THE INVENTION OF THE SOUTHERN CROSS

by Eduardo Vila-Echagüe

1. A famous Constellation

Ask a friend anywhere in the world for the name of a constellation in the Southern Hemisphere.
The Cross among
                the stars of Brazil's flag
The Cross among the stars of Brazil's flag
Nine out of ten times his answer will be the Southern Cross. This should not come as a surprise. As far as I know it is the only constellation that has found a place in the banner of several nations. Perhaps you remember those of Australia and New Zealand, but I have found that it also decorates the flags of a couple of almost equatorial countries: Papua Nueva Guinea and Brazil. In the case of the latter, 27 stars are shown depicted on a celestial globe, but the only recognizable constellation is the Cross. It is in a reversed position, of course, because the globe is seen from the outside. In Brazil the presence of the Cross (Cruzeiro in their own language) is not limited to their banner. Their currency was so named during a long period of their history, their westernmost city is called Cruzeiro do Sul and, of course, one of their most popular soccer clubs is also the Cruzeiro.

2. The hidden Pole

One would imagine that such a conspicuous asterism should have been recognized immediately by the first Europeans that crossed the Equator. But in real life things are not so simple, and the Cross had to wait many decades to be identified as such, and for more than a century before finding its present resting place. In fact the story is much longer, tracing its origins to classic times. 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 the fact as a proof of the sphericity of the Earth. But even from Egypt there remained a large part of the sky that never raised above the horizon, into which the ancients were not allowed to place any of the imaginative constellations that covered the rest of the celestial globe.

We have to move 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 Pole which were never 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:
 
 

  I' mi volsi a man destra, e puosi mente
a l'altro polo, e vidi quattro stelle
non viste mai fuor ch'a la prima gente.
  Goder pareva 'l ciel di lor fiammelle:
oh settentrional vedovo sito,
poi che privato se' di mirar quelle!
  I turned me to the right hand, and gave heed
to the other pole, and saw four stars,
never seen save by the first people.
  The heavens appeared to rejoice in their flamelets.
O widowed northern region,
since thou art deprived of beholding these!

Surprisingly, this statement turned out to be absolutely true! In fact, there are exactly four first magnitude stars (α and β Centauri, and α and β Crucis) that had been observed by the Greek, but which could no longer be seen from the Northern Mediterranean in Dante's time. Where did he get his information from? Was it an ancient tradition that did not reach our times? Some Arab traveller passed him the word? Or was he inspired by the four cardinal virtues, as is read in some footnotes of Dante's work? Those four first magnitude stars were probably part of the star catalogue included in the Almagest of Ptolemy, 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 (α 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 takes then place between Virgil and the author (Canto VIII):
 
 

  E 'l duca mio: «Figliuol, che là sù guarde?».
  E io a lui: «A quelle tre facelle
di che 'l polo di qua tutto quanto arde».
  Ond'elli a me: «Le quattro chiare stelle
che vedevi staman, son di là basse,
e queste son salite ov'eran quelle».
  And my Leader: "Son, at what art thou gazing up there?"
  And I to him: " At those three torches
with which the pole on this side is all aflame."
  And he to me: "The four bright stars
which thou sawest this morning are low on the other side,
and these are risen where those were."

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

It is time to go from pure speculation to actual facts. Two hundred years after Dante, the Europeans started moving south. Inspired by their prince, Henry the Navigator, the Portuguese initiated the exploration of the west coast of Africa. As they approached the equator, new stars came into their view. We have the testimony of Alvise Cadamosto, a Venetian sailor in the service of the king of Portugal, who in 1454 wrote from the Gambia river (13° north): "we had seen also six bright and lucid stars low over the sea, and took them as a signal for the compass; ... we judged them to be the Southern Wain, but we could not see the southern pole star itself, which made sense, because we could still see the north pole star." His belief in the symmetry of the heavens was probably inspired in the ancient geographers, many of which had assumed that there was a similar symmetry in the land masses of our own world. The same idea was present in the Astronomicon, a poem written by the Roman astrologer Marcus Manilius, contemporary to the emperor Augustus. When he comes to the Antarctic circle, Manilius features it as the one that encloses the austral Bears.

Our next information about the southern stars comes from none the less than Amerigo Vespucci, the same 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 up to 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 of Dante in the 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 done 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 the almond identical to the Southern Cross? We cannot say for sure.

In a later letter Amerigo Vespucci tells us of another voyage, in 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 seen also 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 3 stars with the shape of an orthogonal triangle, turning in a circumference with a semidiameter of  9.5°." Then he refers to the first of the bright Canopes and provides a rough drawing of it, together with the 3 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
Vespucci's six stars

Though it may be questionable to identify the 2 bright Canopes with the Magellanic Clouds, there is little doubt that the previous figure represents the Southern Cross followed by β and α 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 the proposed identification. There are some other considerations, however, which work against that statement. 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 up to his credibility. For instance, he says that twice the whole crew has seen the rainbow near midnight, or that in those 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 did not have with him his notes any more, which, as he himself says, had been left with the king of Portugal.

