The Star of Cabral

And your Southern Cross is our history: our traditions and our trust, «our yearning and our ambitions; he saw the unknown land and the discovered land

Olavo Bilac

Few countries have a flag as beautiful as Brazil’s. And few countries have a flag that is so loaded with symbolism. The national colours, which were already present on the flag of the independent country, represent the Brazilian nature: the green symbolises the vast forests found inland; the yellow, their mineral riches. The layout is unusual: floating over a green field is a yellow rhombus in which is inscribed a celestial sphere crossed by a white band.

The well-known Atlas of Franese shows the celestial sphere on the back of Atlas, the mythical giant condemned by Zeus to carry the weight of the world on his back. The sculpture dates back to the second century and presents the oldest known celestial globe, however it is most certainly copied from previous models. It reproduces the astronomy of Eudoxo and Hipparchus, with the classical constellations. The image of the sky is “inverted”, as it corresponds to an imaginary vision of the stars, seen from outside the celestial sphere. The Brazilian flag also shows an image of the celestial sphere seen from the outside, showing the southern sky as the Greeks imagined the gods could see the firmament.

The current Brazilian flag has a modern design yet it is the most recent link of a lengthy tradition. The first flag to have been raised in the lands of Vera Cruz was the banner of the Order of Christ, with its characteristic cross. This was followed by other royal flags, which reflected the political changes of the Portuguese metropolis until 1822, when D. Pedro proudly introduced the imperial flag of Brazil, with its arms over a yellow rhombus against a green background. In 1889, the implantation of the Republic led to the reformulation of this flag, with the imperial arms being replaced by a blue sphere, sown with stars and crossed by the white band, on which “Order and Progress” can be read. A few changes were made later, namely in relation to the stars so as to represent the Brazilian states, which in the meantime were subdivided and regrouped.

(click on the picture to see an enlarged version)
The artificers of the flag of the Republic of Brazil were positivists, followers of Auguste Comte. In no other country did this philosophical current have such political and cultural influence. The photographs show the Positivist Temple in Rio de Janeiro, where lessons in positivist catechism are announced. Due to the irony of history, an agnostic current was transformed into something rather similar to a religion.

The blue sphere, which represents the celestial sphere, was inherited from the Portuguese cult of the sphere of Manuel I, which symbolised the great journeys of marine exploration 1. However, it is a different celestial globe. The lettering on the white band synthesises a rationalist and positive motto of Auguste Comte: “love as a principle and order as a basis; progress as an end”. This was a famous motto at the time and a saying with which many republicans identified themselves. The band containing the lettering has been interpreted as symbolising the great Amazon River 2; however, just as with the band of the sphere of Manuel I, it appears in representation of the zodiac, the band of the celestial sphere through which the sun passes in its apparent annual movement.

The celestial symbolism is very important on the Brazilian flag. Its founders decided that the sphere would represent the sky over Rio de Janeiro at the hours of the morning on which the republic was proclaimed. The Brazilian law is precise: “The constellations which appear on the National Flag correspond to the aspect of the sky of the city of Rio de Janeiro, at 8 hours and 30 minutes on the 15th of November 1889” (Law no. 5.443, of 28 May 1968). The number of stars on the flag – 27 since 12 May 1992 – corresponds to the current 26 states of Brazil, in addition to the Federal District, which incorporates Brasilia.

The blue sphere contains three easily recognisable constellations – the Southern Cross, the Southern Triangle and the Scorpion. It should be noted, nonetheless, that their representation on the flag presents an inverted image of its appearance in the firmament. Following the tradition of the celestial globes, the sphere is represented as seen from the outside, from the infinite. We are “taken behind” the stars, seeing the imaginary celestial sphere in the same way as our forefathers imagined the gods could see it.

