Research Opens New Insights Into the Star of Bethlehem

“When Jesus was born in Bethlehem of Judea, in the days of King Herod, behold, magi from the east arrived in Jerusalem, saying, ‘Where is the newborn king of the Jews? We saw his star at its rising and have come to do him homage.’” (Matthew 2:1-2)

Byzantine depiction of the Magi in a sixth-century mosaic at the Basilica of Sant’Apollinare Nuovo in Ravenna, Italy.
Byzantine depiction of the Magi in a sixth-century mosaic at the Basilica of Sant’Apollinare Nuovo in Ravenna, Italy. (photo: Wikimedia Commons)

New research into origins of the Star of Bethlehem appears to confirm that a celestial body of great brightness did indeed exist at that time of Jesus’ birth and which guided the Magi to the manger. 

According to the leader of the research, Liberato De Caro, Ph.D., of the Institute of Crystallography of the National Research Council in Bari, Italy, the Star not only certainly existed but was most probably an exceptionally rare conjunction of Jupiter and Venus that shone 200 times more brightly than the brightest star seen from Earth.  

In this, the second in a series of interviews with the Register, De Caro explains his findings and how other factors appear to back up his theory. 

He also discusses a similar and rare phenomenon that will take place this year when a conjunction of Jupiter and Saturn will be visible in the night sky on Dec. 21. But although it is expected to be bright, De Caro explains how the intense brightness of the Star of Bethlehem would have appeared “100 times greater” than what will be seen on Dec. 21. 

 

Astronomical research claims to have found that there really was a Star of Bethlehem at the time of Jesus' birth. How true is this, what exactly could the star have been, and how would it have led to Christ in the manger?

There is a vast literature on the Stars of Bethlehem (Matthew 2:1) that would have illuminated the skies of the Holy Land at the time of Jesus’ birth. And it is a literature that first emerged in the early history of Christianity. Some of the first commentators of the Gospel according to Matthew rejected the hypothesis of a natural phenomenon and leaned towards divine intervention. 

It is enough to mention St. Augustine of Hippo who in the fourth-fifth century strongly condemned the astrological interpretation of the Star of Bethlehem in his theological disputes with the Manicheans. But others such as Origen in the third century claimed that it was a natural phenomenon, a new star similar to a comet or meteor, but a good omen. In fact, it’s important to remember that comets in antiquity were considered similar to particular atmospheric phenomena, linked to bad weather and bad omens. In any case, the miraculous interpretation of the Star of Bethlehem, compared to the explanation related to a natural phenomenon, prevailed until the early Middle Ages among Christian commentators. 

 

What led to astronomy being introduced as a means of explanation?

Only afterwards did hypotheses begin spreading that tried to explain Matthew’s passage (Matthew 2:1) using natural phenomena of astronomical nature.

In the mentality of the past, it was in fact common to expect the influence of the stars on the most important events of life and history. The belief was very widespread that, at the birth of each man, a star that would light up in the sky. But if we take the hypothesis that what Matthew reported is not only a literary topos [tradition or formula in literature] used for theological reasons, but that in the background narrative is an astronomical event that actually happened and was, by chance, concomitant with the birth of Jesus and that this coincidence was noted and annotated, then through astronomy we could have chronological information about his birth.

 

What does the astronomical theory entail?

The basic hypothesis is that Eastern astrologers, the Magi of Matthew’s Gospel, aware of Israeli messianic expectations in following their contacts with the Jews of the Diaspora, may have wanted to verify on the spot what they deduced by surveying the night skies, and would have headed precisely to the sole Judean kingdom of all Syria-Phoenicia and Palestine.

 

What kind of star could have shone so brightly at that time?

Given these premises, if we exclude: 1) comets, because they were considered harbingers of bad omens in antiquity; 2) fixed stars, even when they are strongly variable in brightness (novae, supernovae), because their relative distances do not change; 3) asteroids, because they are too dim to be easily visible to the naked eye; this leaves only planets able to be associated with the Star of Bethlehem. 

In particular, it is possible to associate the astronomical phenomenon of the Star of Bethlehem with planetary conjunctions which can be aligned well enough to seem to be a single celestial body, much brighter in the sky and mobile with respect to the fixed stars. The etymology of the word itself reveals that the ancients considered them “wandering stars.” In fact, planet in the Greek language indicates wandering, the moving of these celestial bodies in the night sky, once the background of the fixed stars was taken as a reference. 

In this regard, however, it should be noted that not all planetary conjunctions can be interpreted as the Star of Bethlehem. In fact, they do not always allow the planets to be near and close enough to each other to appear a single celestial body. And the text of Matthew 2:1 speaks of a single celestial body and not of more celestial bodies. This simple condition should exclude, logically speaking, most planetary conjunctions, since it’s very rare that two planets are so close to each other that they seem to form a single celestial body, as required by the narration of the evangelist Matthew. 

Ultimately, although in principle many different astronomical phenomena may have attracted the attention of the observatories of the night skies of 2,000 years ago, if we derive from Matthew 2:1 two simple properties that should characterize the Star of Bethlehem (assuming that it was a real astronomical phenomenon) — the first being its movement with respect to fixed stars and the second that it appeared as a single celestial body in the sky, then the possibilities of what the celestial body could have been are greatly reduced. 

 

Given these premises, what is the most plausible explanation for the Star of Bethlehem?

In light of our recent studies on the possible historicity of the birth of Jesus at the beginning of the winter of 1 B.C., in accordance with the date of the Christian Tradition and with the calculation made by Dionysius Exiguus in the sixth century, we have gone in search of an astronomical event that correlates with this dating, bound by the previous conditions of the movement and of a single celestial body or more celestial bodies aligned so well that seemed to be one. 

