There are many puzzling details about the birth of Jesus, including the season, the year, the Star of Bethlehem, and the census of Augustus. Dates for the birth of Jesus often hover around the period from 7-4 B.C., although the birth could be several years later or possibly earlier. The Star of Bethlehem could be the bright celestial phenomenon shown in planetariums: 2 planets in conjunction, although the Gospel account of Matthew refers to a single star, not a conjunction.
Now after Jesus was born in Bethlehem in Judea in the days of Herod the king, magi from the east arrived in Jerusalem, saying, "Where is He who has been born King of the Jews? For we saw His star in the east, and have come to worship Him." (Matt. 2:1-1)A good case can be made for a comet. If the right one is picked, it can provide not only the year, but even the season for the birth of Jesus.
Winter ChristmasBy the 4th century, historians and theologians were celebrating a winter Christmas, but it wasn't until 525 that the year of Jesus' birth was fixed. That was when Dionysius Exiguus determined Jesus was born 8 days before a New Year's day in the year 1 A.D. The Gospels provide us with clues that Dionysius Exiguus was wrong.
Star of Bethlehem as CometAccording to Colin J. Humphreys in "The Star of Bethlehem -- a Comet in 5 BC -- and the Date of the Birth of Christ," from Quarterly Journal of the Royal Astronomical Society 32, 389-407 (1991), Jesus was probably born in 5 B.C., at the time the Chinese recorded a major, new, slow-moving comet -- a "sui-hsing," or star with a sweeping tail in the Capricorn region of the sky. This is the comet Humphreys believes was called the Star of Bethlehem.
MagiThe Star of Bethlehem was first mentioned in Matthew 2:1-12, which was probably written in about A.D. 80 and was based on earlier sources. Matthew tells of the magi coming from the East in response to the star. The magi, who were not called kings until the 6th century, were probably astronomer/astrologers from Mesopotamia or Persia where, because of a sizable Jewish population, they were acquainted with Jewish prophecy about a savior-king.
Humphreys says it was not uncommon for magi to visit kings. Magi accompanied King Tiridates of Armenia when he paid homage to Nero, but for magi to have visited Jesus, the astronomical sign must have been powerful. This is why Christmas displays at planetariums show the conjunction of Jupiter and Saturn in 7 B.C. Humphreys says this is a powerful astronomical sign, but it doesn't satisfy the Gospel description of the Star of Bethlehem as a single star or as one standing over the city, as described by contemporary historians. Humphreys says expressions like "'hung over' appear to be uniquely applied in ancient literature to describe a comet." If other evidence emerges showing conjunctions of planets were so described by the ancients, this argument would fail. A New York Times article (based on a National Geographic Channel show on the birth), What Jesus' Birth May Have Looked Like , cites John Mosley, from the Griffith Observatory, who believes it was a rare conjunction of Venus and Jupiter on June 17, 2 B.C.
"The two planets had merged into one single gleaming object, one giant star in the sky, in the direction of Jerusalem, as seen from Persia."This celestial phenomenon covers the problem of the appearance of a single star, but not the point about the star hovering.
The earliest interpretation of the star of Bethlehem comes from the third century Origen who thought it was a comet. Some who oppose the idea that it was a comet say comets were associated with calamities. Humphreys counters that calamity in war for one side means victory for the other. Besides, comets were also viewed as portents of change.