The stars are represented as having five points, as in the heraldic custom, and five different dimensions, in an attempt to symbolise the apparent brightness of the celestial stars, normally called magnitude. The ancients believed that all of the stars were fixed in the same crystalline sphere and at the same distance from the earth. They thought the difference in brightness was merely due to their size, to their magnitude. They classified the brightest stars as the biggest, which are the ones that can be seen immediately to the west. The second brightest were classified as being of secondary magnitude, and so on, up until the stars in sixth place, which could only just be seen. The Brazilian flag portrays stars of five different sizes, all of them visible to the naked eye from any point in the country. In general, an attempt was made to establish a correspondence between the stars and the states, as well as a correspondence that respected both the size of the territories and their geographical location. However, this parallelism is not always perfect, as can be expected.

Some of the stars have an illustrious history and their presence on the Brazilian flag is loaded with symbolism. The Spica star, in the constellation Virgo, is the only one that appears to the north of the white band. The presence of this constellation that takes up a significant part of the northern hemishpere, marks the territory north of the equator. This star, which in reality is situated south of the equator and south of the central line of the zodiac – the ecliptic – appears to be out of place to the north of the band, which consciously distorts its celestial position, but reveals the boreal presence of this large country. There are in fact very few countries of similar geographical dimension and among those that can rival Brazil in terms of area, no other country has territory that spreads over two hemispheres 3. The star belongs to the constellation of the goddess Demeter (Ceres to the Romans), goddess of agriculture habitually represented with an ear of grain, punctuated by the star with the same name. For the republicans, agriculture was a vital tool for development. However, the founders of the flag insisted above all on the meaning of this star in the history of science. The observation of the positioning of the Ear of grain is in fact connected to the discovery of the precession of the equinoxes by Hiparco (c. 180-125 B.C.), which was one of the major discoveries of astronomy. It is known today that the precession is a very slow continuous shift of the earths’ axis, which alters the position of the celestial poles and the intercession of the equator with the ecliptic. Owing to precession, the North celestial pole has been getting closer to the Pole Star. It is also owing to precession that the stars of the Southern Cross, visible in Alexandria at the time of Ptolemy (c. 90-168 A.D.), are no longer visible at this latitude.

Further below, the Canopo star appears, of the old Argo or Navis constellation, classified in modern times in the Carina (keel of a ship) constellation. It reminds us of the legend of the Argonauts, who undertook the journey to Colchis to steal the Golden Fleece, the fleece of the ram possessor of Reason. According to the creators of the flag, this star represents this journey of the Portuguese navigators, who reached South America in search of a modern Golden Fleece.

The star closest to the South Pole, the Sigma Octant, being the star around which all the others revolve, represents the Federal District, the political centre of the large Brazilian republic. The central stars correspond to the mythical Southern Cross asterism 4, which takes a prominent place and which, at the historical moment of the proclamation of the republic, was passing over the meridian of Rio de Janeiro.

According to some doctrinaires of the republican flag, the stars of the Southern Cross are the agnostic and modern counterparty of the Cross of Christ, transported on the ships of Pedro Álvares Cabral and of the Portuguese discoverers 5. To all, the Southern Cross is a link between the Portuguese and the Brazilians, united by the adventurous journeys of the fifteenth and sixteenth centuries.

The story of the discovery and appropriation of this celestial cross is a mythical story of astronomy and of navigation sciences. When the Portuguese started sailing down the coast of Africa, and especially when they overcame the simple coastal navigation and started following the major currents and Atlantic winds, they started making systematic use of celestial milestones in order to find out the latitude of the place in which they found themselves. At first, the Pole Star could be followed and its altitude measured – the angular altitude corresponds to the northern attitude of the place. As the navigators drew closer to the equator, the Pole Star started dipping into the horizon, making it difficult and then impossible to measure its height.

The drawing of the sky included in Mestre João’s letter, on the left, is the European representation of the oldest known southern sky. Prominence is given to the Southern Cross, above, and to the area of the pole, in the bottom right hand corner. The drawing on the right shows a modern map of the skies, with the stars that could correspond to those drawn by Mestre João drawn in red. The pole is marked with a cross.

