Perhaps...
A recent report that the "star of Bethlehem" was caused by a conjunction of the Moon and Jupiter very close in the sky, something that recurs only rarely.
From this, an astronomer calculated the birthdate of Jesus at 7 BC, if the "star" was the pattern he noticed.
I can't remember the URL right now :-(
(personally, I think the ancients would have described the closeness of the Moon and a planet as just that)