A fascinating analysis of just what was the star that led the wise men to Bethlehem is given at Bethlehemstar.net. I talked about this in the service this morning. I urge you to read the whole thing at the site, but here is my summary.
After Jesus was born, wise men, or Magi, from the east made their way to Judea. Being astronomers, they had read the stars and concluded that a new king had been born to the Jews. This is related in Matthew chapter 2.
No historian today claims that there nothing happened in the sky that corresponds to what the wise men saw. Just what it was has been a scientific quest for about 400 years, since Johannes Kepler developed the first mathematical description of how the heavens worked. Kepler, whose equations are still used by NASA and astronomers around the world, himself spent may laborious hours trying to calculate the position of the planets and stars above the ancient Near East in the year of Jesus’ presumed birth, 6 BC. But he found nothing.
Since Kepler, many others have suggested that the star Matthew describes might have been a comet or a supernova, but there are no records of such events at this time anywhere in the ancient world, especially in China, whose astronomers were detailed and meticulous record keepers.
Jesus was presumed to have been born in 6 BC based on a book by the ancient Jewish historian Josephus, whose book, Antiquities, says that Herod died in 4 BC. Since clearly Jesus was born in the time of Herod, Jesus had to have been born before 4 BC, a year or two before.
But in fact, Herod did not die until 1 BC. This date is in fact what Josephus wrote, and is stated in manuscripts of his book relate dated earlier than 1544. It was in 1544 that Antiquities was first set to the printing press. In that first edition, the typesetter erroneously set the wrong year of Herod’s birth, and this edition became the standard from which all subsequent editions were made, including the one Kepler used.
Computers today solve Kepler’s equations in a snap. And what astronomers now know is that in September, 3 BC, the planet Jupiter came into conjunction with the star Regulus. That is, when viewed from the earth, Jupiter and Regulus appeared to touch or come very close together.
Jupiter is the largest planet. The ancients called it the king of planets. Regulus was called by the Romans, Rex, Latin for king. In Persian its name was Sharu, which also meant king. To an ancient astronomer, for the king of planets and the king of stars to come together would have been weighted with portents. But Jupiter and Regulus did this not merely once, but three times over the course of the next year.
After appearing to touch Regulus, Jupiter’s path moved beyond. But after a few months, earth caught up with and passed Jupiter in its orbit. Jupiter then appeared to move backwards in the sky. This movement is called retrograde. All planets’ paths retrograde when seen from earth, that’s why they are called planets, which is Greek for “wanderer.” So Jupiter went back and touched Regulus again. Then the earth moved on and by September of 2 BC, Jupiter had retrograded once more and had touched Regulus a third time.
To astronomers as skilled as those of Babylonia heritage and learning, which the wise men almost certainly were, this three-time conjunction of the king of planets with the king of stars would have started them packing. But why did they decide that the Jews had anything to do with it?
All three conjunctions took place within the backdrop of the constellation Leo, the lion. The lion is the symbol of the Jewish tribe of Judah, which takes it name from a son of Jacob named Judah. In Genesis chapter 49, Jacob gives his son, Judah, the lion as his symbol and then dictates that only Judah’s descendants shall provide the rulers for subsequent generations. King David was a member of the tribe of Judah and so was Jesus’ father, Joseph, according to Matthew chapter one.
The wise men were obviously conversant with the relationship of lions with the tribe of Judah and Judah’s parentage of all the kings of Israel. The wise men may well have been (though probably weren't) Jews themselves, since a thriving Jewish colony remained in Iraq until a generation ago even though the Jews’ captivity in Babylon was ended in 538 BC. The kingly conjunctions of Jupiter and Regulus within the constellation of the lion were all the wise men needed to start heading toward the Roman province of Judea, which we know as Israel.
But what they did not know was just where the new king was to be born. So they stopped at the palace of the Roman vassal, King Herod, to inquire. Herod’s counselors quoted a prophecy from Micah that said the Messiah would be born in Bethlehem.
At Herod’s deceitful urging, the wise men went to Bethlehem, only five miles from Jerusalem. In the sky, Jupiter had just begun a third retrograde, this one, however, not to be followed by a conjunction. The thing about planetary retrogrades is this: just as a planet appears to reverse direction, it seems to stand still in the sky.
Here is what computers using Kepler’s equations show. Jupiter’s full stop for this retrograde took place on December 25, 2 BC. If you had been in Jerusalem on that evening, you would have seen the kingly planet Jupiter motionless in the sky almost due south, directly above Bethlehem.