According to Greek and Roman mythology, the Ursa Minor (or Little Bear), whose tail contains the Pole Star, and the Ursa Major (or Great Bear), which helps to locate it, had been banished to the Arctic by the goddess Juno, jealous of Jupiter’s relations with the nymph Callisto. The goddess condemned the nymph to take on the form of a bear and Zeus sent his son Arcas to go with her. Living in the Arctic, the two constellations were circumpolar to the classical Greek world and also to the latitude of Portugal, i.e. they were visible all night and at any time of the year 6. And thus the punishment imposed by Juno, which did not allow Callisto and Arcas any rest, was complied with.

On approaching the equator, the mariners reached skies unknown to the old astronomers, thus breaking the ancient spell. As our poet says:

I saw both Beares (the Little and the Great)
Despight of Juno in the Ocean set.”
(The Lusiads, V, 15)

When the Pole Star dipped into the sea, a celestial mark crucial for navigation was lost. The only measurement left for the Portuguese mariners was the altitude of the Sun. Although this measurement was easier to make, its application was more complex, as it required the recourse to declination tables of our star. The altitude of the midday sun did not only depend on the latitude but also on the day of the year. The tables made it possible to compensate these factors and thus calculate the latitude at which the travellers found themselves. However, it continued to be useful for the explorers to have a night-time measurement of the latitude and a cardinal pointer. They therefore looked for a star that could play the role at southern latitudes, which the Pole Star played in the northern hemisphere.

The search for a “South Pole Star”, i.e. a bright star that was located in the celestial South Pole or very close to it, was a quest that occupied the cosmographers and pilots of the fifteenth and sixteenth centuries. The Portuguese and the Spanish, and much later the English and the Dutch, all revealed this central concern. With time, it became apparent that such a star in the South Pole did not exist 7, contrary to what was imagined by many cosmographers who designed the boreal celestial hemisphere along the lines of the known southern hemisphere 8.

The mariners who started approaching the equator and crossing it towards the South scanned the sky carefully, trying to see which of the stars moved less throughout the night. Those that described shorter arcs with a smaller radius would be those that were closest to the pole. The desired star would be one that revealed no movement, with the entire firmament revolving around it. As is known, the longed-for guide of the travellers was not found for the simple reason that it does not exist. However, the pilots of the Portuguese ships discovered that the longest shaft of the Southern Cross points towards the pole. It was this asterism that became the guide of those that braved the seas south of the equator.

Even today in the literature on the history of constellations there are many erroneous references in search of the mythical South Pole star and only rarely is the historical truth respected, even among those who truly search for it. The most quoted reference must be, even today, “Star Names: Their Lore and Meaning”, by Richard Hinckley Allen 9. Here it is mentioned that some of the stars of the Southern Cross were observed in Alexandria by Ptolemy and were included by this astronomer in the Centaurus constellation which, according to the modern definition of constellations, borders on the Southern Cross. Allen’s reference is correct, although it is debatable which of the stars were really detected by the Alexandrian astronomer 10. Allen also refers that Dante must have known of the existence of these stars as in his Purgatory the poet writes:

Io mi volsi a man destra e posi mente
Al otro polo e vidi quatro stelle
No viste mai fuor che alla prima gente 11,
(Purgatory, I, 22–24)

This was an idea defended by Alexander von Humbolt who, in his Examen Criticum, insists that it was a reference to the stars of the Southern Cross. In the present-day, however, this idea has been abandoned, as Dante could not have known that these stars existed, admitting that the poet was referring to fictitious celestial bodies, which supposedly represented the four cardinal virtues 12.

Another common theory echoed by Richard H. Allen is that Américo Vespúcio was the first European to detect the stars of the Southern Cross and that he supposedly called it mandorla 13. In truth, as shown by Luciano Pereira da Silva 14, the stars to which Vespúcio was referring could not be those of the Southern Cross, as these are situated at approximately 30 degrees from the pole, while Vespúcio maintains that those of the so-called mandorla were a little more than 10 degrees from the pole.


