THE INVENTION OF THE SOUTHERN CROSS

1. A famous Constellation

The Cross among the stars of Brazil's flag

2. The hidden Pole

It all began when the Greeks started thinking of the starry heavens as a hollow sphere. Gradually it became apparent to them that from where they lived, only a part of the sphere could be seen. The size of the invisible area varied according to the latitude of the observer. Aristotle already knew that there were stars known to the Egyptians which could not be seen from Greece, and used that fact as proof of the sphericity of the Earth. But even from Egypt there remained a large part of the sky that never rose above the horizon, into which the ancients were not allowed to invent imaginative constellations like those that already covered the rest of the celestial globe.

We have to go to Italy to find the first speculation about the content of that forbidden zone. In the last book of Cicero's Republic, the author imagines a dream of Scipio Aemilianus, at the siege of Carthage, in 149 B.C. His grandfather, the great Scipio Africanus, appears in front of him and somehow takes him to a place in the Milky Way. In young Scipio's own words: "As I gazed out from where I stood, the whole prospect looked marvelously beautiful. There were stars we never see from this place, and they were larger than we could possibly have imagined."

Cicero's Republic  was lost in the Middle Ages with the exception of Scipio's Dream, which was preserved in a Commentary written in Rome by Macrobius, at the close of the fourth century. In that book Macrobius leaves no doubt that Scipio is speaking of the stars near the South Celestial Pole which could never be seen from the Roman world. This Commentary was widely read in Medieval circles. It probably was the inspiration of Dante Alighieri (thirteenth century), who in his Divine Comedy, at the beginning of the Purgatory (Canto I), says these mysterious words:
 
 

Surprisingly, this statement turned out to be absolutely true! In fact, there are exactly four first magnitude stars (a and b Centauri, and a and b Crucis) that had been observed by the Greeks, but which could no longer be seen from the Northern Mediterranean in Dante's time. Where did he get his information? Was it an ancient tradition that did not reach our times? Some Arab traveler passed him the word? Or was he inspired by the four cardinal virtues, as suggested in some footnotes of Dante's work? Those four first magnitude stars were probably part of the star catalogue included in Ptolemy's Almagest, which became available in Europe (in Latin translations) a century before Dante's birth. But it is unlikely that this was his source, because those stars, if present, are grossly misplaced and only one of them (a Centauri) is labeled as first magnitude.

There is another astronomical reference in Dante's Purgatory  which is not as well known. It is also relevant to our story, as we will see later. The sighting of the four stars had happened just before dawn. After a long day had passed, it was dark once more. The following dialogue then takes place between Virgil and the author (Canto VIII):
 
 

Four bright stars and three 'torches' near the south pole! Did they have any influence in later generations? Let us continue our story.

3. Moving South

Our next information about the southern stars comes from the well known Amerigo Vespucci, the explorer that gave his name to the New World. In a letter recounting a voyage that probably took place in 1499, he claims to have followed the coast of Brazil reaching a point 6° south of the Equator. He had searched in vain for the south pole star, but found none closer than 10° to the pole (in fact, 3rd. magnitude b Hydri was just at that distance in the fifteenth century). Then he remembers the words in Dante's Purgatory, about the four bright stars. After quoting the lines in full, he says: "It is my belief that in those verses the poet wants to describe with the four stars the other pole of the firmament, and up to now I have no doubts about the truth of his statement, because I noticed four stars in the shape of an almond which had little movement." Later in the letter we are told that these observations were made in July and August. At that time of the year, Crux is already past the meridian, in an inclined position, and is not easily recognizable as a cross. Is Vespucci's almond our Southern Cross? We cannot say for sure.

