Like many children, I was brought up with the magical story of The Star of Bethlehem that led the Three Wise Men to the baby Jesus. The same story that captivated generations of children has kept astronomers guessing as to the nature of the mysterious star -- if it was indeed a 'star.' Reliable and accurate observational and historical records are limited, so instead scientists have turned to computer simulations of the sky during that time to investigate the possible celestial suspects. There are a number of possible explanations that have been mulled over the years, but four of them seem most likely.
Image: Illustration of Three Wise Men Viewing Star of Bethlehem by W.L. Taylor
The three wise men referenced in the Biblical story are widely accepted to have been top-notch astrologers. In astrology speak, Jupiter is the King planet and around the birth of Jesus, it completed a retrograde loop (backward motion among the stars) near to Regulus in Leo, the King star! The interaction in the sky between these two objects would have been a sign to the astrologers of the birth of a new King, possibly explaining The Star of Bethlehem.
Another possible explanation comes from the rather ethereal comets that wander through our solar system. Comets occasionally produce a stunning show in our night sky with the tail of the comet giving an arrow-like appearance. There was one such bright comet in Capricorn in around 5 B.C. Calculations have shown that it would have appeared low in the sky from the area surrounding Jerusalem, with its tail likely pointing almost vertically.
One of the more striking naked-eye events in the night sky is an alignment of two or more of the brighter planets. There are a number of conjunctions that might have been interpreted as an event that was pretty significant. Of particular interest might have been a rare conjunction between Jupiter and Saturn.
Image: Jupiter, Venus and the moon over the ESO’s Very Large Telescope (VLT) observatory in Chile.
The sighting of a new star, or 'nova', was recorded by Far Eastern astronomers in 4 B.C. in the constellation Aquila. This stellar outburst was visible to the naked eye and would have been visible from Jerusalem. Seeing a new star in the sky could also have led the Wise Men to interpret the birth of a King.
We may never know whether the star of Bethlehem was a planetary event, a comet, a nova or indeed simply just a story to inspire and give hope. If it did exist then it is a fascinating insight into the relationship of society and the night sky thousands of years ago.
Image: The recurring nova of RS Ophiuchi.