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The Cosmology of the Magi

What was the Christmas Star? Was it a comet, a novae, a supernovae or a grouping of planets? Astronomer, Fr Christopher Corbally, from the Vatican Observatory in Arizona, explores several theories.

Right off, and I am sorry if I disappoint you, but I don’t think we know what the Christmas Star was. So why should you bother reading further? Well, by looking into the question we can come to some understanding of the impact of the heavens on the lives of the ‘wise men’, the Magi, and of the significance of the ‘Star’ to them and so to us. It is going to further our understanding of the Incarnation, so we too can ‘do him homage.’

If we believe that the Christmas Star was purely a miraculous sign in the sky, then this cannot be proved or disproved by science, and we don’t get any further in understanding the Magi. But if we start by proposing it was an astronomical event, then there are several candidates: a comet, a suddenly brightening star, or some grouping of planets.

To sort between these we first need to establish the date of birth for Jesus. This can range, depending on the historian you consult, between 8 BC and 1 A.D. There were several recorded comets in this period, such as one in 5 BC, but a comet has something serious against it; it was taken as a sign of bad rather than good omen. This was so widely accepted that Augustus Caesar had quite a spin-doctoring job to persuade people that the comet which appeared in 44 BC was the assassinated Julius Caesar’s wandering soul and so to be honoured, rather than to be feared (or welcomed!) as a sign of Augustus’s own demise. So the general consensus among Christmas Star experts is that it was not a comet.

The general consensus among Christmas Star experts is that it was not a cometThere are two kinds of strongly brightening stars, novae and supernovae. Novae and one type of supernovae brighten when the outer material from one star is pulled over by a close companion star, reaches a critical mass, and ‘goes nuclear’. Never fear, our own Sun is too far from any neighbouring star to have this happen around us. Another type of supernova occurs as a star, 10 times or more massive than our Sun, comes to the end of its life, and first implodes and then dramatically explodes. As the name implies, a supernova is a very much more energetic event than a nova, but just how bright either appears to us on Earth depends on its distance from us. The brightest of the supernovae have been seen even during the day before they faded away.

Now there are two counts against the Christmas Star being a nova or supernova. The Chinese, who were reliable recorders of these ‘guest stars’, as they called them, did see one in 5 BC, but there is no Western account of it, which would be odd if it were the star that appeared to the Magi. Indeed, the Romans did not seem to pay much attention to these fleeting visitors or give them any ‘kingly’ significance.

In the time of the Magi, astronomers were synonymous with astrologers – but just try today calling a professional scientist an astrologer!Further, if the nova/supernova was bright, it would have been seen by Herod and the people of Jerusalem, who would have known exactly when it appeared, and so Herod would not have had to consult the Magi privately for this information (Matthew 2:7). That reasoning obviously applies to comets too.

So that leaves what has intrigued most astronomers who tackled the Christmas Star question, some kind of grouping of planets in a significant part of the sky. To the Magi planets would appear to be as pinpoint-like as stars, save that they move against the background of the fixed stars. Hence comes our name for them, planets, from the Greek for ‘wanderers’. For the Magi each planet, whose motions through the stars in the signs of the Zodiac were well studied and could be predicted, had a unique significance. In the time of the Magi, astronomers were synonymous with astrologers – but just try today calling a professional scientist an astrologer!

So what grouping of planets in what constellation would have sufficient meaning to propel them onto their camels and start a long journey across the desert? (Note that the Magi could have set out before actually seeing the ‘conjunction’ of planets, as it is called, since they had sufficient expertise to predict that it would happen.) Here is where each modern astronomer, back to the time of Johannes Kepler, more or less agrees. It would have been a triple conjunction, involving the meeting three times of two planets (or a planet and a bright star) in a short period of time. There was a particularly strong show in 3 BC that started on 12 June with Venus very close to Saturn, followed by a spectacular pairing of Venus and Jupiter on 12 August in the constellation of Leo, which was associated with the Jews, and completed between September 3 BC and June 2 BC by Jupiter, the kingly planet, passing the bright star Regulus (yes, the king star) in Leo three times.

But there was another strong triple conjunction in 7 BC, this time of Jupiter and Saturn in the constellation Pisces, again associated with Israel, and this is favoured by other researchers. Indeed, a recently deceased astronomer at the Vatican Observatory went with a proposal which had noted an interesting alignment on 12 November, 7 BC, of Jupiter and Saturn at the apex of the cone formed by the zodiacal light as viewed from Jerusalem. This made a beam of light appear to fall from the two planets down onto Bethlehem, just like some Christmas cards depict.

God uses our science and reasoning to draw us to himselfWe are not finished. Some will point to an amazing sequence of astronomical phenomena. It started with the above triple conjunction of summer and autumn in 7 BC, continued with a planetary massing in Aries in the spring of 6 BC, then some planetary pairings in Pisces in February 5 BC (the Moon and Jupiter, Mars and Saturn), and finally the above mentioned ‘guest star’ in March 5 BC. One after the other these would surely conspire to get the Magi off their astrological couches and into the saddle.

I hope that by now you have your own preferred theory. This is what I have found serious researchers into the Christmas Star to do, first carefully to select and then tenaciously to hold their pet theory. There is something about the Christmas Star that evokes passion in one. Presumably this passion was first felt by the Magi, and it sustained them through their long journey – and back home by a circuitous route. One’s preferred theory does not prove that astrology works or that the birth of Jesus was accompanied by astronomical phenomena. It does, I trust, help one realize that God uses our science and reasoning to draw us to himself. As we try to evoke the experience of those who first found the Babe of Bethlehem, may we too find the One who is the Light of the Universe, who comes to ‘shepherd my people’ into all Truth.