In a later letter Amerigo Vespucci tells us of another voyage, during which he had a much better opportunity to observe the southern stars. In his narrative he says that they attained a latitude of 50° south. He dedicates several paragraphs and a couple of sketches to the southern sky. He starts by saying that he has noticed nearly 20 stars as bright as Venus or Jupiter. Then he mentions that he has also seen three 'Canopes' in those regions, two of them bright and the other obscure. The region near the pole is described with these words: "There are three stars with the shape of an orthogonal triangle, turning in a circumference with a semidiameter of  9.5°." He then refers to the first of the bright Canopes and provides a rough drawing of it, together with the three stars forming the triangle. Two other stars come after this group, revolving at a distance of 12.5° from the pole. They are followed by the second bright Canope. His description continues with the words: "After these come other 6 stars, the most beautiful and bright among all the others of the eighth sphere, the semidiameter of their circumference measuring 32°. Together with them moves a black Canope of immense magnitude. They are seen in the Milky Way, and when crossing the meridian they show the following shape :"
 

Vespucci's six stars

Though there may be some question as to whether or not Vespucci's two bright Canopes are the Magellanic Clouds, there is little doubt that the previous figure represents the Southern Cross followed by b and a Centauri. The distance to the pole, the fact that in no other part of the sky you will find such a concentration of first magnitude stars and, above all, the placing of the black Canope exactly where the Coal Sack is, all argue in favor of this proposed identification. There are some other considerations, however, which work against that claim. There are scholars that think that this letter is a fake and that Vespucci never reached those southern latitudes. His geographical descriptions are as vague as those of the bright Canopes. His other astronomical observations do not add to his credibility. For instance, he says that twice the whole crew has seen rainbows near midnight, or that in those faraway places the New Moon is visible on the same day of its conjunction with the Sun. Another possibility is that he wrote the letter several years after the voyage, at a time when he no longer had his notes, which, as he himself says, had been left with the king of Portugal.

Let us now go back to our story. What do we have up to now? Descriptions of a southern wain, an almond, a triangle, Canopes, but not a single word about a cross. In fact none of these asterisms are displayed in the first 'modern' star chart, the woodcut planispheres of the northern and southern sky published by the German artist Albrecht Dürer, in 1515. In his southern planisphere the area of the sky not visible in Hellenistic times is still left empty, roughly a circle somewhat eccentric to the sixteenth century southern pole.

4. Literary Descriptions

Pigafetta kept a diary throughout the voyage. In it we are told about the giant inhabitants of the Patagonia and the language they use, the three months of navigation across the Pacific Ocean without seeing any inhabited land, the death of their commander in the Philippines, and finally the long way home sailing west around the tip of Africa. But Pigafetta also had time to write about the stars. In a recollection placed in his diary after the crossing of the Pacific, he says "The Antarctic pole has not the same stars as the Arctic. Near the pole there can be seen many small stars clustered together, in the like of two nebulae not far apart from each other and somewhat obscure, in the middle of which there are two very big stars, not very bright and with little movement." It is my guess that the two nebulae are a reference to the Magellanic clouds, while the two big but not very bright stars may be the globular cluster 47 Tucanae, near the Small cloud, and the Tarantula nebula in the Large one.

After a digression related to the deviation of the compass from true North, he proceeds by telling us that in those seas they saw a cross of five very bright stars, right to the west and very well adjusted the one with the other. His exact words in Italian are: "Quando èramo in questo golfo vedessimo una croce de cinque stelle lucidissime, dritto al ponente e sono giustissime una con l'altra." A cross at last, described by a fairly reliable witness! Obviously it should be our Southern Cross, what else? But can we be sure? Let us cross check his description.

Magellan moved out of the strait on November 28, 1520. By the end of January they would have left the Southern Hemisphere. Pigafetta's cross was probably seen in December or early January. The nights in those latitudes were short. In fact, when going through the strait they never had complete darkness. Is it possible that they saw the Southern Cross placed 'right to the west'? You can perform the exercise yourself, with any planetarium software available in the market. To your surprise you will find that at that time our Cross was seen at the left of the pole, roughly towards the southeast. You will also notice that though there are five conspicuous stars in the Cross, only 3 of them (a, b and g) are really bright, with magnitudes between 1.0 and 1.6. The fourth (d) is a 3rd. magnitude star, and the fifth (e) is more than half a magnitude dimmer. And definitely only the first four fit into the pattern of a cross, as can easily be seen in the banner of Australia.

