Birth of Christ: what is the real date of Christmas?

When was the first Christmas? On what date, historically, was Christ born? Although the Saviour’s birth has traditionally been celebrated on 25 December, the passing of the centuries has only created confusion, rather than additional clarity. This detail, of course, is peripheral to the main concerns of the Christian faith, but it is a legitimate study – even a challenge – for scholars to establish the facts connected with this major event in history.

Until recently, such efforts have not fared well. The situation was further obfuscated in the late 19^th century when the traditional dating derived from Dionysius Exiguus in the early Christian era was challenged by E. Schürer, who found from old astrological almanacs an eclipse of the moon, visible from Jerusalem in March of 4 BC and used this to place the death of Herod the Great in 4 BC, so that the birth of Christ would have been as early as 5-6 BC.

The scriptural authorities for the Nativity are Saints Matthew and Luke, but unfortunately they were seldom precise about dates, with one exception. It is frustrating for historians to read the scrupulous exactitude with which St Luke records the date when St John the Baptist began his ministry – important as the start of Christian evangelisation – contrasted with the lack of detail regarding the Nativity: “In the fifteenth year of the reign of Tiberius Caesar, Pontius Pilate being governor of Judea, and Herod being tetrarch of Galilee, and Philip his brother tetrarch of Iturea and the country of Trachonitis, and Lysanias tetrarch of Abilina, under the high priests Annas and Caiphas; the word of the Lord was made unto John, the son of Zachary, in the desert.” (St Luke, 3)

Such a mesh of cross-references is manna to the historian. Unfortunately, the lack of historical detail concerning the larger event, Christ’s birth, means that scholars have to construct their own network of evidence to discover the facts. Recently, two Italian academics, Dr Liberato De Caro, of the Institute of Crystallography of the National Research Council in Bari, and Professor Fernando La Greca, of the Department of Humanistic Studies at the University of Salerno, have conducted multidisciplinary research into the date of the Nativity, aided by modern scientific discoveries, and have reached a radically new, but highly credible, conclusion.

All research on this subject relies on several separate sources: scriptural and other chroniclers’ historical accounts; astronomical evidence, which is constantly improving with modern insights; and cultural practices in Jewish society of the period. A pivotal question for all researchers into the Nativity is to establish the date of the death of Herod the Great, because of his role in the biblical account: he must still have been alive after Jesus was born or he could not have ordered the Massacre of the Holy Innocents. Strangely, for such a prominent figure, the date of his death is obscure and controverted – or was until this new scholarly initiative by Italian academics.

In an interview with Edward Pentin for the National Catholic Register, a year ago, Dr De Caro distilled the essence of his team’s investigations. From an apparently casual scriptural verse, his team has progressed discoveries: “And his (Jesus’s) parents went every year to Jerusalem, at the solemn day of the pasch.” (St Luke 2:41) 

De Caro noted that there were three Jewish annual pilgrimages: one at Passover, one fifty days later at the (Jewish) Pentecost, and a third on the Feast of the Tabernacles, six months after Passover. The scriptural account relates that until the angel, at the Annunciation, told Mary that her cousin Elizabeth was six months pregnant, she was unaware of the fact. That means that she had not visited Jerusalem for months, or her close cousin would have told her the news. That implies that the Annunciation must have occurred late in the period between the Feast of the Tabernacles and the following Passover, the only lengthy, six or seven-month period between pilgrimages.

Since Passover was at the end of March or early April, and the Annunciation marked the conception of Christ, nine months after that would place his birth in December. To establish the year, De Caro and La Greca investigated the claim by historian Josephus Flavius that Herod the Great died after an eclipse of the moon that was visible from Jerusalem. Schürer had found such an eclipse in March of 4 BC, placing the Nativity back in 5 BC or even later. However, in the 1990s, astronomers had demonstrated that the eclipse of 4 BC could not have been visible in Jerusalem. A search of lunar eclipses visible in Jerusalem, using modern scientific information, puts the death of Herod later, in AD 2-3.

From this and accompanying research, De Caro and La Greca concluded that the Nativity occurred at the end of the year 1 BC. On the basis of that hypothesis, they extended their astronomical investigations to an obvious candidate: the Star of Bethlehem. On the assumption that it was not a miraculous image, but an actual astronomical occurrence, they considered the possibilities. They excluded comets, always seen as ill omens; fixed stars, because their relative distances do not change; and asteroids, as too dim to be seen by the naked eye. That left only planets.
They were looking for planetary conjunctions in which two planets would converge so as temporarily to look like a single celestial body, of exceptional brightness. This was because the evangelist related that the Magi said to Herod: “Where is he that is born King of the Jews? For we have seen his star in the East, and are come to adore him.” (St Matthew 2:1) This made it clear it was a single object. So, bearing in mind the age range of Herod’s victims, the researchers scanned the period from 2 BC to 1 AD.

In fact, the astronomer R. W. Sinnot had demonstrated that, on 17 June, 2 BC there was an exceptional Jupiter-Venus planetary conjunction when the two appeared to be a single celestial body. The conjoined planets became 200 times brighter than Regulus (“the Little King”), the brightest star in the constellation Leo and one of the brightest objects visible from earth. It must have been a spectacular sight and it is hardly surprising that it excited the Magi, Zoroastrian priest-astrologers from Persia. The two planets separated when Regulus disappeared below the horizon.

The academics extended their research, in a sweep of the entire period from 500 BC to the present day, and established that at no other time but in 2 BC were Jupiter and Venus visible to the naked eye, as if a single star, a phenomenon that lasted for two hours. Nor did any other planetary conjunctions fulfil the same conditions. They also noted a further phenomenon.

In 2 BC there was a stationary point of Jupiter’s apparent orbit which lasted for about a week, in the constellation Virgo, and began on 25 December. This followed an analogous stationary point of Jupiter in the constellation Leo, starting on 25 March. It thus linked the feast of the Annunciation, 25 March, with the feast of the Nativity, 25 December, in the year before the research strongly suggests Christ was born.

De Caro and La Greca believe that the arrival of the Magi in Jerusalem should not be placed immediately after the astronomical phenomena. That makes sense: preparations for a journey from Persia and the journey itself would have delayed the arrival of the Magi until long after. When they told Herod “We have seen his star,” they were referring to an event of the previous year, possibly 18 months earlier, which had motivated their journey.
The researchers believe the arrival of the Magi correlates most importantly with Herod’s slaughter of the infants of Bethlehem, dating it at the end of 1 BC, but after the Presentation of the child Jesus in the Temple, 40 days after his birth. De Caro points out that Joseph and Mary would not have taken the child to Jerusalem after the Magi had alerted Herod; in fact they fled into Egypt after the visit of the Magi.

The researchers have extended their investigations to the end of Jesus’s life, dating the crucifixion on Friday, 23 April, 34 AD, using calculations to establish distinctive features of that year, compatible with the Gospel accounts, but not relevant to the previous or subsequent years.

De Caro and La Greca do not claim their work is the last word: the science is never settled. But they have made a scholarly contribution to an interesting subject that fascinates millions of people. If our Saviour was born in December of 1 BC, quite possibly on the 25th of the month, and the Star of Bethlehem was a physical, recorded astronomical event, then many Church chroniclers are vindicated. The more detailed account of the search for the birth date and the less seasonal research into the date of the Crucifixion, for those who read Italian, is available here.

One of the most striking features of the De Caro/La Greca research is its multidisciplinary approach, using records two millennia old, paired with modern astronomical investigations, throwing additional light on the great event we are about to celebrate.