Look to the skies: rare chance to see candidate for Star of Bethlehem?
Right on the solstice, a ‘great conjunction’ of Jupiter and Saturn will occur when the two planets converge shortly after sunset Australia time tonight, Monday 21 December. They will appear almost as one object, being at one point only a fraction of a degree apart. A conjunction of Jupiter and Saturn occurs around once every 20 years, but this is the closest they have been together since 1623, says Associate Professor David Coward from the University of Western Australia’s School of Physics, Mathematics and Computing. Although the event is not scientifically important, the spectacle will offer viewers a real treat to admire the beauty of this rare alignment.
Historical and Biblical Significance
It is just possible that a similar conjunction back in 7BC was responsible for a bright ‘star’ in the the sky which may have sparked the biblical legend of a star marking the birth of Jesus — if this story has any basis at all in historical fact. The shining star that heralded the birth of Jesus is mentioned only in the Gospel of Matthew, and the text is not very scientifically informative, making it difficult to identify the star as a celestial event. The uncertainty of an accurate date for the birth of Jesus further complicates an identification.
That hasn’t stopped scientists offering a wealth of explanations over the years for what led the three wise men to Bethlehem. Suggestions for the celestial event have included:
- A comet
- A nova or a supernova
- The planet of Venus
- A powerful shooting star
- A constellation of bright planets combining to emit bright light
The Most Likely Explanations
According to modern astronomers, the last of these is the most likely explanation. Particularly notable in this regard is the triple conjunction that occurred between Jupiter and Saturn in 7 BC. Three times within seven months the two planets passed closely by each other, an event which happens only once every 900 years. The two bright planets merging in the sky might well have made such an impression that the light could have been considered a sign from God. The timing of the celestial events is consistent with historical estimates of the year in which Jesus was born, placing this between 4 BC and 8 BC.
Another candidate for the bright star above Bethlehem is the conjunction between Jupiter and Venus in June of the year 2 BC. Observed from Earth, the two bright planets would have merged.
The following table summarizes the primary celestial candidates mentioned by scientists:
| Candidate Event | Estimated Date | Key Characteristics |
|---|---|---|
| Triple conjunction (Jupiter and Saturn) | 7 BC | Happens only once every 900 years; planets passed closely three times in seven months. |
| Conjunction (Jupiter and Venus) | June 2 BC | The two bright planets would have merged as observed from Earth. |
| Other possibilities | Variable | A comet, a nova, a supernova, or a powerful shooting star. |
Future Encounters
If you miss the current event, mark your diary for 31 October 2040, or better still for 15 March 2080, when the next extra-close encounter between the two planets will take place.