The 5 Stars in the Banner of Australia

Did Pigafetta see some other asterism? Take my word that there was nothing in those western skies that resembled in any way the cross described by him. In fact those areas are especially dull, with almost no first or second magnitude stars. What did he see, then? A bunch of novas, meteorites, angels, flying saucers, fires of St. Elmo? I don't have a definite answer, but I can suggest an explanation that may not be convincing to all of my readers.

What if the words 'dritto al ponente' really meant something like 'pointing right to the west'? While slowly turning clockwise around the pole, there will be a moment when the Cross is seen horizontally, with its long arm (g -> a) pointing due west. We should also be prepared to accept that 'sono giustissime una con l'altra' only means that the five stars were packed in a small region of the sky, without any implication about their relative positions. Whatever the case may be, there is little doubt that most Europeans heard of the Cross for the first time when they read the narrative of that incredible circumnavigation around the world.

However, Pigafetta was not the first European to write about the Cross. Not surprisingly the first one was another Italian, as all the main characters of my story up to this point. While the Spanish and Portuguese were unveiling the 'terra incognita' of the ancient maps, it seems that the Italians were the real discoverers of the southern skies. The name of this gentleman was Andrea Corsali. He was a Florentine diplomat who somehow managed to be on board a Portuguese ship, sent by king Manuel to exchange ambassadors with the mythical Prester John, the Christian king of Ethiopia, a nation which for many centuries had remained completely isolated from their brethren in faith.

In a letter sent to Guiliano de Medici, written in India on January

Corsali's Cross

6, 1515, Corsali offers the following description: "Here we saw an admirable order of the stars, which turn endlessly in that part of the sky opposite to ours. The place of the Antarctic pole is shown by two clouds of considerable size, which walk continually around it, now going upwards, now downwards. There is a star placed in the middle of the two clouds, which revolves with them at about 11 degrees from the pole. Over them appears a marvelous cross in the middle of 5 stars which, together with other stars nearby, turn around the pole at a distance of 30 degrees, like the Cart does with the Northern Star. It make its course in 24 hours, and it is so beautiful that I think no other celestial sign can be compared to it, as can be seen in the drawing below."

The information provided by Corsali is much more accurate than all the references we have mentioned before, and leaves no doubt about the identification. I even consider it possible that Pigafetta had seen Corsali's letter before writing the final version of his diary, taking part of his information from that document. I am not saying that Pigaffetta had not seen the Cross, but perhaps he had not taken notes about it during the voyage, and his recollections years later were somewhat confused.

Oviedo's Cross

It is also possible that by the first years of the sixteenth century the Cross was already well known to the Portuguese and Spanish sailors all around the world, and that really Corsali and Pigafetta did not discover anything, but only put in writing that common knowledge. In the 'Historia General y Natural de las Indias', dedicated by Gonzalo Fernández de Oviedo to the emperor Charles V, printed in Toledo, Spain, in 1526, we find the following reference: "There is another remarkable thing I want to say, that those who have not sailed to the Indies cannot have seen, except if they have gone towards the equator or at least have been less than 23° from it. This thing is that, looking south, 4 stars forming a cross are seen over the horizon, turning around the Antarctic circle and placed in this way: "

Considering that Pigafetta's diary was completed at the end of 1524, and that it circulated in manuscript form only, it is almost certain that Fernández de Oviedo, who had started writing his History several years before, had known of the Cross independently of Corsali or Pigafetta.

Another book written a few years later, in 1538, implies that the Southern Cross could be easily recognized by the sailors of the Southern Seas. In the Cosmografía by the Spaniard Pedro de Medina, the first navigation manual ever written, the Cross is used in the Southern hemisphere, in the same way as Polaris in the North, to find the latitude at sea.  Medina's words are: "It is necessary to know that the signs to recognize the Antarctic Pole are four stars disposed as a cross. These stars are not one of the signs of the Zodiaque, nor any of the other 35 constellations of the sky. Their name is Crucero. One of these four stars is called the head, another the foot, and the two others the arms. To know which is which, you must know that the one at the foot is greater than the others. When the cross is standing upright, the one at the foot is closer to the horizon, and its distance to the Antarctic Pole is 30 degrees."

