by The Great Christ Comet- Revealing the True Star of Bethlehem (retail) (epub)
28.00
25.71
87.76
211.42
-14.80
1.163
0.334
0.713
16.8
50.5
234.5
126.2
1.26
27.00
24.62
88.12
211.78
-14.87
1.128
0.351
0.689
15.9
50.5
235.3
125.4
1.20
26.00
23.51
88.53
212.20
-14.94
1.099
0.370
0.664
14.9
50.4
236.2
124.6
1.16
25.00
22.40
89.00
212.68
-15.02
1.075
0.390
0.638
14.0
50.4
237.2
123.7
1.12
24.00
21.28
89.53
213.22
-15.11
1.056
0.412
0.610
13.2
50.3
238.3
122.6
1.09
23.00
20.15
90.15
213.85
-15.21
1.040
0.436
0.581
12.3
50.3
239.6
121.4
1.06
22.00
19.00
90.87
214.59
-15.33
1.029
0.462
0.551
11.5
50.2
241.1
119.9
1.04
21.00
17.83
91.73
215.47
-15.46
1.021
0.491
0.519
10.6
50.1
243.0
118.2
1.03
20.00
16.64
92.75
216.51
-15.62
1.017
0.523
0.486
9.8
50.0
245.2
116.1
1.03
TABLE 14.1 The orbital possibilities for the meteoroid stream that caused the Hydrid meteor storm if it was observed from Babylon to radiate from γ (Gamma) Hydrae 1 hour 6 minutes before sunrise* on October 19, 6 BC (as calculated by Dr. David Asher of the Armagh Observatory). “Vinf” is the pre-atmospheric velocity (km/sec); “Vg” the geocentric velocity (km/sec); “Z_t” the distance of the radiant from the zenith (taking into account the analysis of P. S. Gural, “Fully Correcting for the Spread in Meteor Radiant Positions Due to Gravitational Attraction,” WGN, Journal of the International Meteor Organization 29.4 [2000]: 134–138); “lambda” and “beta” the radiant as it would have been observed (before correction for zenith attraction); “a” the semi-major axis of the meteoroid stream (in AU); “q” the perihelion distance (in AU); “e” the eccentricity of the orbit; “i” the inclination of the orbital plane; “Node” the ascending node; “ω” the argument of perihelion; “f” the true anomaly; and “P” the orbital period (in years).
NOTE: *Absolute precision regarding the moment when the meteor storm occurred is not required for our purpose, that is, getting a sense of the orbital characteristics of the meteoroid stream responsible.
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.
Vinf
Vg
Z_t
lambda
beta
a
q
e
i
Node
ω
f
P
Halley-type
51.00
49.78
75.33
195.10
-25.33
15.376
0.259
0.983
80.0
51.2
241.0
119.3
59.47
Jupiter-type
50.00
48.75
75.38
195.15
-25.34
7.228
0.254
0.965
78.3
51.2
239.3
120.9
19.55
49.00
47.73
75.42
195.20
-25.35
4.777
0.249
0.948
76.5
51.2
237.7
122.5
10.48
48.00
46.70
75.47
195.25
-25.37
3.597
0.245
0.932
74.7
51.2
236.2
124.0
6.84
47.00
45.67
75.52
195.31
-25.38
2.905
0.241
0.917
72.8
51.1
234.7
125.5
4.95
46.00
44.64
75.58
195.37
-25.40
2.450
0.237
0.903
70.9
51.1
233.3
126.9
3.82
45.00
43.61
75.64
195.43
-25.42
2.129
0.234
0.890
68.9
51.1
231.9
128.3
3.1
Other
44.00
42.58
75.71
195.50
-25.44
1.891
0.232
0.877
66.9
51.1
230.6
129.6
2.59
43.00
41.54
75.77
195.57
-25.46
1.707
0.230
0.866
64.8
51.1
229.4
130.9
2.25
42.00
40.51
75.85
195.65
-25.48
1.562
0.228
0.854
62.7
51.1
228.2
132.0
1.95
41.00
39.47
75.93
195.74
-25.51
1.445
0.227
0.843
60.6
51.1
227.1
133.1
1.74
40.00
38.43
76.02
195.83
-25.53
1.348
0.227
0.832
58.5
51.1
2
26.1
134.1
1.57
39.00
37.39
76.11
195.93
-25.56
1.267
0.228
0.820
56.3
51.1
225.2
135.0
1.43
38.00
36.34
76.21
196.03
-25.59
1.199
0.229
0.809
54.1
51.1
224.4
135.9
1.31
37.00
35.30
76.32
196.15
-25.63
1.141
0.231
0.798
51.9
51.0
223.6
136.6
1.22
36.00
34.25
76.44
196.28
-25.66
1.092
0.233
0.786
49.7
51.0
222.9
137.3
1.14
35.00
33.20
76.58
196.42
-25.70
1.049
0.237
0.774
47.6
51.0
222.4
137.9
1.07
34.00
32.14
76.72
196.57
-25.74
1.012
0.241
0.762
45.4
51.0
221.8
138.4
1.02
33.00
31.08
76.88
196.74
-25.79
0.980
0.246
0.749
43.2
51.0
221.4
138.9
0.97
32.00
30.02
