:11-12). Some of the accounts describe the sun-woman as an aggressive lover that chases the moon-man, who avoids her advances by zig-zagging across his path in the sky. This is an explanation of how the relative positions of the sun and moon change throughout the lunar month, where the moon can appear to the north, south, or in the same line as the sun. The Yolngu have a tradition that on rare occasions, the sun-woman (Walu) manages to capture the moon-man (Ngalindi) and consummates their relationship before he manages to escape, explaining a solar eclipse (Warner, 1937:538). A similar Dreaming from the Euahlayi of New South Wales says the sun-woman (Yhi) eclipsed the moon-man (Bahloo) in a jealous rage because he constantly avoided her advances. Bahloo is saved by the intervention of celestial spirits (Parker, 1905:139-140; Reed, 1965:130). A sexual encounter between the sun and moon as the cause of a solar eclipse is also found among the Wirangu of South Australia (Bates, 1944:211). Other Aboriginal groups deduced that something covered the sun during an eclipse, although it was not always identified with the moon (see Hamacher & Norris, 2011c).

Many oral traditions explain lunar phases in a cultural context. For example, the full moon is a fat, lazy man called Ngalindi to the Yolngu of Arnhem Land. His wives punish his laziness by chopping off bits of him with their axes, causing the waning moon. He manages to escape by climbing a tall tree to follow the Sun, but is mortally wounded, and dies. After remaining dead for three days (new moon), he rises again, growing fat and round (waxing moon), until his wives attack him again in a cycle that repeats to this day (Wells, 1964; Hulley, 1996). To coastal communities, the relationship between lunar phases and tides is well known. According to the Yolngu and the Anindilyakwa (Mountford, 1956), when the tides are high, the water fills the moon as it rises at dusk (full moon). As the tides drop, the moon empties (crescent) until the moon is high in the sky during dusk or dawn, at which time the tides fall and the moon runs out of water (first and last quarter). The moon begins to fill again when it rises at dawn (new moon).

These accounts show that Aboriginal people paid careful attention to the motions of the sun and moon, explaining the mechanics of an eclipse and the relationship between lunar phases and ocean tides.

Astronomical Measurements

The goal of this study is to determine whether Aboriginal people made astronomical observations and measurements. Here, we discuss two examples from the archaeological record. Wurdi Youang is an egg-shaped stone arrangement in Victoria, which was built by the Wathaurung people before European settlement. The stone arrangement is about 50 m in diameter with the major axis lying almost exactly East-West. At its Western apex are three prominent waist-high stones. Morieson (2003) pointed out that outlying stones to the West of the circle, as viewed from these three stones, indicate the setting positions of the sun at the equinoxes and solstices. Norris et al (2011) have confirmed these alignments and have also shown that the straight sides of the circle also indicate the solstices and the three stones as viewed from the Eastern apex, define the setting sun at equinox (Figure 1). This arrangement, if intended for this purpose, would have required careful observations of the sun throughout the year. The age and exact purpose of this arrangement are unknown, but the two independent lines of evidence for solar indications support an astronomical relationship.  Read more here.

Figure 1: The Wurdi Youang stone arrangement in Victoria.  The stone arrangement aligns with the solstices and equinox.  Image taken from the Australian Aboriginal Astronomy Project website.

Aboriginal stone arrangements in New South Wales have a variety of uses, including ceremonial and practical (e.g. McBryde, 1974; Bowdler, 1983; Attenbrow, 2002). We present preliminary results of a cardinal alignment survey of stone arrangements in New South Wales. We survey stone rows, pairs of stone circles/cairns (where the azimuth is measured from the centre of each circle or cairn), or single stone circles with an entrance and exit (Figure 2). 660 archaeological site cards were obtained from NSW Heritage, of which some contain a detailed archaeological survey. We set selection criteria for determining the azimuth of these arrangements, using the site cards alone as an initial test.  We then measured the azimuths (labeling North as 0 deg, East as 90 deg, etc.) of each arrangement using these predetermined criteria, being careful not to bias the selection in favour of cardinal points. Of the 660 site cards, we rejected 600 as either being ambiguous, having insufficient data, or being off-limits for cultural reasons. From the 60 remaining sites, we obtained 134 orientations, although the site cards did not always specify whether the orientation was true or magnetic North. However a preliminary analysis of the site card data shows (Figure 3) a clear, statistically unambiguous preference toward cardinal directions.

Figure 2: Three examples of stone arrangements with cardinal alignments, noting the site card number from the NSW Heritage database.

Figure 3:  A histogram of 134 azimuths in 5-degree bins, categorised into 97 stone rows (grey) and 37 stone circles (black). The histogram shows that stone rows are significantly more likely to be aligned to cardinal directions, either North-South (0 deg) or East-West (90 deg) than other directions. Stone circles, on the other hand, show a preference for North-South but not East-West.

Specifically, a Monte Carlo simulation has shown that the probability of a peak as high as that at (0 degrees) in Fig. 4 arising by chance alone is about 1 in 50 million, and the joint probability of getting both that and the peak at (90 degrees) is about 4x10-12.  We conclude that this is not a chance occurrence, but that the stone rows are deliberately aligned on the cardinal points. We are therefore conducting a series of field surveys of all sites with azimuths near cardinal directions to measure the accuracy with which these rows are aligned.

A preference towards cardinal azimuths indicates that the cardinal points were well known. The determination of cardinal points requires careful measurements of the sun throughout the day and year, as the rising and setting position of the Sun and other bodies varies significantly through the year.

One technique to determine south is to observe the rotation of the Southern Cross over the course of a winter's night, marking the position on the horizon vertically below its extreme easterly and westerly positions, then marking the half-way point between them. Similarly, East and West may be found by marking the extremes of the rising or setting sun's locations on the horizon over the year, then marking the halfway point between Thus the very existence of a significant number of structures aligned to the cardinal points implies a degree of planning, observation, and measurement that seem to be absent from most anthropological accounts of Aboriginal cultures. While any one structure might be aligned to the cardinal points purely by chance, we have shown that the probability of such a large number doing so is negligible.


We have given examples of how Aboriginal people made use of celestial phenomena for calendric, navigational, and cultural purposes and showed that Aboriginal people were careful observers of the night sky.  We have presented evidence that Aboriginal Australians noted the changing brightness of particular stars, deduced the complex motions of the sun and moon. Even more significantly, we have shown that Aboriginal Australians also oriented stone arrangements to cardinal directions and astronomical phenomena, such as the solstices and equinox. This shows that Aboriginal Australians made careful observations and measurements of celestial bodies and positions, casting a new light on our understanding of the development of Aboriginal culture.


This work is dedicated to the hundreds of thousands of Indigenous Australians who lost their lives, land, and culture after the British colonisation of Australia. Hamacher would like to thank the Department of Indigenous Studies at Macquarie University, the International Astronomical Union, the Astronomical Society of Australia, and the International Society of Archaeoastronomy & Astronomy in Culture for funding to attend Oxford IX. We also thank Dianne Johnson, John Morieson, John Clegg, Cilla Norris, Hugh Cairns, Bill Yidumduma Harney, Serena Fredrick, David Frew, Paul Curnow, Ros Haynes, NSW Heritage, and Kristina Everett.


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