by The Great Christ Comet- Revealing the True Star of Bethlehem (retail) (epub)
What did the comet look like when it set from October 24 to November 30/December 1? During that period the comet was shrinking. Indeed, if the Magi had drawn images of the comet just before it set every night and flicked through an ordered collection of them quickly, they would have got a very clear vision of what was happening in outer space (fig. 10.32)—the comet was passing Earth and moving away into the distance. After all, the comet was passing by Earth (its closest approach to Earth [perigee] was October 24/25) and then getting farther and farther away from it (fig. 10.33).
FIG. 10.32 The orientation and location of the Christ Comet as it set from October 31 to November 30/December 1, 6 BC. Image credit: Sirscha Nicholl.
FIG. 10.33 Perigee: when the Christ Comet was closest to Earth (October 24/25, 6 BC). Image credit: Sirscha Nicholl.
From October 24 onward the comet’s apparent magnitude also weakened. On October 24 the comet’s apparent magnitude was at least -12.1,86 the condensed part of its coma visible in the daytime. By November 23 the magnitude was down to (at least) -4.8; by November 30 it was down to (at least) -4.0.87 Moreover, the brightness boost due to the phenomenon of “forward-scattering” quickly subsided as the comet’s position relative to Earth changed radically on October 24–28. However, the effect of the weakening magnitude was counterbalanced by the comet’s shrinkage, because the brightness that the comet did have was being distributed over a smaller surface area, concentrating it. In the early days of the Magi’s journey the coma would have been massive, but from October 24/25 it steadily decreased in size. By November 23 and 30 it may have been about 1.75 to 2 degrees long and 0.7 to 0.8 degrees wide.
Throughout this period the comet functioned as a giant celestial guide, urging the Magi to journey westward on their way to Judea. At each nightly setting the Star moved over the horizon as though it were traveling in that direction. The advance of the long-tailed comet over the horizon must have given the Magi the distinct impression that it was moving on ahead of them. Just as, when you watch someone walking over a hill, the person’s body gradually disappears, first the feet and then upwards from there, so the comet disappeared slowly but surely from the coma upwards. From very shortly after they set out on their journey, right through until their arrival in Jerusalem, the ever-shortening comet would have been last seen in the west, in front of them.88
One can well imagine that, as the Magi approached Jerusalem, the Star seemed to set right over the city, appearing to signal that this was their final destination.
The Star at the Climax of the Magi’s Journey
The big question, of course, is: What did the comet do on the day when the Magi traveled from Herod’s palace in Jerusalem to Bethlehem, and as they looked for the house where the baby Messiah was—between November 23/24 and November 30/December 1, 6 BC? The analogies used above are helpful for grasping what the comet did on each of those nights. As the Magi set out on their way, around sunset, the cometary coma appeared just under the ribbon connected to the tail of the western fish of Pisces89 in the south-southeast, the comet stretching back approximately 33–38 degrees into Aries in the east. Over the couple of hours from the time when the comet did appear, as the Magi walked from Jerusalem to Bethlehem, it advanced, along with the fixed stars and constellations, to the south-southwest, precisely the direction of Bethlehem from Jerusalem.
We shall consider November 23 and 30 in turn.
With respect to the 23rd, when the approximately 38-degree-long comet became visible around sunset, it would have been seen at an altitude of 44 degrees in the south-southeast, with its tail sweeping back toward the east. As it progressed on its nightly course through the sky it would have increasingly moved toward the Magi as they traveled to Bethlehem. 1½ hours after sunset, the nucleus was at an altitude of 49 degrees in the south (the comet’s highest point, or culmination). Thereafter, over the next 30 minutes it dropped in altitude very slowly and imperceptibly, down a fraction of a degree (to 48½ degrees). At this point it was in the south to south-southwest. If the 23rd was the night on which the Magi traveled from Jerusalem to Bethlehem, the Magi probably arrived at the town of their destination around this time, for the coma was then high in the sky in the direction of Bethlehem, and hence would have been directly in front of the Magi, with its long tail streaking back to their left. Accordingly, the Sun must have set and the Star appeared toward the beginning of their evening journey from Jerusalem to Bethlehem.
