An alignment of multiple planets and bright stars in the night sky might be the best explanation.
Indeed, it had to be something the Jews were NOT looking for but which would have of interest to Magi.
Who sent that “star” to lead the astrologers?
Religious leaders commonly
teach that God sent the “star.”
Did he really?
Remember, the “star” did not first lead those astrologers to Bethlehem.
Rather, it led them to King Herod in Jerusalem.
They revealed Jesus’ existence to that jealous and powerful murderer and even gave him strong reason for hating the child who was to become “king of the Jews.” (Matthew 2:2)
Herod told them to report back to him on the precise location of this child,
Claiming that he wanted to honor it as well.
The “star” then led the astrologers to Joseph and Mary.
So the astrologers were on a course that would have doomed the young child had God not intervened.
Happily, he did intervene. So enraged was Herod when the astrologers did not report back to him that he ordered all the male children two years of age and younger in and around Bethlehem to be killed.—Matthew 2:16.
Another “myth” about this story is “The Three Wise Men!”
There was nowhere in the scriptures that called them Wise Men.
In the original Greek, the Bible calls them neither kings nor wise men.
They were magi, or astrologers.
They were evidently practicers of the
pagan art of divination based on the stars.
The Bible record reveals neither the names nor the number of these visitors.
No ancient astrologer worth his salt would have referred to a conjunction as a star. They certainly knew to the day when Jupiter and Saturn would conjoin. They’d have found it noteworthy but not arduous journey worthy.
The prime suspect is an object, possibly a nova or supernova, that was observed by Chinese astrologers in 5 BC. It was seen in early March and lasted more than 70 days. There’s a page here: http://www.observadores-cometas.com/cometas/Star/Visibility_Star.htm
which gets rather technical sometimes but it’s probably the best exposition online. Short version, the object was observed somewhere in the vicinity of the horns of Capricorn, and the constellation Aquila. The article doesn’t go far into the esoteric significance of al-Gedi, in the horns of Capricorn, but in ancient times this was regarded as the sacrifice, the atonement. Which may have meant something to the Magi.
As for the Jupiter-Saturn conjunction nearest that time, they conjoined in Pisces in 7 BC if I’m not mistaken...and visually they weren’t close enough to appear as a single bright object.