Although the world continues to change and evolve at impressive speeds, there are some constants that will probably never cease to exist, surviving the ages and entire generations of humanity. The most obvious that can come to mind are the so-called "beliefs", religious or folkloristic in nature, which have survived for hundreds of years, and punctually present themselves at our door with their charm and their load of "customs".
If we talk about beliefs in this period we can not fail to mention Christmas: a holiday as famous as it is often underestimated, especially in the scientific field and within our competence.
Once the last nativity of this decade has arrived, we have to ask ourselves some questions, a bit with a festive attitude – as befits the period – and a little with our usual scrutinizing and curious eye. What can one say about Christmas in a scientific article, or at least try to be it?
Our journey begins now, precisely with this purpose: look for the lost science of Christmas.
Origins and early problems
Needless to say, how much Christmas is known, since it is without a doubt the most felt festive period by all humanity (not only Christian). Such an importance requires a really ancient past, that is, of the solid shoulders on which the modern conception of the party rests. In fact there is such antiquity, indeed it is so pronounced that even historians have had (and still have) problems in identifying its origin, traditionally associated with December 25 of the year 0, the day of the nativity of Jesus. however multiple complications in this statement and the most peculiar are essentially two. First of all we must remember that many centuries before the birth of Jesus it was customary to celebrate in this period, even even before the Romans. There was however a common thread to keep these customs cohesive: the astronomical position of the Sun and the "end" of a particular situation, which we will discuss shortly.
Another problem is that the year 0 – as someone may mistakenly think – does not exist nor is it contemplated by historians. Theoretically, the birth of Jesus was established between 7 and 4 BC, between 20 December and 6 January. Further studies then led to the choice of 25 as a fixed date also in accordance with the old pagan and pre-Christian holidays (in order to make the change less "drastic" when Christianity became the dominant religion).
It seems almost senseless that the Messiah was born "before Christ". In ancient times, when it was decided to count the years from the birth of Jesus, the concept of "zero"it had not even been conceived yet, and only after a thousand years did the eastern populations bring such novelty to the western world.
The common thread
As we said earlier there is a kind of common element between the pre-Christian Christmas and what we know today, and it is the Sun. The astronomical aspect of our festive period is the key not only to extracting a pinch of science from a totally religious celebration, but also to understand its meaning, going back to the dawn of civilization. We all know – good or bad – that the figure of Jesus is often united with the idea of new light and "infallible judgment".
This dualism with light closely follows the religious appellation of "Sol Invictus", that is, of the" never defeated Sun ", typical of the late Roman Empire, which happened to refer to divinities celebrated precisely in the period of our interest. The references are not lacking even in prehistoric times, and this is a clear sign of how everyone human beings, of all ages, have been conditioned by a single event, visible and incontrovertible: the winter solstice. Even in ancient times men had noticed, therefore, that the Sun in this period was at its lowest declination, and that the hours of light were increasingly reduced to the minimum day (which we today coincide with the 21st or December 22).
After this date the days returned to lengthen and therefore the rebirth of the Sun could be celebrated, that is, the rebirth of the invincible, undefeated celestial body. Today we also know that our star (due to the earth's inclination and the elliptical orbit) takes a few days to resume its normal course in the sky, giving the illusion that it is immobile for a while (solstice means precisely still sun ).
This is clearly visible in the apparent path that the Sun travels in the sky during the year, and which goes by the name of "analemma": a sort of 8, or elongated infinity, in which it is noted that the variation of the declination is slower in the area of the extremes, where the solstices fall precisely. The rebirth of light then seems to be more evident from December 25 onwards. This confirms that Christmas – in any way you want to understand it – is the feast of the Light and has profound roots in astronomy.
This obviously does not exclude any type of "faith", nor do we want to diminish the Christian sense of the holiday, but rather, we try to give it a further meaning, which may also affect the denialists of the faith or the "opposing bastians" by profession. Whether you are scrupulous men of science, or whole men of faith, Christmas can perhaps satisfy both appetites.
The Comet Star
Our search in the most unusual meanders of Christmas leads us to clash with another question, concerning the famous "Comet". Who among us has not attached one to the top of his tree, or perhaps placed on his crib? Usually beautiful sparkling, golden and with a beautiful tail is considered a symbol of guidance and hope, from the moment in which he is said to have guided the Three Kings to the home of the future king of the Jews in Bethlehem. But did it really exist? And if so, what would our three astrologers really see? The situation is extremely thorny and risks pulling us into areas that do not compete with us (there are disputes about the translations of the gospels, their interpretation and the changes that were made over the centuries), however we can instead venture that the people of that time certainly something she had seen, and probably had been deeply influenced by it. But let's go in order.
The name "comet star" suggests that something is wrong: either it is a star – fixed and point – or it is a comet (nebula and tails). Of this apparent dichotomy we can give two possible ones astronomical explanations: according to some calculations confirmed, also by Kepler, between the year 7 and 4 BC. it should have occurred a simultaneous alignment between Jupiter, Saturn and Mars, making them as one particularly bright celestial body.
It could also be the "guiding star" for further proof, namely that this alignment would have occurred in the Pisces constellation – in that period south / south-west of Jerusalem – and that is precisely in the direction that the Magi had to follow to reach Bethlehem. Another explanation, on the other hand, tends to support the thesis that it was a comet, but not in the period of the birth of Jesus.
Taking the studies and ephemeris done on Halley's comet it turned out that around the 12 BC a particularly brilliant passage should have occurred, which could have left scholars and cultured men of the time (including the evangelist Matthew) impressed to the point of inspiring them and convincing them to insert this phenomenon into their work – perhaps interpreting it as a prophetic symbol – this phenomenon. This situation was tangled up even more throughout history: for more than a thousand years classical sacred iconography had been used to represent the nativity with a point star, at least until Giotto he did not decide to give his contribution with a representation of the "adoration of the Magi" located in the Scrovegni Chapel, in Padua: he was in fact very impressed by the passage of the Halley's comet in 1301 and decided to change the depiction of the star, making it look like a meteor / comet. In short, Halley's comet has created quite a bustle!
Conclusions
Since then, it has never been possible to get to grips with the true nature of the Comet Star, much less that of Christmas in general, and perhaps it does not make all this sense to ask such a meticulous question about a holiday that tends mostly to a religious teaching.
It is also true that this curiosity led us to discover that once again theastronomy and the events of the cosmos they have profoundly influenced people's lives, causing them to insert their sense of wonder also in works that to us modern men may seem conceptually very distant.
This distance, between science and religion, between celestial bodies and earthly works, between divinity and men, it has become more severe with the course of time, and in this flow has risked and spent a lot in the name of one or the other "faction", sometimes even more than necessary. Fortunately, then comes a particular day of the year, which falls on December 25 and reminds us that it does not matter who believes in what, why any absolute can be shared infinitely even between the various extremes; it is enough to have judgment and conscientious soul.
Hoping that we have not affected anyone's sensitivity, we leave you wishing you simply to be moved by the love of knowledge, and that everyone can believe in what makes them happy, especially at Christmas. Best wishes!
