The Great Christ Comet (53 page)

From October 24 onward the comet's apparent magnitude also weakened. On October 24 the comet's apparent magnitude was at least -12.1,
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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.
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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.
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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 Pisces
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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 di
rectly 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
.

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).
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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
).
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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.”
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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.
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On the night of November 30/December 1 it was at least -4.0, comparable to the magnitude of Venus.
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(See tables 10.8–9.)

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.
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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.
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See figs. 10.36–37.