I was brought up to believe that Christ was born on September 11th, either
3 BC or 4 BC (I can’t remember the year). Supposedly all nine planets
were lined up in a straight line on that day. Does this claim have any
validity?

The fact is that no one knows the exact date of the birth of
Jesus. Based on the context of the gospel accounts, we know that it was
not in December, because the shepherds were out in their fields. We also
know that it certainly was before 3BC because Herod died in 4BC and
Matthew records his attempts to kill the baby Jesus. For these reasons,
the date September 11th 4BC is a possible date, but there is no proof of
this date. I am guessing that whoever came up with the date you quote is
trying to explain the star of Bethlehem which the magi from the East
followed to find Jesus. I cannot absolutely rule out this possibility,
but I doubt it very much. The magi of Babylon were experts at astronomy
and would not have perceived of this as a miraculous event; causing them
to search for a savior in the West. To be honest, I have no natural
explanation for the Star of Bethlehem. It remains a mystery to me.
However, I personally doubt the explanation of an alignment of the planets.

Bottom line, anyone who tells you they know the exact date of
the birth of Jesus is almost certainly not right. I would be very
skeptical of any conclusions coming from a person who claims to know the
exact date of the birth of Jesus. Besides, I cannot think of any
particular reason why knowing the exact date of his birth would be
particularly significant to the Christian religion. If it had been
important, God would presumably given some sort of clear indication in
scripture.

John Oakes