In another well-known work 15, Lloyd Motz and Carol Nathanson, refer that António Pigafetta, the companion of Magellan, was the first to have used the term “cross”, in 1520, in order to refer to the stars of the Southern Cross, while Julius Staal, author of one of the most quoted works on the mythology of the skies, says that the acknowledgement of these stars as a separate constellation dates back to 1592 and that the French astronomer was the first to define its outline in 1679 16.

The historical truth, as it can be defined with the existing documents, was systematically restored from at least 1913 by Luciano Pereira da Silva 17 and was repeatedly reinforced by the most recent studies of Luís de Albuquerque and others 18. The international scientific literature 19 acknowledged these studies much later, yet it continues to be dumbfounding that so little be known about the truth 20.

The first written reference to the Southern cross and on which there is solid knowledge is one of the first documents to be written on what would become Brazilian soil, who knows perhaps even the first missive that originated on the soil of the future country. It is a letter from Mestre João, the royal physicist and surgeon who accompanied Pedro Álvares Cabral on his historical journey and who, between 28 April and 1 May 1500, wrote to king D. Manuel, explaining his astronomical research: “e aun esto dudoso que nõ se qual de aquellas dos mas baxas sea el polo antartyco, e estas estrellas principalmente las de la crus son grrandes, casy como las del carro [Ursa]” 21.

Here we have, therefore, the constellation of the Southern Cross referred to as cross, 20 years before Pigafetta used this name and months before Vespúcio searched, still confused, for the stars of the mandorla close to the pole. In his letter, Mestre João drew the brightest stars of this area of the sky with very reasonable precision, as witnessed by anyone who has ever tried to draw the relative positions of the stars freehand 22.

A little later, in 1514, even before Pigafetta had made reference to the constellation, Pilot João de Lisboa had written a complete Rule of the Southern Cross, in which he explained how this constellation could be used to determine the true southern pole and to correct the compass readings. In this document, João de Lisboa provides a celestial map in which he draws the Southern Cross with remarkable precision. And the pilot of D. Manuel reveals that he is merely describing studies carried out eight years before in Cochim, in partnership with Pêro Anes. In other words, according to the description of João de Lisboa, already in 1506 the Portuguese pilots focused their attention on a group of stars, which they called Southern Cross and of whose value to navigation they were already aware 23.

The discovery of the Southern Cross and the exploration of the southern skies is associated to the historical journey of Pedro Álvares Cabral and was written with heraldic stars on the modern flag of modern Brazil.


1- For information on the symbolism and history of the Brazilian flag, the following works can be consulted: Raimundo Olavo Coimbra, A Bandeira do Brasil: Raízes Históricas e Culturais, Rio de Janeiro, Fundação IBGE, 1972, Sebastião Ferrarini, Armas, Brasões e Símbolos Nacionais, Curitiba, Edições Curitiba, 1983, or Milton Fortuna Luz, Os Símbolos Nacionais, Brasília, Secretariado de Imprensa e Divulgação da Presidência da República, 1986.

2 - Cf. Coimbra, op. cit. secção 3.3.4.

3 - Teixeira Mendes, doctrinaire of the flag, states, however, that the territorial area in the northern hemisphere is represented by the inclusion of the Procyon star of Canis Minor, situated north of the equator yet south of the ecliptic, and that the displacement of the Ear of grain to the north of the band is due to aesthetic reasons (V. Coimbra, op. cit., secção Teixeira Mendes, however, forgot that both the states of Pará (represented by the Ear star) and of Amazonas (represented by the Procyon star) have territory in the northern hemisphere (idem,

4 – Five other countries include this constellation in their flags: New Zealand, since 1869, Australia, since 1901, Samoa, since 1949, and Papouasia-New Guinea, since 1971.