As for the 30th, the situation was very similar: the now 33-degree-long comet appeared at sunset in the south-southeast, with the tail sweeping toward the east. Its altitude at that time was about 46½ degrees. Over the next 70 minutes or so it ascended to about 50 degrees, at which point it was at its culmination in the south. After that it began to descend; over the next 50 minutes it dropped almost 2 degrees. At the end of that time it was in the south-southwest, the tail sweeping high into the southeast. Again, in this scenario the Magi would have arrived in Bethlehem around that time. Accordingly, the Sun must have set and the Star appeared toward the start of their short journey.
Either way, as Matthew reports, it really would have seemed that the Star was going ahead of them to Bethlehem (Matt. 2:9b). See fig. 10.34.
FIG. 10.34 The Christ Comet over the two hours starting at sunset on the evening when the Magi made their way from Jerusalem to Bethlehem. Image credit: Sirscha Nicholl.
In both scenarios, assuming that the Magi arrived in Bethlehem 2 hours after sunset, it would have been something like 5 hours later that night that the comet set in the west. As the comet advanced westward with the rotating sky, it was descending in altitude, moving toward the Magi, and adjusting its apparent angle (along with the ecliptic) until it set at a slight tilt—leaning about 10 degrees off vertical. This behavior is what Matthew had in mind when he stated that it “came” and then “stood” over the house (v. 9b).90 From the vantage point of the Magi, the comet as it set seemed to be pinpointing one particular house on the west-southwestern horizon of Bethlehem. It seems that the Magi were located to the east-northeast of the house, directly opposite the comet. The sunward side of the coma appeared to be located just above the house, from their perspective, and the tail was streaking up alongside the ecliptic toward the roof of the sky (fig. 10.35).91
FIG. 10.35 The Christ Comet as it set on the night the Magi arrived in Bethlehem. Image credit: Sirscha Nicholl.
By November 23/24–November 30/December 1 the comet would have decreased considerably in apparent magnitude from what it had been at the start of their journey. At the same time, however, the comet was shrinking in size, intensifying the brightness that it did have. The comet’s brightness was evidently sufficient for the Magi to see it shortly after sunset as they walked from Jerusalem to Bethlehem. Gary W. Kronk comments, “The comet would have been located far from twilight and certainly would have been a striking object in the evening sky, being visible from about 6 p.m.”92 Indeed the comet would have been a stunning sight. Its magnitude was at least -4.8 as it set on November 23/24, 6 BC.93 On the night of November 30/December 1 it was at least -4.0, comparable to the magnitude of Venus.94 (See tables 10.8–9.)
Magnitude Slope
(value of n)
Apparent Magnitude on the evening of November 23, 6 BC, if first observed on November 21–28, 8 BC
Apparent Magnitude on the evening of November 23, 6 BC, if first observed on February 5, 7 BC
Apparent Magnitude on the evening of November 23, 6 BC, if first observed on May 29, 7 BC
Apparent Magnitude on the evening of November 23, 6 BC, if first observed on August 17, 7 BC
Apparent Magnitude on the evening of November 23, 6 BC, if first observed on September 30, 7 BC
Apparent Magnitude on the evening of November 23, 6 BC, if first observed on December 10–17, 7 BC
3
-6.6
-6.4
-5.4
-4.3
-4.0
-3.7
4
/>
-8.4
-8.2
-7.0
-5.8
-5.4
-4.8
5
-10.2
-9.9
-8.5
-7.2
-6.7
-6.0
TABLE 10.8 The Christ Comet’s apparent magnitude on the evening of November 23, 6 BC. The values are essentially the same for the comet’s setting later that night.
Magnitude Slope
(value of n)
Apparent Magnitude on the evening of November 30, 6 BC, if first observed on November 21–28, 8 BC
Apparent Magnitude on the evening of November 30, 6 BC, if first observed on February 5, 7 BC
Apparent Magnitude on the evening of November 30, 6 BC, if first observed on May 29, 7 BC
Apparent Magnitude on the evening of November 30, 6 BC, if first observed on August 17, 7 BC
Apparent Magnitude on the evening of November 30, 6 BC, if first observed on September 30, 7 BC
Apparent Magnitude on the evening of November 30, 6 BC, if first observed on December 10–17, 7 BC
3
-5.8
-5.6
-4.6
-3.5
-3.2
-2.9
4
-7.6
-7.4
-6.2
-5.0
-4.6
-4.0
5
-9.3
-9.0
-7.6
-6.3
-5.8
-5.1
TABLE 10.9 The Christ Comet’s apparent magnitude on the evening of November 30, 6 BC. The values are essentially the same for the comet’s setting later that night.
