“You can't follow a star from Baghdad to Jerusalem to Bethlehem. Stars don't do that”
An event that supposedly occurred thousands of years ago is suspected to be a planetary conjunction, rather than a star, that guided three wise men to a stable
We all know the story. Approximately two millennia ago, three Magi – or wise men – followed the Star of Bethlehem to Jerusalem. After consulting with King Herod of Judea, they locate the birth of a baby boy in the little town of Bethlehem, claimed to be the baby Jesus. Whether such an event really happened in history is difficult to prove, but if it did, what might that 'star' have been?
This is a question scholars have long pondered, not just from a religious perspective, but from a scientific one too. Plenty of theories have been proposed, from an astronomical event to an astrological horoscope, and thanks to our modern knowledge of astronomy, we now think we're getting closer to an answer.
“If what is in the New Testament is a historical account of something, then that historical account requires an explanation,” David Weintraub, Professor of Physics and Astronomy at Vanderbilt University in Tennessee tells All About Space. “As an astronomer, you want an astronomical explanation.”
And that is exactly what astronomers have tried to do over the years. The Star of Bethlehem only appears in one book of The Bible, the Gospel of Matthew. While this means the amount of information on the event is limited, we do gain a few tidbits from The Bible, and piecing these together with our knowledge of science gets us close to an answer.
We know that Halley's Comet was visible in the sky in 12 BCE. As the Magi trekked towards Jerusalem and on to Bethlehem, it seems unlikely they were following a comet, because its position would have changed as the Earth rotated. It would not have led them in a single direction. What's more, in the ancient world, comets were regarded as bad omens, indictaing death, disaster, doom or even disease.
“For Christmas cards, it makes a nice picture having a comet and a tail,” Grant Mathews, Professor of Theoretical Astrophysics and Cosmology at the University of Notre Dame in Indiana, tells All About
Space. “But in those days comets up in the sky were usually a harbinger of impending disaster.”
For similar reasons, we can rule out various novae and supernovae around 5 BCE. Thanks to Chinese astronomers, we know that several such exploding stars occurred but these events would not point in one direction in the sky. Had the Magi followed one, they would essentially have walked in a circle. Furthermore, star death would have resulted in a detectable supernova remnant, but astronomers have not found anything that might date back to this time. “You can't follow a star from Baghdad to Jerusalem to Bethlehem,” says Weintraub. “Stars don't do that. They rise and set, and they don't sit in the sky.”
Such an event would surely have been seen by others at the time, too. Although novae are reportedly quite rare, you'd still expect some more
“If what is in the New Testament is a historical account of something, then that requires an explanation”
David Weintraub
historical accounts of a large, bright event in the sky, but aside from the Gospel of Matthew there isn't really anything. The same argument, if you needed it, seems to rule out this being a miracle. Had the Angel of the Lord come down, wouldn't others have seen it?
Other theories suggest a hypernova in the Andromeda Galaxy as the cause. Although it is possible to see the galaxy, it isn't possible to see a star going supernova and exploding within it, even with the help of a telescope.
This leads us to one of two possibilities. The first is that the Magi were making an astrological interpretation of the sky. Due to a particular alignment of planets and stars, they may have read a hidden meaning among the stars, leading them to King Herod. The fact that they needed to ask Herod for directions when they arrived suggests they were not being led to their final destination by a single bright object.
The other, more astronomical, explanation is that there was indeed a bright object in the sky – a conjunction between planets and stars. A conjunction occurs when two celestial bodies appear to meet in the night sky from our location
on Earth, such as two planets passing close to other, and this can result in them appearing especially bright. These events can continue every night in a similar location for days or weeks. If one were to follow the moment of conjunction, it's possible they could be led in a particular direction.
A important book by former Rutgers University astronomer Michael Molnar in 1999, called The Star of Bethlehem, first suggested one of these theories might be correct. If the conjunction idea is true, though, and this historical event did really happen, then there are a number of different alignments that could be the culprit.
Perhaps the most promising, and the one favoured by Mathews, is an alignment of Jupiter, Saturn, the Moon and the Sun in the constellation of Aries on 17 April, 6 BCE. It seems to line up pretty well with the story. For one thing, the New Testament notes they saw the star rising, suggesting it was a morning star – which this conjunction was.
They also reportedly lost sight of the star, before seeing it come to rest in the place where the child was. This could have been the result of the retrograde motion of Jupiter, which means that it appears to change direction in the night sky as Earth's orbit overtakes it. “Normally, planets move eastward if you're following them in the sky,” says Mathews, “but when they go through retrograde motion, they turn around and go in the direction that the stars rise and set at night [the west].”
Two other conjunctions around a similar time also look promising. One is the meeting of Jupiter, Venus and the star Regulus in the constellation of Leo on 17 June, 2 BCE. To most people, the two planets would appear as a single 'star', brighter than Venus and Jupiter individually. Another is in 6 BCE, between, Jupiter, Saturn and Mars in Pisces, but, neither of these as closely match the description in the New Testament as the conjunction on 17 April – coincidentally just before Passover.
There is the chance, of course, that they weren't following a literal star at all. They may instead have been reading signs from the stars themselves, using astrology to pinpoint the location of the Messiah's birth. Astrology was widely used at the time, and with the Magi coming from Babylon, its plausible that they were astrologers. Jupiter's display could have been of great significance here too, as astrology associated the planet Jupiter with royalty, so the Moon passing it in Aries on 17 April 6 BCE could have heralded the birth of Christ.
“Modern astronomers don't put any credence in astrology, but 'modern' is important in this context,” says Weintraub. “What's important is what people thought 2,000-years ago. Astrology was a big deal back then. The explanation I have found that makes the most sense is that it was astrological.”
It's unlikely we will ever know for sure whether this event actually happened, or what caused it, unless we make an unexpected archaeological finding. But it's a question that comes up year after year, and while we haven't got a concrete answer, we can certainly rule out a few ideas at the very least. “Nothing in science is ever case closed, nor is it in history,” says Mathews. “We may never know if the Star of Bethlehem was a conjunction, astrological event or a fable to advance Christianity. Maybe it was simply a miracle."
“In those days comets up in the sky were usually a harbinger of impending disaster” Grant Mathews