The Star of the East, along with Ezekial’s Wheel, over the past few decades has been great grist for the UFO/Ancient Alien crowd- at least the ones that aren’t avowed atheists.
We can only conclude so much from the ancient sources.
But certainly for three wise and wealthy men from the East- presumably Parthia- to pack up and travel into Herod’s world along with their entourages because of the formation they saw in the sky- well, it had to be formidable and once-in-a-lifetime event.
Halley’s Comet would be all of that.
Not only would Halley’s Comet be by far the brightest object in the sky, and easily seen during the daytime, but it’s trajectory ran COUNTER to the planets.
A VERY remarkable event.
No reason to downplay it.
Sure, a comet has the advantage of ‘moving’ especially when compared to other candidates, and no star moves from north to southwest (the direction from Jerusalem to Bethlehem). But note the description of the star: one moment it “was going ahead” of the Magi (the imperfect tense in the Greek implies an ongoing movement) toward Bethlehem when all of a sudden “it came and stood” over the place where the Infant was. Comets move, sure, but they do not grind to a halt all of a sudden AFAIK, especially over a precise location, as the text seems to imply.
It also fails to take into account that the star likely disappeared before the Magi saw it again en route to Bethlehem.
At least we have no indication that the star was visible when the Magi arrived at Jerusalem; on the contrary, Herod and the Jerusalemites seem to have no knowledge of the star. (Herod was “troubled” by the Magi’s words - “When Herod the king
heard this” - not by the sight of any star.) In other words, the star was not continually in the sky: it appeared, then disappeared for a period of time before reappearing again. Not exactly the thing you have with comets, particularly big bright ones, as you admit.
If we go by a strict reading of the text, the star “went before them till it came to rest over the place where the child was.” (Or as some manuscripts read, “came to rest over the child.”) Going by the narrative flow, the Magi (and the reader) would have already known that the baby they were looking for was in Bethlehem. The only remaining question was
where in Bethlehem the child was lying, and that’s when the star came in. It’s not so much that the star guided them to Bethlehem, but to a certain house within Bethlehem. (So no case of mistaken identity I guess,
as Monty Python would imply. 
)
I think the Fathers had the best understanding of the passage here: this was a miracle and no ordinary star or heavenly body. So what if there are people who link these and Ezekiel’s chariot with alien spacecraft? Dead men rising again, the sea splitting in two or the angels of God appearing to people is already out of the ordinary. Why should a ‘star’ moving out of course be any less?
