It is one of the images most closely linked to Christmas. The star that guided the Three Wise Men of the East to the very portal of Bethlehem, where the baby Jesus had just been born. Now, what exactly did Melchior, Gaspar and Baltasar see? Was he really a star? Or perhaps a comet, a supernova, a meteorite, or even a simple conjunction of planets? Science has tried to explain the phenomenon and verify, as far as possible, its veracity. These are the results.
To find out what type of astronomical phenomenon was observed by the Three Wise Men, the first step is to establish the dates with the greatest possible precision. And at this point the Bible does not help much, since it does not say anything about the exact day of Jesus' birth, although it does relate the fact to historical events and figures, such as the reign of Herod.
Historians agree that the King of Judea must have died sometime between 4 and 1 BC. And the Three Wise Men visited him shortly before his death, so his trip (and the appearance of the star that guided them) had to occur before those dates.
On the other hand, there are serious doubts that the birth of Jesus took place on December 25. In the Bible, Saint Luke speaks of the activity of the shepherds of the area on the days of birth, caring for their flocks and newborn lambs during the night, something that happens in spring, and not in the middle of winter.
Furthermore, December 25 is precisely the date on which the Romans, who dominated the region at that time, celebrated their Saturnalia, one of their most important festivities and for which streets and houses were decorated and gifts were exchanged. It is no coincidence that, to avoid being persecuted, the first Christians chose precisely that date to celebrate the birth of Jesus Christ. Later, in the 4th century, when Emperor Constantine officially adopted Christianity, December 25 was preserved as Christmas Day.
But back to the question of the year. Today historians agree that the birth of Jesus did not occur 2011 years ago. And the chronology we use, which divides the years into AC (Before Christ) and AD (After Christ), and which was conceived by the Roman monk Dionysius the Exiguus in 523 AD, contains at least two errors. significant.
The first is to place the year 1 AD immediately after the year 1 BC, without going through zero, an essential number in current mathematics and which, in fact, subtracts a year from any date we want to consider.
And the second is that Dionysius accepted Clement of Alexandria's statement that Jesus was born in the 28th year of the reign of Emperor Caesar Augustus, without taking into account that during the first years of his rule he was known by his original name, Octavian, until the Senate proclaimed him "Augustus" four years later. By the time the error was discovered, the chronology that we still use today was too established to change it and correct the four years of lag.
In summary, taking these errors into account, the birth of Jesus must have occurred in spring, and between the years 7 and 2 BC. So that is the time frame that astronomers must investigate to verify if any event occurred in the sky capable of so powerfully attracting the attention of the Three Wise Men of the East.
Four possibilities
From a purely astronomical point of view, there are four possibilities to explain the Star of Bethlehem. The first is that it was a meteorite, but it is very unlikely due to the fact that meteorites, which become a fireball upon entering the atmosphere, only last a few seconds before disappearing, and the star of Belén shone for entire weeks.
The second possibility is that it was a comet, objects that, this time, can shine in the sky even for months. However, the most spectacular of all known comets, Halley, whose orbit brings it close to Earth every 76 years and which was last seen in 1986, was visible in Judea during the months of August and September of the year 11. AD, which does not coincide with the dates of Jesus' birth. Of course, it could have been another comet, one that passed by then and has not yet returned, but that is something we can never be sure of.
Furthermore, in ancient times comets were seen as signs announcing death and destruction, and not as heralds of the birth of a king or a god. The Romans, for example, marked the death of General Agrippa using the apparition of Halley in 11 AD.
Another possible explanation, the third, is that what the Magi saw was the violent death of a star. And that leads us to two different possibilities: a nova or a supernova. In the first case, it is the way (a thermonuclear explosion) in which a star is suddenly freed from an excessive accumulation of hydrogen on its surface.
It is very spectacular, if the star is close enough, and its appearance takes place unpredictably and at any time. The brightest ones appear suddenly, without warning, like a spectacular new light in the sky. Its brightness, after a few days, or even weeks, fades until it disappears completely.
On average, a nova visible from our planet occurs once every twenty years (the last one was in 1975), so nothing prevents this, and no other, from being the phenomenon seen in Judea or the three Wise Men of the East. .
Much more spectacular, although less common to see, is a supernova, the catastrophic explosion of an entire star that reaches its end and whose brightness even eclipses that of the entire galaxy that contains it. At the time of the explosion, a supernova can be seen even in broad daylight, and its brightest brightness can last for months before it begins to fade.
During the last thousand years, Humanity has witnessed four supernovas, in the years 1006, 1054, 1572 and 1604. In all cases, the chroniclers of each era referred profusely to the phenomenon. The Chinese, for example, report that the supernova of the year 1054 was visible for two months even in broad daylight.
The downside is that at the time of Jesus' birth there is no definitive reference to the sudden appearance of a particularly intense light in the sky. If it happened, no one, in any culture, documented the event, which seems to indicate that we must look for the solution somewhere else. Some Chinese texts speak of a possible nova in the spring of the year 5 AD, but they refer to it as a phenomenon of little importance and little, if any, spectacularity.
The last (and perhaps most likely) explanation is the possibility that the Three Wise Men witnessed a particularly bright planetary conjunction, enough to make them believe that it was a new star. But was there any planetary conjunction of this type between the years 7 and 2 BC? The answer is yes. Astronomers have determined that, in that time interval, several planetary phenomena occurred that could have been interpreted as the Star of Bethlehem.
The first of them was in the year 6 BC, it occurred between the planets Mars, Jupiter and Saturn and happened in the constellation of Pisces. The three worlds formed a brilliant geometric figure in the sky that must have been of great beauty and capable of attracting anyone's attention. Another possibility is the "triple conjunction" of Jupiter and Saturn between the months of May and December of the year 7 BC. Jupiter's "passes" over Saturn occurred on May 29, September 30, and December 5 of that year.
There is no doubt that all these events were perfectly visible, since they happened on the night side of the Earth. The two planets, in addition, shone very close to each other for eight long months, the time estimated to be necessary for the Three Wise Men to cover nearly a thousand km. distance between Babylon and Judea.
However, what was surely the brightest of the planetary conjunctions of that time was the one between Venus and Jupiter in the constellation of Leo on August 12, 3 BC.
The two planets shone that day extraordinarily close to each other. And when Venus withdrew, Jupiter remained with Leo for at least ten more months, adding its brightness to that of the star. If the meeting of the three Wise Men with Herod occurred during the spring of 2 BC, the dates would fit perfectly. In fact, after their first meeting and after Jupiter and Leo continued to shine together in the sky, Venus returned to the area and aligned with Jupiter in June 2 BC. On the 17th of that month the brightness of the two planets was so intense that they became confused.
Venus and Jupiter slowly descended together towards the horizon as their brightness became one. By eight-thirty in the afternoon, local Jerusalem time, they had practically merged into a single, luminous star. At a time when there were no observing instruments or sunglasses, it is very likely that observers were not able to distinguish the two individual objects and only perceived a single bright flash over the skies of Judea.
Was this what the Three Wise Men saw? It is difficult for science to ensure this. The only certainty is that these alignments occurred, and that they were clearly visible in a time that coincides with that of the biblical story. Beyond that, there are no absolute certainties. Everyone is free, therefore, to draw their own conclusions.