The Great Christ Comet (60 page)

It is also possible that the meteors radiated from higher up on the tail, which extended approximately as far as the star HIP59373. A meteoroid stream with any of the sets of orbital elements shown in
table 14.2
could theoretically have resulted in a meteor storm radiating from the uppermost part of the tail, where the feet of the Bab­ylo­nian Raven (Greek, Corvus the Crow) rested.

We suggest that the meteors probably radiated from somewhere between
γ
(Gamma) Hydrae and HIP59373. Therefore these tables contain the approximate outer limits of the meteoroid stream's actual orbital elements.
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A cometary asteroid, Jupiter-type comet, Halley-type comet, and long-period comet all remain on the table as possible parents of the meteoroid stream that caused the meteor storm of 6 BC (see
fig. 14.9
). If it was a long-period meteoroid stream, the meteoroids would have had a velocity of about 45 km/second. If the meteoroids hailed from a Halley-type or Jupiter-family comet, they would have had a medium-to-fast velocity (for a Halley-type stream, 43–51 km/second; for a Jupiter-family stream, 38–50 km/second).
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If a cometary asteroid gave rise to the meteoroid stream (3200 Phaethon is the parent of the Geminid meteor shower), the meteors would have had a slow or medium velocity.

Could the meteor storm of 6 BC be related to any current meteor shower? That is difficult to answer, since there is at this point no catalog detailing orbital elements of meteoroid streams or radiants of meteor showers that occurred two millennia ago. Gravitational
factors mean that orbits evolve and hence the orbital elements of the meteoroid stream
then
might no longer resemble what they are
now
(particularly in their argument of perihelion [
ω
] and longitude of the ascending node [
Ω
] values). However, it is still interesting to observe that a few meteoroid streams have orbits that are at least superficially similar to that of the meteoroid stream responsible for the meteor storm in 6 BC.

If the meteors radiated from high on the tail and the meteoroid stream orbit had a semi-major axis of 1.04–1.1 AU, it would be reminiscent of the
μ
and
κ
Hydrid meteor showers (and the related January Hydrids and Iota Sculptorids) not only in perihelion distance (0.233–0.237 AU compared with 0.215 AU and 0.249 AU respectively for the
κ
and
μ
Hydrids) but also in eccentricity (0.77–0.79, compared with 0.79 and 0.77), velocity (33–34 km/second compared with 37.6 and 39.1 km/second), and, to some extent, inclination (48–50 degrees compared with 66.5 and 71.8 degrees).
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