bttt
I wouldn’t rule out that a Jupiter-Saturn conjunction was some sort of sign to the wise men (who would have routinely used astrological guidance) but in our common understanding, the miraculous star of Bethlehem hovered over the site of the manger and the birth of Christ, whereas the planetary conjunction or any other astronomical event in the sunset sky like it would do what we’re going to see in December, set each night in the same area of the sky as the Sun had recently gone down, so it could do no more than suggest a course to the southwest, and our received story is that the wise men came from the east, so it would have only been the last few miles of their journey from Jerusalem to Bethlehem that had very much useful guidance from the planetary conjunction.
I looked this up in some reliable astronomical tables that I have handy here and the actual conjunction referenced by Kepler and the article’s author (he says it was in 7 B.C.) was in a similar aspect to the Sun, the earth having passed Jupiter and Saturn around the first of September but their closest apparition would have been more like that time of the year than later on the way we got to see it this year (in 2020, we passed Jupiter six days before we passed Saturn (July 14, 20), they had a heliocentric conjunction in October and now we’re in this close alignment ... in 7 B.C. according to these tables, we passed Jupiter and Saturn at almost the same time in mid-September, so that they would have appeared closest to us then, but a later timing may have produced a second close pass (probably later in the winter than December though).
That idea fits one concept I’ve read, that the actual nativity was in late winter, the season when shepherds would actually be out in the fields tending to the newborn lambs, rather than the winter solstice, a Roman feast that the early church decided would be a good basis for Christmas (so they built on its existing traditions).
That being the case, the “star of Bethlehem” may have been setting after sunset around February 15 to 28 of 6 B.C. after the autumn 7 B.C. conjunction.
It should also be noted if anyone’s checking their own sources, astronomers generally use the convention of a year zero between 1 B.C. and 1 A.D., and in my tables all of the above actually show up a year later, with the autumn conjunction listed for 6 B.C. and the February final stage in early 5 B.C. But historians generally avoid the use of the year zero and so most discussions you read (such as Herod dying in 4 B.C., etc) are in the time frame where no year zero exists.
Due to precession, the winter sky looked different in Roman times than it does today. Constellations used to rise a month earlier than we see them in our sky, this is why zodiac signs are generally speaking one month earlier than the Sun is nowadays in those signs. An example relevant to the winter sky would be Taurus, the sign applies to April 21 to May 21, but the sun is nowadays moving through Taurus from about May 21 to June 21, and at this time of year we see Taurus (leading Orion) in the due south by the middle of December. Romans would have seen it there in mid November. Going back another two thousand years, ancient Egyptians would have seen our winter sky in October (although they knew nothing of the names of our calendar months and had their own names). Going back to the late ice ages and the very ancient peoples at the dawn of history so to speak (around 8 to 10 thousand years before Christ), the current winter sky would have graced summer nights and the winter full moon would be seen against the rather barren portion of the sky where Jupiter and Saturn are located at the present time. A full cycle of this precession lasts 26,000 years.
As a result, the wise men would have been viewing their version of our planetary conjunction in a rather different part of the sky, not that far ahead of Taurus (with the Pleiades and Aldebaran out ahead of Orion). The two bright planets would have been prominent visitors to that familiar area of the night sky by the following two winters, Jupiter leading the way as it outpaced Saturn.
I also looked up the position of Mars (very bright in our current skies but nowhere near the Jupiter-Saturn conjunction). In the same winter (7 to 6 B.C. historical time, 6 to 5 B.C. astronomical time) Mars was in opposition in March, so it was basically a bit behind where it appears in this case, and would have been rising when the “star” was setting. And Venus in that winter was also a morning star as there had been an inferior conjunction in early November of the winter we’re discussing. That means it was visible in the evenings in the summer previous, went in front of the Sun and appeared in the morning skies of that winter. There was no triple conjunction of any bright planets in the winter being discussed.