77.06
196.93
-25.84
0.952
0.252
0.735
41.1
51.0
221.1
139.2
0.93
31.00
28.95
77.25
197.14
-25.90
0.928
0.260
0.720
39.0
51.0
220.8
139.5
0.89
30.00
27.87
77.47
197.37
-25.96
0.908
0.268
0.705
36.9
50.9
220.7
139.7
0.87
29.00
26.79
77.71
197.62
-26.03
0.890
0.277
0.688
34.9
50.9
220.6
139.8
0.84
28.00
25.71
77.98
197.91
-26.11
0.875
0.288
0.671
32.9
50.9
220.6
139.8
0.82
27.00
24.62
78.29
198.24
-26.20
0.863
0.301
0.652
30.9
50.9
220.7
139.7
0.80
26.00
23.51
78.64
198.61
-26.29
0.853
0.314
0.631
29.0
50.8
220.9
139.5
0.78
25.00
22.40
79.03
199.04
-26.40
0.846
0.330
0.610
27.1
50.8
221.2
139.3
0.78
24.00
21.28
79.49
199.53
-26.53
0.841
0.348
0.586
25.3
50.8
221.6
138.9
0.77
23.00
20.15
80.01
200.09
-26.67
0.838
0.367
0.561
23.5
50.7
222.2
138.3
0.76
22.00
19.00
80.63
200.76
-26.84
0.837
0.390
0.534
21.7
50.7
223.0
137.6
0.77
21.00
17.83
81.36
201.54
-27.03
0.839
0.415
0.505
20.0
50.6
223.9
136.7
0.77
20.00
16.64
82.22
202.49
-27.25
0.843
0.444
0.474
18.4
50.6
225.2
135.5
0.78
19.00
15.43
83.27
203.63
-27.51
0.851
0.476
0.440
16.7
50.5
226.8
133.9
0.78
TABLE 14.2 The orbital possibilities for the meteoroid stream that caused the Hydrid meteor storm if it was observed from Babylon to radiate from HIP59373 1 hour 6 minutes before sunrise on October 19, 6 BC (as calculated by Dr. David Asher of the Armagh Observatory). For abbreviations, see Table 14.1.
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.25
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).26 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).27
In addition, it should be noted that within the large population of near-Earth asteroids are an unknown number that are cometary in nature (like Apollo asteroid 4015 Wilson-Harrington = Comet 107P/Wilson-Harrington) or are remnants of comets. It is therefore perhaps worth pointing out that some objects classified as Apollo asteroids have orbits that are similar to possible orbits of the meteoroid stream that caused the Hydrid meteor storm of 6 BC. Of course, we must remember that 2,000 years of orbital evolution may mean that the orbit of the Hydrid meteoroid stream is no longer recognizably similar to the orbits of these asteroids.
The orbit of Apollo asteroid 2009 HU58 (magnitude 19) is reminiscent of the orbit of the meteoroid stream responsible for the 6 BC meteor storm if the latter’s meteors radiated from one-third of the way from γ Hydrae to HIP59373 (table 14.3).
Name
q
e
i
ω
Node
Period
2009 HU58
0.187
0.91
35.77
285.35
62.90
2.97 years
Hydrids (Vinf=40)
0.19
0.908
39.3
226.1
51.0
2.97 years
TABLE 14.3 A comparison of the orbit of asteroid 2009 HU58 to the orbit of the meteoroid stream responsible for the 6 BC Hydrids, assuming that the meteors radiated from one-third of the way from γ Hydrae to HIP59373 and that Vinf=40.
The orbit of the Apollo asteroid 2000 UR16 (magnitude 23) is reminiscent of the orbit of the meteoroid stream responsible for the 6 BC meteor storm if the latter’s meteors radiated from two-thirds of the way from γ Hydrae to HIP59373 (table 14.4).
Name
q
e
i
ω
Node
Period
2000 UR16
0.507
0.4388
11.74
228.78
33.85
313.64 days
Hydrids (Vinf=19)
0.501
0.444
13.8
233.7
50.4
312.42 days
TABLE 14.4 A comparison of the orbit of asteroid 2000 UR16 to the orbit of the meteoroid stream responsible for the 6 BC Hydrids, assuming that the meteors radiated from two-thirds of the way from γ Hydrae to HIP59373 and that Vinf=19.
The orbit of Apollo asteroid 2004 WK1 (magnitude 21) is reminiscent of the orbit of the meteoroid stream responsible for the 6 BC meteor storm if the latter’s meteors radiated from HIP59373 (table 14.5).