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| Spacewatch Friday - Star of Bethlehem: Going Back in Time to Examine Its Origins
By Joe Rao
Special to SPACE.composted: 07:00 am ET
20 December 2002 |
It seems almost traditional at this time of year for stargazers to ponder the age-old question of the possible origin of the Star of Bethlehem. Was the so-called Christmas Star an unusual, eye-catching gathering of naked-eye planets, or was that fabled "sign in the sky" a meteor, comet, nova, or indeed something supernatural?
New knowledge of the old astrological beliefs and modern computer-based planetary tables may yet shed new light on this age-old question. But before going back in time to explore the possible answers, one needs to understand the many problems behind the questions.
There are many factors that contribute to the puzzle, including the uncertainty in the actual date of Christs birth and the terminology used to describe celestial events during the Stars appearance some 20 centuries ago. For instance, any heavenly object bright enough to attract attention was apt to be called a "star." Meteors, for instance, were "shooting" or "falling " stars; comets were "hairy" stars; novae were "new" stars and planets were "wandering" stars.
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Fixing an elusive date
The Bible says nothing about the calendar date of the Nativity, but does refer to historical personages and events, such as the reign of King Herod. Modern historical research suggests that Herod may have died sometime between 4 BC and 1 BC by our present calendar. The Magi are said to have visited Herod just before he died, and presumably the birth of Christ and appearance of the Star came sometime before that.
And it is very doubtful that Jesus was born in late December. For one thing, the Biblical passage in St. Luke, "And there were in the same country shepherds abiding in the field, keeping watch over their flock by night," indicates that spring is the likely season; that was when the shepherds in Judea were tending the newborn lambs.
In ancient times, Dec. 25 was the date of the lavish Roman festival of Saturnalia. It was a time when gifts were exchanged; homes, streets and buildings were decorated; people came home for the holidays and everybody was in a happy, party mood. It has been said that early Christians chose the date of the Saturnalia in order to avoid attention and thus escape persecution.
When the Roman emperor Constantine officially adopted Christianity in the 4th century, the date of Christmas remained Dec. 25.
Christs birth almost certainly did not occur 2,002 years ago. Our present chronology by which the years are numbered as AD or BC was conceived by the Roman abbot Dionysius Exiguus around 523 AD.
Unfortunately, Dionysius made two significant errors in his calculations. The first was his placement of 1 AD immediately following 1 BC, completely disregarding the mathematically required 0 in between. Back then in Europe, zero was not considered a number. So, for instance, the year we now call 3 BC, is actually 2 numerically speaking.
Second, Dionysius accepted the statement of Clement of Alexandria that Jesus was born in the 28th year of the reign of the Roman emperor Caesar Augustus. But Dionysius failed to realize that during the first four years of his reign this Roman ruler was known by his original name Octavianus, until the Roman senate proclaimed him "Augustus." So here alone we have an error of four years, but by the time it was realized our chronology was too well entrenched to be changed.
As for the time for the appearance of the Star, most astronomers and Biblical scholars believe that it most likely occurred sometime between the years 7 and 2 BC. So this is the time frame that we need to explore to determine if there was anything unusual in the sky that might have caught the attention of the Magi.
What was it?
At least four theories have been advanced to explain the Star from a purely astronomical viewpoint.
Possibly the first idea put forward was that it was an unusually bright fireball meteor seen streaking toward the horizon. But as most skywatchers know, such an object can be seen to flash across the sky in a mere matter of seconds hardly long enough to lead the Magi halfway across the Orient to the little town of Bethlehem. So we can confidently lay this concept to rest.
Not so easily dismissed, however, is the possibility that the Star was a bright comet.
Comets can remain visible to the unaided eye for weeks either in the predawn sky or at dusk. It is not impossible to conceive that a comet with a bright star-like head and long gossamer tail pointing like some cosmic finger toward the horizon could have drawn the Magi to Bethlehem.
The famous Halleys Comet, last seen in early 1986, also flared in the sky during August and September in the year 11 BC. However, most authorities dismiss it due to the poor time fit. Although it seems unlikely that another great comet could have appeared nearer to the accepted time frame of the Stars appearance and went unrecorded, we can never really be sure.
Besides, comets were viewed as omens of evil, such as floods and famine as well as the death not the birth of kings and monarchs. The Romans, in marking the death of the Roman General Agrippa, for example, used the 11 BC apparition of Halleys Comet as a benchmark. With this in mind, comets would seem to be wrong as the heavenly sign that would signal the coming of a newborn king.
Exploding star
Perhaps the simplest answer is a nova or supernova outburst: a new star blazes forth where none had ever been seen and leaves no trace for us to find in the future.
Although their names imply a new creation, these spectacular objects are in reality dying stars, although they are new (albeit temporary) additions to the nighttime sky. The appearance of a nova is unpredictable a really bright one becomes visible perhaps once every 25 or 30 years.
Going on this assumption, we actually should be due for a bright naked-eye nova at almost anytime now, since the most recent one appeared back in 1975 (not far from the bright star Deneb in the constellation Cygnus).
Most bright novae suddenly and unexpectedly flare into prominence literally overnight, attracting the instant attention of sky-conscious people. But after several days or weeks of such prominence, it gradually fades back to obscurity.
Even more spectacular but much rarer are supernovae; stars that suddenly blow themselves completely apart, briefly producing an incredible energy output equivalent to the combined light of an entire galaxy of stars.