Let us 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 recorded in the first 'modern' star atlas, an engraving by the German artist Albrecht Dürer, dated 1515. In this atlas 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

In 1520 Magellan launched his famous expedition, the first that sailed around the globe. One of those few that came back alive to Spain was an Italian, Antonio Pigafetta, who was employed as a kind of secretary to the fleet. This time there is no doubt that the expedition reached at least 54° south, in order to pass through the strait which now is called after its discoverer.

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 3 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 backwards 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 the 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 placed in the southeastern sky. You will also notice that though there are five conspicuous stars in the Cross, only 3 of them (α, β and γ) are really bright, with magnitudes between 1.0 and 1.6. The fourth (δ) is a 3rd. magnitude star, and the fifth (ε) 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.
Australia's Flag
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 do not have a definite answer, but I can try an explanation that probably will not convince many 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 horizontal, and its long arm (γ —> α) 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 be the case, 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.

It had not been Pigafetta, however, the first European to write about the Cross. Not surprisingly it was another Italian, as all the main characters of my story up to this moment. 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 that somehow managed to be on board a Portuguese ship, sent by king Manuel to interchange ambassadors with the mythical Prester John, the Christian king of Ethiopia, 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
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 possible that Pigafetta had seen Corsali's letter before writing the final version of his diary, taking part of his information from him. I am not saying that he had not seen the Cross, but perhaps he had not taken notes about it during the voyage, and his recollections some years later were somewhat confused.
Oviedo's Cross
Oviedo's Cross
It is also possible that by the first years of the sixteenth century the Cross was already 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 sure 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 of the Spanish Pedro de Medina, the first navigation manual ever written, the Cross is used in the same way as Polaris in the Northern hemisphere for finding 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:
 
 

"Já descoberto tínhamos diante,
Lá no novo Hemisfério, nova estrela,
Não vista de outra gente, que ignorante
Alguns tempos esteve incerta dela.
Vimos a parte menos rutilante,
E, por falta de estrelas, menos bela,
Do Pólo fixo, onde ainda se não sabe
Que outra terra comece, ou mar acabe."
"We had already discovered
in that new hemisphere, a new star,
unseen by other people, ignorant
of its presence for a long time.
We saw the part less brilliant and,
for lack of stars, less beautiful,
of the fixed Pole, where yet it is not known
if another land begins, or the sea comes to an end."

We have seen how the Southern Cross became known to most sailors around the world and many learned men in Europe. That should be the end of the story, but really it is not. A most intriguing part is still ahead. I refer to the painful and devious way in which the knowledge of the Southern skies came to the attention of the scientific community. Believe it or not, European astronomers seem to have had a very scanty knowledge of the Cross for most of the 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 Atlases

To track how the Southern Cross obtained academic recognition, it is time to leave literary references and turn towards our next source of information: Star Atlases.

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
Aratus of Soli (from Dürer's 1515 star atlas)
 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 representation of that kind that has reached our times is the Farnese Atlas, dated 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 representation of the celestial or terrestrial globe 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. The beautifully decorated figures, however, have almost no scientific value. The individual stars are not depicted, or if present have no relation to actual stars. When in the sixteenth century the importance of stars for navigation became apparent, those representations were of no use. The 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 find 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 atlas of Albrecht Dürer.
Hood's Star Atlas
Hood Star Atlas - London, 1590
The previous illustration of Aratus is taken from the upper left corner of this atlas. It includes 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 said 1900 years before. A fine example is the atlas of Thomas Hood, published in London in 1590. Both stars and constellations are carefully drawn. The constellation labels provide their names in Latin and Greek, with a summary of the myths related to each one. Yet it 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

Perhaps this was the safest course, after all. There are other atlases from the same period, where the authors tried to improve on the Almagest, with awkward results. A celestial globe, designed by Jacob and Arnold Van Langren, and edited by Petrus Plancius in 1589, shows for the first time two new southern constellations: Crux (or Σταυρος in Greek), and the Triangulus Antarcticus. The four stars and three torches of Dante! Vespucci's triangle and the cross of Corsali and Pigafetta! There is no doubt about it. The names of Corsali and Vespucci (together with Medina) are clearly mentioned as a source, in an empty area of the globe. Though Pigafetta is not there, Crux fits very well with his description; the cross shown is formed by 5 perfectly aligned stars. The only problem is that the Cross and the Triangle are completely misplaced. The Cross is placed where the modern constellation of Reticulum is, nearly 40° from its correct position, while the Triangle is represented with its southern vertex in Chamaleon and the 2 others in southern Carina, with no relation either in position, size or orientation with the present Triangulum Australe.
  
