The Wise Men of the nativity followed a star to find Jesus. The term Wise Men is found scattered around the Bible to denote those with mystical knowledge. The alternative term used for them, Magi, is a term used for Persian Astrologers of that period. (Zoroastrian sect.)
The basic assumption is that they saw an event that would only occur once in a millennium or possibly longer. It is also assumed that the event was interpreted according to modern day astrology.
While there are undoubted differences in interpretation by astrologers, there is much common ground. Venus is associated with fertility and Jupiter with royalty. The royal constellation is/ was Leo and Regulus the royal star.
Whatever the Wise Men saw, it had to be exceptional and had to be within a context which would cause them to associate it with the birth of a king. Thus a Nova in Capricorn or Comet unrelated to any of the above seem unlikely candidates.