To put an end to this part of the narrative, let me add a final quote, not for its documentary value but because of its literary beauty. It is taken from the Lusiadas, the great Portuguese epic poem written by Camoens in 1572. The following verses probably refer to the Cross:
 
 

We have seen how the Southern Cross came to be known to most sailors around the world and many learned men in Europe. That should be the end of our story, but it is not. A most intriguing part still lies ahead. I'm  referring to the painful and devious way in which knowledge of the Southern skies came to the attention of the scientific community. Believe it or not, European astronomers seem to have had very scanty knowledge of the Cross for most of the sixteenth century. Scholars were too busy rediscovering antiquity, to waste their time with the real world. They gave more consideration to a phrase in Aristotle or Ptolemy, than to any report from the newly discovered lands. If in 1610 they were to deny the reality of the spots on the Sun or the moons of Jupiter, visible through Galileo's telescope,  why should they believe in stars they had never seen?

5. Star Maps

The first known description of the starry heavens is a Greek poem named Phaenomena, written in 270 B.C. by Aratus of Soli. It includes a thorough description of the constellations known to the

Aratus of Soli (from Dürer's 1515 star charts)

 ancients, but almost no references to individual stars. It soon became a literary classic, being translated to Latin by such personalities as Cicero and Germanicus Caesar. The only surviving work of Hipparchus, the greatest astronomer of antiquity, is a commentary, or rather a criticism, of the poem of Aratus. The New Testament has only three references to books by pagan writers, the Phaenomena being one of them.

Other literary descriptions followed. It was only a matter of time for shapes of the constellations to be shown in graphical form. The best known ancient representation of this kind that has reached our times is the Farnese Atlas, dated circa 200 B.C. It is a celestial globe on the shoulders of the giant Atlas, with the mythological constellations embossed on its surface. By the way, this is the reason why up to this day any collection of celestial or terrestrial maps is called an atlas. The poor giant did not labor in vain!

Some manuscripts have come to us from the middle ages with representations of the constellations. These beautifully decorated figures, however, have almost no scientific value. The individual stars are not depicted, or if present bear no relation to actual stars. When in the sixteenth century the importance of stars for navigation became apparent, those representations were of no use. Observation of the stars could provide an accurate value for the latitude and, in some cases, a rough knowledge of the longitude. Without a good star chart, it was not easy for navigators to figure out the right star in the sky. Believe it or not, Columbus, the Admiral of the Ocean Sea, made a mistake in the identification of Polaris, and computed the latitude of the Antilles as that of New York!

We have already mentioned the first modern star charts of Albrecht Dürer.

Hood Star Atlas - London, 1590

The previous illustration of Aratus is taken from the upper left corner of his Northern planisphere. These charts include only the stars and constellations listed in the Almagest, which was still the best and only star catalogue available in the West. This may have been reasonable in 1515, but the same pattern continued through most of the sixteenth century. While terrestrial maps included new discoveries in each subsequent edition, the skies continued as immutable as Aristotle had stated 1900 years before. A fine example are the planishpheres of Thomas Hood, published in London in 1590. Both stars and constellations are carefully drawn. The constellations are labeled in Latin and Greek, with a summary of the myths related to each one. Yet Hood relies entirely on the Almagest, even where it is wrong. As a consequence, the area around the South Pole is left empty. The author prefers to ignore all the knowledge acquired during the more than one hundred years of discoveries in the southern lands and seas.