Plancius' Atlas of 1589
Van Langren's Globe of 1589
I guess that the reason for this was that the editors of the globe were more concerned with filling the empty Antarctic circle than with scientific accuracy. They had not even realized that the stars of the Cross had been part of the Almagest star catalogue right from the beginning. Dante knew better! The problem was that those stars had not been identified as a cross, but as the hind legs of the Centaur. If you look back at Hood's atlas which, as I said before, relies entirely on the Almagest, perhaps you will recognize the four stars of the cross placed on top of its right back hoof.

The imagination of the mappers of the skies did not end there. Another much stranger constellation found also 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 of 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 the 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, instead, was already capable of showing all the stars of any importance visible to the naked eye, covering more than 85% of the whole sky.

A century and a half later, geography had enlarged dramatically the knowledge of the Earth. The terrestrial  globes and charts showed entirely new continents and huge oceans undreamt of before. Astronomy, on the contrary, had provided no input at all, 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

This situation was to turn around completely in a few decades. I have to confess that the main reasons for this change were not scientific, but commercial. In the second half of the XVI century there was a fierce competition among cartographers, mainly in the Netherlands. New editions of world maps and globes came out almost every year, each with improved artwork and including the latest discoveries. They were sold both for their scientific and artistic value. Some of the editors thought of enlarging the business by selling celestial globes together with the terrestrial ones. The figures of the constellations allowed more room for the artists to deploy their imagination, as we have shown in some of the previous images, but, on the other side, the scientific content did not improve from edition to edition, or, as we have seen, in some cases decreased. Something had to change.

Cartographers turned to astronomy for help. In the case of the stars visible from Europe, they required a new star catalogue with less 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 with unprecedented accuracy the stars visible from his native Denmark. But there was no Tycho in the southern lands.

An enterprising Dutch 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 a few other new northern constellations. 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 in 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 the new observations in his hand, Plancius distributed the previously uncharted area in 12 new constellations. He also recognized the true position of the Cross. The new constellations appeared for the first time in a globe designed by Jodocus Hondius, in 1598, and in 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 charts, introducing for the first time the usage of Greek letters to label the brightest stars of each constellation.

In Bayers' atlas the sky was divided in 48 individual plates, one for each of the traditional constellations, plus an additional plate that grouped the twelve new ones introduced by Plancius.
Bayer's Cross
Bayer's Cross
The Cross was shown in the same plate as the Centaur, covering part of its hind legs. Finally the Cross reached its right place in the sky! What about its position? The longest arm should be pointing south, and the short arm should point to β Centauri, which is the star labeled by Bayer with the Greek letter γ, at the front legs of the Centaur. It can be seen that Bayer's Cross is rotated about 45° to the left. Do not get 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 left of those lines, in a direction roughly perpendicular to the body of the Centaur.

The explanation seems to be that Bayer is not using for the Cross 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 Guide7 by Project Pluto, with the optional Almagest Star Catalogue contributed by me, I have prepared a chart with the real and Almagest stars for the epoch 1600. Both its orientation and the grid are for ecliptical coordinates, to match Bayer's chart. The 2 bright stars on the left are α and β Centauri. The actual cross are the four colored stars to the left of the label 'Cru'. The Almagest stars are depicted as white disks 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
The Cross in 1600, together with the Almagest stars.

The first document 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."
Honidius and Veen globe
Hondius and Veen globe of 1613
It is interesting to note that though the label is in Latin, the cross name, Cruzero, is in Spanish. The same name with slightly different spellings (Crusero, Crucero, Cruceiro...) can be seen in many old star maps and globes, starting with Corsali's pioneer drawing of 1515, and its usage continued well into the XVIII 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 born 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 one scientist or the other. 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

The first accurate observations of the southern stars were performed by Edmund Halley from the island of St. Helena in 1676. When his catalogue was known in Europe, the Cross finally found its resting place, putting an end to a search that had started 2000 years before. It is remarkable to find the name of St. Helena associated to our Southern Cross, because she, the mother of the emperor Constantine, had been the discoverer of the original Cross in the hill of the Golgotha, 300 years after the Crucifixion. Every year, on the 3rd. of May the Church commemorates this discovery with a festivity named "The invention of the Holy Cross", which inspired the title of this essay. The date was so chosen because on May 3, 628 the emperor Heraclius recovered from the Persians the piece of the Cross that had been left by Helena at Jerusalem, the other two parts having been sent to Rome and Constantinople.

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 whole skies,
Schiller's Northern Cross
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 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, as can be seen in the attached figure. But his innovations did not prevail, and the Cross finally stayed in the south.

Had the Cross any influence in 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!