What’s that bright star?

Seen a very bright star low down in the south-west just after sunset recently? A bright star at Christmastime! What could it be? It’s Venus, but at this time of year it makes us think of the stories of the Star of Bethlehem. So could the appearance of such a star have once persuaded three wise men to trek across the desert…?

If those men were at all wise, they would have been familiar with the appearance of Venus and would just have stayed at home. In those days, learned people were familiar with the movements of the stars and planets, and indeed what we now call astrology was more or less the same thing as astronomy. Today, astrology is rightly regarded as bunkum.

But hold on a moment: we are still strongly affected by movements in the Solar System. We’ve just had the solstice, and every one of us is only too aware of what it means – cold dark mornings, early sunsets, nothing growing in the garden. In earlier times, this was more than an inconvenience. Wise men did indeed study the movements of the stars and planets, to try and work out whether they had any effects on our lives. So they would have been expecting Venus to be there, along with the other planets currently in the evening sky of December 2021 – Jupiter and Saturn and, for a few days around the New Year, Mercury.

Jupiter (top left), Saturn (centre) and Venus (lower right) as seen in December 2021. Photo: Robin Scagell

What would really have got them excited would have been any unusual occurrences, such as the close alignment of two or more planets. Although they would have known perfectly well what planets were involved, it could have been seen as a portent. Such an event occurred this time in 2020, when Jupiter and Saturn were closer together than had been seen for 400 years. Even so, they were clearly visible as two separate objects.

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Jupiter and Saturn close together in December 2020 as seen through a telescope. The inset shows the naked-eye appearance. Photo: Robin Scagell

One candidate for the Star of Bethlehem is a series of close alignments of Jupiter, Venus and the star Regulus, occurring in 3BC and 2BC. But all such planetary candidates run into problems of timing and direction, if you take the story literally. Our notion of the star appearing in the east and guiding the wise men to Bethlehem doesn’t square with the fact that they would have come from the east, and the other details of the story (such as the date of the death of Herod, who is mentioned in the story in the Gospel of Matthew, the only place in the Bible where it occurs).

Other astronomical possibilities include fireballs (which can happen at any time), comets, novae and supernovae, which are the sudden flaring-up of previously invisible stars. But none of the known such events tie in very well. Or, of course, if you prefer, it could have been a miracle, for which almost by definition there is no scientific explanation! If you want to know about any of these explanations, we suggest that you look at the comprehensive Wikipedia article on the topic.

But returning to the view at the moment, if you get the chance do look at Venus through a telescope or even binoculars. Right now it is a thin crescent, as it’s close to Earth. It is rapidly getting close to the Sun as seen in the sky, so will be hard to spot by the end of the year. Jupiter and Saturn will be around during the first part of January, but even Jupiter will be lost in the twilight by the end of January 2022.

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The crescent shape of Venus is easily seen through a small telescope or even binoculars. Photo: Robin Scagell