The star that shown above Bethlehem on Baby Jesus is a good example of how holiness is the marriage of the natural and the spiritual. With God being born on earth a great conjunction was being restored between heaven and earth; God was entering the natural. Because of this conjunction by the law of correspondences it could not be otherwise than that a light would shine in both. The natural world is connected to the spiritual by correspondences in all particulars; it is the foundation of it, and what is in the spiritual world must have a corresponding foundation in the natural. In the spiritual world the Lord always appears to the angels as the spiritual sun, so in the glory of this newly founded conjunction light from a star was visible even in the natural for a time. I would conjecture that there may have been some kind of supernova in a star far away that burned so bright that it could be seen shinning in the daylight; the supernova would be a natural correspondence with the spiritual event. Or, I suppose it is possible that the Lord allowed the spiritual sun to be seen for a time, similar to the way He allowed the shepherds and many others to see light from heaven for a time. Either way it is Holy, and took place by the providence of God in heaven.
In the moment of union there is revelation and inspiration and the light burns brighter. The angels of heaven were rejoicing at this new hope for the restoration of good on earth; their great love, desire and work is for the salvation of others; the light from the star is only the tip of the iceburg seen on earth that corresponds to the light and rejoicing in heaven. The divine itself was entering the natural world – the greatest event in history – and the star was the manifestation of the greatness of this brightly burning union. The gospels give us an idea of how the rejoicing of heaven poured over into the natural world: at the time Jesus was born shepherds keeping watch in a field were suddenly immersed in light from heaven; and they received the joyous message from angels that a savior was born.