6. Antarctic Confusion

Van Langren's Globe of 1589

The imagination of the celestial cartographers did not end there. Another much stranger constellation also found a place in the previously uncharted area. It was pointed to me by my friend Ray Harris, an expert in ancient star charts. In fact it was he who brought all this matter to my attention, and who provided most of the information related to this part of my story. This constellation is a human figure placed near the Southern Pole, with the very appropriate name of Polophylax, which in Greek means the Guardian of the Pole. I think its purpose is to provide a southern counterpart to the constellation Arctophylax (also known as Bootes), which translates as the Guardian of the Bears.

Let us recapitulate. At the beginning of the era of discoveries knowledge of our globe and of the skies was derived almost entirely from the two classic books of Ptolemy: the Geography and the Almagest. The first contained a rather inaccurate description of less than a quarter of the surface of the Earth, just including Southern and Central Europe, Africa north of the Sahara and a part of Western and Southern Asia. The Almagest, unlike the Geography, was already capable of showing all the naked eye stars of any importance over more than 85% of the entire sky.

A century and a half later, knowledge of the Earth's geography had been enlarged dramatically. Terrestrial  globes and charts showed entirely new continents and huge oceans undreamt of before. Astronomy, on the other hand, had no improvements to offer, and the only additions that celestial cartographers could make  were a few misplaced or imaginary constellations based on ambiguous reports of navigators, written many decades before.

7. Cruzero Hispanis

Cartographers turned to astronomy for help. In the case of stars visible from Europe, they required a new star catalogue with fewer errors than those in the Almagest, and with more accurate positions. For the southern stars, they needed measurements to replace the purely descriptive accounts received from navigators. The first requirement was met by the work of the greatest astronomer of the period, Tycho Brahe, who since 1575 had been observing the stars visible from his native Denmark with unprecedented accuracy. But there was no Tycho in the southern lands.

An enterprising Dutchman found a typical business solution. If there is no southern Tycho, let us make one! We have met this man already. He is the same Petrus Plancius who had placed (or misplaced) the Cross and the Southern Triangle for the first time on a celestial globe, as well as Polophylax and a few other new northern constellations on his celestial charts. When the first Dutch expedition set sail for the East Indies in 1595, Plancius asked its pilot, Pietr Keyser, to make 'state of the art' observations of the southern stars. Keyser, who observed from Madagascar and Sumatra, died during the journey. His work was compiled by Frederik de Houtman, the chief of the expedition, and sent back to Plancius. Houtman made additional and improved observations in a second voyage, in 1598, which he published as a catalogue when he came back, some years later.

With these observations in hand, Plancius populated the previously uncharted area with 12 new constellations. He also recognized the true position of the Cross. The new constellations appeared for the first time on a globe designed by Jodocus Hondius, in 1598, and on a later one issued in 1603 by Willem Blaeu, a former collaborator of Tycho Brahe. It was also in 1603 when the Bavarian Johannes Bayer published his famous star atlas, introducing for the first time the usage of Greek letters to label the brightest stars of each constellation.

In Bayer's atlas the traditional constellations were displayed on 48 individual plates, one for each of them, plus an additional plate that grouped the twelve new ones introduced by Plancius.

Bayer's Cross

The Cross was shown on the same plate as the Centaur, covering part of its hind legs. Finally the Cross found its correct place in the sky! What about its orientation? The longest arm should be pointing south, and the short arm should point to b Centauri, which is the star labeled by Bayer with the Greek letter g, at the front legs of the Centaur. It can be seen that Bayer's Cross is rotated about 45° counterclockwise. Don't be confused by the almost vertical lines in the chart. They are not meridians but great circles that pass through the poles of the ecliptic. The real south is many degrees to the left of those lines, in a direction roughly perpendicular to the body of the Centaur.