At the height of its outburst, a supernova can shine with a brilliance capable of casting shadows and can even be seen in broad daylight truly a celestial announcement worthy of the birth of a king.
In our Milky Way galaxy, over the past thousand years, there have been four brilliant supernovae, in 1006, 1054, 1572 and 1604. Clearly, we are long overdue for another, though the stars don't necessarily play by any odds we might calculate.
Although a nova or supernova is the most satisfying explanation for the Star, there is a serious problem with it, in that there doesnt seem to be any definitive record of a bright nova appearing in the sky during the time that biblical historians believe the Magi made their journey.
One nova apparently did appear, bordering the constellations Capricornus and Aquarius during the spring of 5 BC. But the Chinese records, which describe this object, imply that it was apparently not very conspicuous at all.
Perhaps a planet
The final possibility is one or more of the bright naked eye planets.
The likelihood that the Magi could have confused one or more of the familiar planets with a star seems remote. However, sometimes two or more of these restless wanderers come together in a striking conjunction. Perhaps a planetary grouping of particular beauty; an exceptionally close conjunction of two planets or groupings of three or more creating an eye-catching geometric figure in the sky may have taken place between the years 7 and 2 BC.
A gathering like that would be quite unusual to the unexpecting eye.
One such event that is often cited occurred on the evening of Feb. 25, 6 BC involving Mars, Jupiter and Saturn, and happened in the constellation of Pisces, the Fishes. If you have ever visited a planetarium for the traditional Christmas show, you probably already know the thrill of watching as the planetarium projector races back through time to recreate this unusual event.
Another possible explanation for the Star of Bethlehem is the three-times passing of Jupiter and Saturn between May and December in 7 BC; a rare triple or "great conjunction."
Jupiter appeared to pass one degree north of Saturn on May 29; practically the same on Sept. 30; then finally a third time on Dec. 5.
There is no doubt about the visibility of these events, mostly opposite to the Sun in nighttime skies. As for their astrological impact, the Magi would have certainly noticed that both planets did not appear to separate widely between their conjunctions. In fact, for eight consecutive months the time it might have taken to travel the 500 miles or more from Babylonia to Judea Jupiter and Saturn remained within three degrees of each other, from late April of 7 BC until early January of 6 BC.
A fist held on an outstretched arm covers about 10 degrees of sky.
But perhaps no other planetary grouping can equal that of the two brightest planets Venus and Jupiter for the explanation that we seek. And if we take the only known account of the Star literally, as given in St. Matthew, then what we really need is the appearance of not just one, but two "stars." The first appearance would have been seen well in advance of the Magis arrival in Bethlehem, and the other at the end of their long journey.
Perhaps the signal for their star was to be a sign in the constellation of Leo, the Lion.
To the early Israelites, Leo was a constellation of great astrological significance and considered a sacred part of the sky. A very close conjunction of Venus and Jupiter would have been visible in the eastern dawn sky of the Middle East from about 3:45 to 5:20 a.m. on Aug. 12, 3 BC.
When they first emerged above the eastern horizon, the two planets were separated by only about two-fifths of the Moons apparent diameter or 12 minutes of arc. As a comparison, the separation of the stars Mizar and Alcor in the handle of the Big Dipper is also 12 minutes. Planets this close are very striking, if they don't differ too much in brightness.
Incidentally, St. Matthew wrote that the Magi stated in their meeting with King Herod: "We have seen his Star in the East and have come to worship him." It has never been clear if they saw the star in the eastern sky, or if they saw it from the East. The fact that the Aug. 12, 3 BC conjunction of Venus and Jupiter occurred in the eastern sky and may have also started the Magi on the journey (from the East) to Bethlehem means that both bases are covered with their statement -- reported by St. Matthew -- to King Herod.
Venus ultimately vanished into the glare of the Sun, but Jupiter and Leo remained in the night sky during the next ten months. During this time a number of additional planetary conjunctions took place, all of which would have been of great importance to the priest-astrologers of the time.
Encore
Then, during June of 2 BC, as Jupiter and the stars of Leo began to sink into the western evening twilight, Venus again returned to this same region of the sky for an even more spectacular encore.
The Magi certainly would have especially taken note that on the evening of June 17, when Jupiter and Venus appeared even closer together than they did in the dawn skies of the previous August. As the planets slowly descended toward the horizon they got closer and closer together.
Finally, at 8:30 p.m. local time they drew to within a mere 0.6 of an arc minute of each other while appearing to hover some 15 above the western horizon. To the Magi the two brightest planets must have appeared to coalesce into one and glowed before them like a dazzling beacon over Judea. Eyeglasses were many centuries in the future, so only people with perfect eyes would have seen the planets separated.
See for yourself
Astronomy can tell us that all these planetary conjunctions indeed occurred. In fact, users of the software package Starry Night Pro can go back in time and view all these planet configurations for themselves on their home computers and try to judge which of these might have appeared the most impressive to the Magi.
But whether anyone actually observed them, and if any of these sent the Magi on their historic journey, are all matters for conjecture.
And finally, was the Star of Bethlehem truly a miracle star? Indeed, a star of stars appearing just once in the history of man? Reaching a conclusion on this subject is not easy, for any natural theory for the Star of Bethlehem can only be at best, just an educated guess.
Perhaps this is a mystery that modern science can never truly unravel. Astronomy has taken us as far as it can go.
The final decision is yours, alone.