5 - To Teixeira Mendes, the catholic faith was a “medieval belief”, characteristic of the “poetic imagination of our grandfathers”. To José Feliciano, the flag replaced the Cross of Christ with “a celestial cross, without a doubt more elevated, more sublime and marvellous” Cf. Coimbra, op. cit. section 3.3.9.

6 – And continue to be so, although part of the area in modern times ascribed to the Ursa Major dips into the horizon.

7 – The star closest to the celestial south pole that is visible to the naked eye is the Sigma Octant, a star of fifth magnitude (5.45) only visible in good atmospheric conditions and therefore of little use to navigation.

8 - Alvise da Cadamosto (c. 1432–1483), Venetian navigator at the service of Infante D. Henrique, wrote in his description of his journey to the Gambia River in 1454: “as I can still see the North Pole Star, I cannot yet see the Pole Star of the South itself but the constellation I am looking for is the Plough [Ursa Major] of the South” (translated from A. Pannekoek, A History of Astronomy, New York, Dover, 1989, p. 185).

9 – Published in 1899 by G. E. Stechert with the title “Star-Names and Their Meaning” and reprinted by Dover, New York, in 1963.

10 - See Luciano Pereira da Silva, A Astronomia de Os Lusíadas, Lisbon, Junta de Investigações do Ultramar, 1972, pp. 189–213 e passim. This is a re-edition of the original work, included in the Revista da Universidade de Coimbra, volumes II to IV, 1913 to 1915.

11 – “I turned to my right and placed my mind / on the other pole, and there I saw four stars,/ seen only by the first people”, translation of Vasco Graça Moura, A Divina Comédia de Dante Alighieri, Venda Nova, Bertrand Editora, 1995, where the following footnote appears: “~The four stars correspond to the four cardinal virtues (Prudence, Justice, Strength and Moderation).»

12 - V. Pannekoek, op. cit. p. 186 e F. Anglelitti, «Sugli accenni danteschi, alle constellazioni ed al moto del cielo stellato da occidente in oriente, di un grado in cento anni», Rivista di Astronomia, Turim, VI, VII, 1912 e 1913.

13 - Literally, “almond”. Term used in Italian to describe the halos of the saints ascending to the skies.

14 - Op. cit., pp. 207-209.

15 - The Constellations, New York, Doubleday, 1988, p. 363.

16 - Julius D. W. Staal, The New Patterns in the Sky, Blacksburg, Virginia, McDonald and Woodward, 1988, p. 247.

17 - Op. cit.

18 - See, for example, Luís de Albuquerque, Navegação Astronómica (Astronomia Náutica), Lisbon, Comissão Nacional para a Comemoração dos Descobrimentos Portugueses, 1988, pp. 119-131. See also Abraão de Morais, «A astronomia no Brasil», in Mário Guimarães Ferri e Shozo Motoyama (editors), História das Ciências no Brasil, São Paulo, E.P.U., EDUSP, 1979, pp. 81-161.

19 - See Elly Dekker, “The light and the dark: A reassessment of the discovery of the Coalsack Nebula, the Magellanic Clouds and the Southern Cross”, Annals of Science 47, 1990, pp. 529-560.

20 – Referring to the ignorance of the Portuguese celestial discoveries, Dekker, op. cit., refers “this knowledge never became widely known outside Portugal” and explains it by the “navigational problem that dominated the intellectual climate in Portugal”, the solution of which simply required “a limited knowledge of the southern sky, namely the declination of the Southern Cross”. As far as the astronomical history of the discoveries is concerned, it is symptomatic that most of the highly valuable Portuguese studies of this century had never seen the light in an international scientific language.

21 - Cf. Albuquerque, op. cit., p. 120, our italics.

22 - The map of Mestre João was studied by several historians, namely Luís de Albuquerque, in Livro da Marinharia de André Pires, s/d, pp. 96–97, e Elly Dekker, op. cit. The interpretation presented is a compromise between the interpretations of these authors.

23 - See Silva, op. cit., pp. 200–202.

© Instituto Camões 2003-2005