A PASSION FOR
The Sky at Night presenter considers the candidates for the Biblical Star of Bethlehem
Ilove Christmas with all of its traditions: the lights, the carols and, of course, the star. It is only mentioned in one of the gospels – Matthew – yet the Star of Bethlehem has become a staple for all of us. But was it real and if so what could it have been?
The timing of the Nativity is not spelt out in detail in the Bible, but reference is made to the Magi meeting King Herod. He is thought to have died between 4 BC and 1 BC, so Jesus must have been born before this. Most scholars set the timescale between 4 BC and 8 BC.
The Magi were considered to be wise men and it’s also likely that they would have been familiar with the night sky, observing cosmic events and interpreting their meanings. The star that they are said to have followed may have been a comet, a possible contender; these bodies can be seen in the sky for months at a time, giving the Magi plenty of time to follow it, and they can also be very bright. On top of that, Chinese astronomers reported two comets in this period, one in 4 BC and another in 5 BC. It seems unlikely that the Magi would have considered this to be good news though: comets were usually seen to be harbingers of doom.
Planets can sometimes be mistaken for stars, and research has shown that around 7 BC there was a conjunction between Saturn and Jupiter. This rare event would have made for a spectacular sight, but I think that the Magi would be aware of this and may have even anticipated its occurrence. Nevertheless they may have still taken it as an omen of something fortuitous happening imminently.
Explosive contenders
A more likely candidate for the star is a nova. This is a binary star pairing, where a dense white dwarf steals matter from its companion star until it reaches a critical mass. Then its outer shell ignites and burns brightly: all of a sudden it goes from being invisible to the naked eye to one of the brighter objects in the night sky. But once the matter in the shell is exhausted the star fades to obscurity, only to start the whole process again.
In term of a star suddenly appearing in the night sky and being visible for a few months, a nova makes a good candidate for the star. Then again so does its big brother, the supernova.
A supernova is my favourite explanation. Brighter than a nova, this is the death throes of a massive star. It occurs when the balance between the star’s inwardly pulling gravity and its outwardly pushing core fusion energy is disrupted, as the fuel for fusion runs out. When this happens gravity takes over, shrinking to star until its core implodes and a colossal nuclear explosion ensues. For a few weeks this is the brightest thing in the night sky, shining brighter than all the other stars in the Galaxy combined.
The sheer scale of a supernova makes it appealing as the Star of Bethlehem but in truth we may never really know what it was. It still acts as a symbol for many and brings the hope for peace on Earth, and to me that is a great sentiment, no matter what time of year.