It is an age-old mystery that we wonder about at this time of year. Was the Star of Bethlehem a miracle, a myth or a real astronomical event?

Ruth Campbell talks to one North Yorkshire astronomer who believes he has the answer.

BY now, many of us will have received Christmas cards featuring pictures of the three wise men following the Star of Bethlehem. We will have sung carols about the star of wonder and attended Nativity plays where a golden cut-out star hangs above the stable where the infant Jesus lies.

The story of the star has been told for thousands of years but, according to one North Yorkshire astronomer, it is only in recent years that we have been able to truly understand exactly what it might have been.

For centuries, scientists and historians have grappled with hand-written charts, complex mathematical equations and biblical writings in an attempt to discover its origin. But modern computer software means it is now easy for astronomers to calculate exactly what was happening in the sky thousands of years ago, at the click of a button.

Martin Lunn, who has been curator of astronomy at the Yorkshire Museum for 12 years, started researching the story of the star five years ago, as a response to the large number of questions members of the public asked about it at this time of year.

“Was it a miracle, a myth or a real astronomical event? I wanted to look at all possibilities,”

he says. “But as a scientist, I have to deal in facts.”

One hard fact that Mr Lunn lays bare – and, please look away now if you are of a particularly sensitive nature or under the age of 12 – is that Christmas is not actually on December 25.

Historians and scientists are agreed that Christ’s birth date is more likely to be in March.

Mr Lunn, a former railway worker who took a degree in astrophysics more than 25 years ago, points out that December 25 is close to the winter solstice festival.

“The Christian faith took over pagan festivals and adopted them, with Christmas Day first being celebrated on December 25 in 336AD,” he says.

“Historical records suggest King Herod died when the baby Jesus was a year old, shortly after a lunar eclipse. Computer projections show a lunar eclipse over Jericho in March 4BC, suggesting the baby Jesus was born in March 5BC.” And reports of lambs in the fields at the time also point to spring.

As if this wasn’t bad enough, Mr Lunn explains that, thanks to a number of basic calculation errors made by the monk Dionysius when he drew up our Christian calendar, Jesus could not have been born in the year zero because our dates are all at least five years out.

“He was, more likely, born five years before that, in 5BC,” says Mr Lunn. It was only once scientists had settled on a more accurate time line, he explains, that they could examine exactly what was happening in the night sky in Bethlehem around this time.

According to Matthew’s gospel, the moving star is described as appearing to the wise men in the east, eventually stopping over Bethlehem: “They went on their way, and the star they had seen in the east went ahead of them until it stopped over the place where the child was.”

The men, says Mr Lunn, were probably astronomers, rather than kings: “They were only referred to as ‘kings’ from the 6th Century onwards.

But three kings certainly wouldn’t have been on their own, without back-up or support.

These were people familiar with the night sky and the world around them.”

BUT what, exactly, did they see? Mr Lunn says there are a number of options. Astronomy was a revered profession at that time, and everything that was happening in the night sky was being recorded: “We are looking for something pretty special that appeared in the night sky around 5BC. It would have to be something out of the ordinary to stand out.”

One common assumption is that the star was actually Halley’s Comet. The Italian painter Giotto di Bondone even created a famous painting in 1301 of the Nativity scene with Halley’s Comet in the sky over Europe.

But Mr Lunn says this is impossible: “Halley’s Comet is bright and it moves across the sky, but it only appeared in 12BC, so the time doesn’t fit.”

Another theory is a conjunction, or gathering, of planets moving across the sky. Computer programmes show conjunctions of Jupiter and Venus occurring in 7BC and 3BC: “The timing isn’t right and conjunctions are quite a regular occurrence,” says Lunn. “They would not be unique or special enough.”

Meteors and shooting stars are another possibility, but, argues Mr Lunn, although these are bright, they burn too briefly. He also rules out a super nova star, which destroys itself in a massive explosion lasting for months or years: “It is very, very bright and leaves so much evidence we can identify where and when it happened. But the closest one occurred in 185AD, which is too far off,” he says.

A nova, or an exploding star, says Mr Lunn, is all we are left with. It occurs when one star pulls gas from the other until it erupts. While the effect is usually quite faint, a very bright nova is rare enough to be significant.

And, just like the star described in the Bible, it can appear in the sky suddenly and disappear just as quickly, as if by magic.

Previously, the nova theory had been ruled out as it was thought a planet could only explode like this once. Since a particularly bright nova had gone off in just the right area in 1925, it was assumed it couldn’t have occurred before that.

“But in recent years, science has moved on,”

says Mr Lunn. About 20 years ago, astronomers discovered a Nova can occur in the same star more than once. And a trawl through Chinese astronomy records revealed a nova occurring in this area for 70 days from March to April in 5BC.

“That’s what we were looking for,” says Lunn. “With no CCTV cameras around at the time, we can’t be 100 per cent accurate about what happened, but Chinese astronomers saw a bright star in the sky in the same area as the one that burned in 1925 at the time of year, which fits in with the newly-calculated date for the birth of Christ being in 5BC.

“My conclusion is that the Star of Bethlehem was a nova.”

But he does not rule out the possibility of a miracle: “I am looking at the cold, hard facts and scientific research indicates something actually happened. What was reported was a real, astronomical event. People saw it.

“But anything is possible and how you define it is up to the individual. We can still be open to the mystery of the miracle.”