The 13-day waxing gibbous and 19-day waning gibbous Moon were in the sky for the comet’s setting on the 23rd/24th and the 30th/1st, respectively.95 On the 23rd/24th the comet in outer space was 1.09 AU from Earth and 1.54 AU from the Sun. On November 30/December 1 it was 1.33 AU from Earth and 1.66 AU from the Sun. The comet was just beyond the orbit of Mars.96 See figs. 10.36–37.
FIG. 10.36 The Christ Comet in outer space on November 23, 6 BC. It is just beyond the orbit of Mars. Image credit: Sirscha Nicholl.
FIG. 10.37 The Christ Comet in outer space on November 30, 6 BC. It is beyond the orbit of Mars. Image credit: Sirscha Nicholl.
As the comet set between November 23/24 and November 30/December 1, Jupiter was above the coma in the constellation Aries, 42½–45 degrees off the horizon, while Saturn, in the constellation Pisces, was even closer to the coma, hovering just 20½–22½ degrees above the horizon, approximately halfway between the coma and Jupiter. The comet’s impressively long tail would have extended upwards from the horizon right past Saturn toward Jupiter. To someone surveying the scene as a whole from the Magi’s perspective, around the time of the comet’s setting, the tailed comet would have seemed like a massive pointer directed downwards from Jupiter, past Saturn, to the Messiah’s house. It may have looked as if Jupiter was pinpointing the location of the Messiah, the one destined to reign on behalf of Israel, represented by Saturn. This was an awesome climax to the Magi’s journey, and indeed to the entire cometary apparition.
Of course, the comet had first appeared during a year dominated by the three Jupiter-Saturn conjunctions of 7 BC (climaxing on May 27–31, September 26–October 5, and December 1–8). Indeed it is very possible that the Bethlehem Star was first observed in connection with one of those conjunctions. In light of this, the fact that Jupiter and Saturn were present for the climax of the comet’s apparition may well have been deemed especially significant. The Magi may already have come to the settled conviction that Jupiter had played the part of the Most High God, Saturn the role of Israel, and the “star” that of the one destined to exercise sovereignty over the earth on behalf of Israel. Needless to say, if the comet did first appear during the Jupiter-Saturn triple conjunction, this climactic scene in Bethlehem would have meant that a beautiful celestial inclusio bracketed the whole cometary apparition.
The comet, the coma of which had played the role of the messianic baby in Virgo in the great celestial drama in the eastern sky just over a month before, had now led the Magi to the very building on the earth where the baby was.
11
“Brightest and Best of the Sons of the Morning”
The Greatest Comet in History
What the Bethlehem Star comet did in 7–6 BC was astonishing and obviously unique. It was clearly a magnificent comet, but how does it compare with the other great historical comets?
The Marks of Great Comets
In an earlier chapter we set out the marks of great comets. They must have some, if not all, of the following characteristics. They should (1) make a close pass by the Sun, no more than about 1 AU from it; (2) make a close pass by Earth; (3) provide good viewing opportunities for human observers; (4) be very productive; (5) have a clearly visible tail, at least 10 degrees in length; (6) have a large nucleus and notable coma; and (7) be at least as bright as the sky’s more distinguished stars. Some great comets may have deficiencies (e.g., they may be farther from the Sun and/or Earth), but their other traits will make up for these.
The Christ Comet has all the marks of a truly great comet. Indeed its qualifications for greatness supersede those of any other comet in recorded history. It is quite simply the greatest of the great historical comets.
A Close Pass by the Sun
The Bethlehem Star Comet came as close as 0.119 AU, or 17.8 million km, from the Sun. In the league of the Great Comets, as established by Don Yeomans in April 2007,1 it would be 8th out of the 66 in this regard.2 It is superseded only by sungrazers—the Great Comet of 1680 (0.006 AU)3 and established members of the Kreutz sungrazing family, specifically the Great March Comet of 1843 (0.0055 AU), the Great September Comet of 1882 (0.00775 AU), and Ikeya-Seki in 1965 (0.0078 AU)—and two sunskirters, the Great Southern Comet of 1865 (0.026 AU) and the Great Comet of 1668 (0.07 AU), and by one NI comet, the Great Comet of 1665 (0.106 AU). The 6 BC Comet’s perihelion distance is slightly closer to the Sun than Messier’s Comet of 1769 (0.123 AU), which had a tail of over 90 degrees,4 and the Great January Comet of 1910 (0.13 AU), which sported a 50-degree tail. It is worth remembering that the Great Comet of 1811 achieved greatness even though it was 1.04 AU from the Sun at perihelion, and the magnificent Hale-Bopp made it only to 0.91 AU from the Sun.