The detail of the age of two years of the Bethlehemite children slaughtered by Herod's soldiers (see Matthew 2:16), placed in correlation with the other information deduced from Matthew's narration — “then Herod called the Magi secretly and found out from them the exact time the star had appeared” (Matthew 2:7) — could contain a chronological indication about the time interval relevant to the search for possible astronomical phenomena correlated with the birth of Jesus. If it happened at the end of 1 B.C., as discussed above, the astronomical research should be placed in a time period of more or less one year around that date, that is from 2 B.C. to 1 AD. 

In fact, in 2 B.C., June 17 to be precise, there was an exceptional Jupiter-Venus planetary conjunction which were so close to each other to appear as a single celestial body, as demonstrated for the first time by the astronomer R.W. Sinnot. 

Strengthening each other’s luminosity, the apparent magnitude of the two planets in perfect conjunction became about 200 times brighter than Regulus, that is, the brightest star in the constellation Leo [and among the brightest stars visible from Earth]. The etymology of Regulus means “little king”. The two planets became visible again separately as soon as Regulus disappeared on the horizon, as if to indicate that the “little King” had left the sky to descend to earth (birth).

 

How extraordinary was such an astronomical event?

To understand how rare this unusual behavior of Venus and Jupiter is, we have searched all the conjunctions of “planets with characteristics similar to those of June 17, 2 B.C., visible from Palestine and neighboring regions. Extending our astronomical analysis over a time span of more than 2,500 years, from 500 B.C. to today, we have come to the surprising observation that only in 2 B.C. were Jupiter and Venus visible to the naked eye as if they were a single star, for about two hours, while before and after that, they were still visible but separated from each other. 

There is not only the distance between the planets as a condition to be met. For example, it is important also their distance from the sun, which must be set sufficiently before the planets, and the visibility of the conjunction from Palestine and surrounding regions. It is, therefore, a very rare astronomical event. 

To give you a more quantitative idea, the angular diameter of the full moon in the sky is about half a degree. When two objects, seen by an observer, have an angular distance less than 1/60 degrees, they appear as a single object. The minimum angular distance between Venus and Jupiter, on the June 17, 2 B.C., was smaller than this limit — about “half” of this limit — and the two planets appeared in the sky as a single celestial body. 

Instead, on Dec. 21 this year, Saturn and Jupiter will be at an angular distance of about 1/10 (of one) degree, about 10 times larger than that between Venus and Jupiter, in June of 2 B.C. Thus, even if it is a rare conjunction, Saturn and Jupiter should not appear as a single celestial body. Moreover, Venus, on June 17, 2 B.C., had an apparent magnitude — a brightness — about 100 times greater than Saturn will have on Dec. 21. 

All these numbers confirm how rare was a planetary conjunction such as that between Jupiter and Venus of June 17, 2 B.C.

Another interesting astronomical element to highlight is that in 2 B.C. there was a stationary point of Jupiter's apparent orbit, which lasted about a week, which occurred in the constellation of Virgo, starting from December 25 of that year. Recall that at a stationary point the apparent motion of the planets is reversed and, consequently, they appear as if standing in the sky, with respect to the fixed stars, for a certain number of days. 

An analogous stationary point of the apparent motion of the planet Jupiter in the constellation of Leo took place starting from March 25, 2 B.C. So, similar to what would happen at the end of December of the same year, even at the end of March it seemed as if the planet had stopped for about a week. We observe that the two stationary points of Jupiter's apparent motion are temporally separated by exactly nine months, that is precisely the gestation time corresponding to a pregnancy. 

Combining these temporal coincidences of the stationing points of Jupiter with the exceptional conjunction that took place on June 17 of this planet with Venus, we believe there is sufficient data to associate everything with the Star of Bethlehem of Matthew 2. 

 

When would the Magi arrive in Judea?

If the arrival of the Magi in Judea was an historical event, it should not be placed immediately after the astronomical phenomenon, since everything should also be correlated with the reference to the children of Bethlehem aged under two who were killed by Herod the Great, as reported by the evangelist Matthew. 

In other words, the Magi arrived in Judea about two years after having seen in the sky the star announcing the birth of a king (the age of children killed by Herod was up to two years). Therefore, all these astronomical phenomena concerning the Star happened in 2 B.C.

Since these astronomical phenomena occurred that year, it is possible to place the arrival of the Magi in Jerusalem in agreement with the birth of Jesus in the early winter of 1 BC, but after the Jewish ritual of offering the firstborn male to God, in the Temple, 40 days after his birth. In fact, Mary and Joseph would have been afraid to go to Jerusalem, if Herod the Great had already known from the Magi about the birth of the Messiah.

 

What final conclusions can we draw from your findings?

In short, witnessing such a unique astronomical phenomenon should have left an historical impression on ancient astronomers seeing as they were eyewitnesses of such a rare event. And it is very likely that it was associated with the birth of a king because Jupiter was considered the king’s star. 

For people today and for astronomy, the Star of Bethlehem is treated as a fortuitous correlation between a celestial phenomenon and a historical event. 

But for those who lived 2,000 years ago, for whom the sky always told in advance what would happen on Earth, this type of association between a celestial event and history was completely normal. And this is what could have happened in 2 B.C. when the Jupiter-Venus conjunction of June 17 was later read retrospectively in light of historical events, in connection with the birth of Jesus that occurred at the beginning of winter 1 B.C.

For more information: 

F. La Greca and L. De Caro, Insights on the birth of Jesus in 1 B.C. and the date of the crucifixion in 34, Annales Theologici 34 (2020), 13-58: ifpress-ecommerce.com/ojs/index.php/ATh/article/view/450