If the star was just an ordinary celestial event, then it would have been visible to everyone; and Herod's own astrologers or interpreters would have seen it as early as the Wise Men did, and it would have come as no surprise.
But the text says that all Jerusalem was troubled when they heard that sages had arrived saying they had seen the star announcing the birth of the messiah.
So most likely none of the ordinary explanations fit.
While the astrologers ( or "wise men" ) may have calculated the time and place deemed "most auspicious" for the arrival or birth of a VIP, possibly to be interpreted as the Messiah, all of their calculations would not necessarilly tell them WHO that person was..
Only Where and When..
It then comes down to how many children were born in Bethlehem on that day/night when conditions were best..
How many were actually MALE..
How many male children actually survived the executions tradition says Herod ordered..
Lastly, how many male children fulfilling all the aforementioned prerequisites, and additionally, fullfilling all the other requirements listed by the prophets ( lineage, etc..) as well..
A remarkable set of "circumstances".. ( I won't say coincidence ) ..
"So most likely none of the ordinary explanations fit."
So aptly describing God.