A Close Pass by Earth
As regards making a close pass by Earth (perigee distance), the Christ Comet came as close as 0.1045 AU, or 15.63 million km, on October 24/25, 6 BC. In that regard it would rank 12th in Yeomans’s list of great comets. The great comets ahead of it in perigee distance are Halley’s Comet in 837 (0.03 AU), followed by the Great Comet of 1132 (0.04 AU), the Great Comet of 1472 (0.07 AU), the Great Comet of 1556 (0.08 AU), the Great Comet of AD 400 (0.08 AU), Halley’s Comet in AD 374 and 607 (0.09 AU), the Comet of AD 568 (0.09 AU), Hyakutake in 1996 (0.1018 AU), the Comet of AD 390 (0.1037 AU), and Halley’s Comet in 1066 (0.104 AU).5 It should be noted that 4 of these 11 are different apparitions of the same comet, 1P/Halley. When one considers how magnificent the great comets of 1807 and 1811 were, when they came no closer than 1.15 AU and 1.22 AU respectively from Earth, and how stunning Hale-Bopp was, even though it never came closer to Earth than 1.32 AU, one begins to appreciate the significance of the Christ Comet’s high perigee ranking. Moreover, it should be remembered that the Christ Comet actually made two close passes by Earth—on August 14, 6 BC, on its way toward perihelion, it came as close as 0.334 AU to Earth.
A Combination of Close Passes by the Sun and by Earth
When one considers the perihelion and perigee distances together, the Christ Comet emerges at the top of the list.
Of the 7 great comets with perihelion distances closer than that of the Christ Comet, the one that came nearest to Earth was the Great Comet of 1680 (Kirch’s Comet)—it was 0.42 AU away. The next closest was the Great Comet
of 1665, which came to about 0.57 AU from Earth.
Of those great comets that came as close to Earth as the Christ Comet, or closer, the ones that came nearest the Sun were the Great Comet of AD 400, which was only 0.21 AU from the Sun, Hyakutake (fig. 11.1), whose perihelion distance was 0.23 AU, and the comets of 1471 and 1556, both of which came as close as 0.49 AU to the Sun.
FIG. 11.1 Comet Hyakutake on April 17, 1996. Image credit: Bojan Dintinjana and Herman Mikuz, Črni Vrh Observatory, Slovenia, http://www.observatorij.org.
When one considers the perihelion and perigee distances of all of Yeomans’s great comets, it is the AD 400 comet that holds the record—0.21 AU from the Sun and 0.08 AU from Earth. After it comes Hyakutake—0.23 AU from the Sun and 0.1 AU from Earth—and then Great Comet of 905—0.2 AU from the Sun and 0.21 AU from Earth.
In its combination of perihelion and perigee distances—0.119 AU and 0.1045 AU respectively—the Christ Comet surpasses even the Great Comet of AD 400. It is worth discovering a little more about that comet.
Like the Christ Comet, the Comet of AD 400 made its closest approach to Earth after perihelion. Philostorgius6 referred to this comet as a “star which appeared in the form of a sword,” and Socrates Scholasticus7 mentioned that it was a huge comet of extraordinary magnitude that stretched from the sky to the ground, something unprecedented for those alive at the time.8 Hermias Sozomen9 described it as having “extraordinary magnitude” and being “larger . . . than any that had previously been seen.”10 David Seargent points out that it “holds the record for a double bill of small perihelion and small perigee.”11 He also suggests that its coma was “several degrees in diameter,” that its tail stretched “like a broadening beam of light across tens of degrees of sky,”12 and that it would have cast such strong shadows that people would have been able to read by its light.13 Gary Kronk estimates that this comet had an absolute magnitude of only +6,14 with a maximum apparent magnitude of around 0. However, the fact that this comet was described as simultaneously massive and of extraordinary brightness suggests that its apparent magnitude peak must have been much greater than this. It is possible that the comet had a temporary but dramatic flare-up in the aftermath of its closest approach to the Sun, and that this fizzled out within a couple of weeks of the comet passing Earth. At the same time, Seargent points out that an unimpressive absolute magnitude might have been partly compensated for by the fact that the comet’s angle with respect to the ecliptic was becoming ever narrower throughout the apparition.15