The explanation seems to be that for the Cross Bayer is not using the new positions recorded by the Dutch, but those of the venerable Almagest. In fact, most of the stars shown in this part of Bayer's chart are barely recognizable in a modern atlas. Using the astronomical program Guide 8 by Project Pluto, with the optional Almagest Star Catalogue which I contributed, I have prepared a chart showing both the actual star positions and those obtained from the Almagest, precessed for the epoch 1600. The chart's orientation and grid are for ecliptical coordinates, to match Bayer's chart. The two bright stars on the left are a and b Centauri. The actual cross is marked by the four colored stars to the left of the label 'Cru' which are connected by lines.. The Almagest stars are depicted as white with pink diagonal spokes. Bayer probably made up his cross with the 4 leftmost Almagest stars of the 5 seen in the lower part of my chart, though his positions are only approximate.
 

The Cross in 1600, together with the Almagest stars.

The first record I have seen showing the Cross in about its proper place and with the right orientation is a celestial globe edited in 1613 by Jodocus Hondius Junior and Adrian Vaen. Here the Cross is labeled as a separate constellation. The label is written in Latin, meaning: "The Spanish Cruzero, but  the Centaur's feet in Ptolemy."

Hondius and Veen globe of 1613

It is interesting to note that though the text is in Latin, the label, Cruzero, is in Spanish. The same name with slightly different spellings (Crusero, Crucero, Cruceiro...) can be seen on many old star maps and globes, starting with Corsali's pioneer drawing of 1515, and its usage continued well into the eighteenth century. In modern Spanish the constellation is named Cruz del Sur, but in Portuguese it is still called Cruzeiro, its original name. The Latin name, Crux, used for the previously misplaced Cross, was reluctantly applied to the new one. It became prevalent only many decades later, which is the more surprising because absolutely all the other new constellations were created with Latin names. In the Almagestum Novum of 1651, written by Father Riccioli in Latin, the constellation is already called Crux or el Crosiero. In 1671 the French Astronomer Augustine Royer expanded its name to Crux Australis. In the chart published in 1690 from the observations of the German astronomer Hevelius, the constellation is called Crux, as in the present times.

The fact that the Cross was born with a Spanish name is not irrelevant. It is another argument in favor of the popular origin of this constellation, in contrast with all the other modern 'Latin' constellations which were artificial constructions of cartographers or astronomers. This puts our Southern Cross in the same category as the traditional constellations of the Greeks, most of which can trace their pedigree to the Chaldeans and the Sumerians. The Cross turns out to be the only 'natural' constellation of our times.

8. The other Cross

This brings us to our last subject: the religious significance of the Southern Cross. There can be no doubt that for those Spanish and Portuguese sailors thousands of miles from home, the sight of the Cross up in the sky must have been a source of comfort amidst their sufferings and fears. In those days of miracles and wonders, it was all very natural that the most precious symbol of their Faith preceded them in the conquering of the new worlds in the name of the Cross.

The difference between the Christian Cross of the South and the northern pagan constellations was notorious. In the seventeenth century there was even an attempt to Christianize the entire sky,,

Schiller's St. Helena and the (Northern) Cross

replacing the old pagan figures with prophets and saints, and very appropriately the 12 zodiacal signs with the 12 apostles. The author of this proposal was Julius Schiller, who in 1627 included the new constellations in his celestial atlas Coellum Stellatum Christianum. The paradox is that he left out the only really Christian constellation, our Southern Cross, putting in its place the figures of Abraham and Jacob. He moved the Cross to the north, replacing Cygnus with the figures of St. Helena and Cruci Christi, as can be seen in the attached figure. But his innovations did not prevail, and in the end the Cross remained in the south.

Did the Cross have any influence on the history of the Southern Hemisphere? We all know that the conquistadors seem to have made more use of the sword than of the cross in the colonization of those new lands. Yet the cultures that emerged from that process were in no way void of the moral values represented by the Cross, and we cannot say that the nightly contemplation of those 4 stars, placed in the most beautiful part of the sky, had not a positive influence in the hearts of those sailors, priests, soldiers, farmers and workers of every type that lived and still live in the South. After all, who can deny that this hemisphere turned out to be much more peaceful than the old one, and that either by their own efforts or through divine protection the Southern people have managed to keep their part of the world out of most of the wars that have plagued mankind in the twentieth and already in the twenty first centuries!