Dating the Birth of Jesus

When Jesus was born seems to have an obvious answer since our dating system is based on the idea that Jesus was born between the eras we call B.C. and A.D. Christians also celebrate the birth of Jesus near the Winter Solstice, on Christmas, or the Epiphany (January 6). However, the date of Jesus' birth is not explicitly stated in the Gospels. Assuming Jesus was an historical figure, the Star of Bethlehem is one of the main tools used to calculate when he was born.

The Star of Bethlehem

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 Christmas

By 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 Comet

According 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, 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.

The Three Magi

The Star of Bethlehem was first mentioned in Matthew 2:1-12, which was likely written around 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.

Determining Which Comet

Assuming the Star of Bethlehem was a comet, there were 3 possible years, 12, 5, and 4 B.C. By using the one relevant, fixed date in the Gospels, the 15th year of Tiberius Caesar (A.D. 28/29), at which time Jesus is described as "about 30," 12 B.C. is too early for the date of Jesus' birth since by A.D. 28 he would have been 40. Herod the Great is generally assumed to have died in the spring of 4 B.C., but was alive when Jesus was born, which makes 4 B.C. unlikely, although possible. In addition, the Chinese do not describe the comet of 4 B.C. This leaves 5 B.C., the date Humphreys prefers. The Chinese say the comet appeared between March 9 and April 6 and lasted over 70 days.

The Problematic Census

Humphreys deals with most of the problems associated with the 5 B.C. dating, including one not strictly astronomical. He says the best-known censuses of Augustus occurred in 28 and 8 B.C., and A.D. 14. These were for Roman citizens only. Josephus and Luke 2:2 refer to another census, at which the Jews of the area would have been taxed. This census was under Quirinius, governor of Syria, but it was later than the probable birth date of Jesus. Humphreys says this problem can be answered by assuming the census was not for taxation but for pledging allegiance to the Caesar, which Josephus (Ant. XVII.ii.4) dates to a year before the death of King Herod. In addition, it is possible to translate the passage of Luke to say it happened before the governor was Quirinius.

The Date of Jesus' Birth

From all these figures, Humphreys deduces that Jesus was born between March 9 and May 4, 5 B.C. This period has the added virtue of including the year's Passover, a most propitious time for the birth of a Messiah.