by The Great Christ Comet- Revealing the True Star of Bethlehem (retail) (epub)
68 Gary W. Kronk, Comets: A Descriptive Catalog (Hillside, NJ: Enslow, 1984), 69.
69 John E. Bortle, “The Bright-Comet Chronicles,” International Comet Quarterly (1998), http://www.icq.eps.harvard.edu/bortle.html (accessed March 26, 2014).
70 Andreas Kammerer, “Analysis of Past Comet Apparitions: C/1995 O1 (Hale-Bopp),” http://kometen.fg-vds.de/koj_1997/c1995o1/95o1eaus.htm (last modified June 26, 2007).
71 See “Brightest Comets Seen since 1935,” International Comet Quarterly, http://www.icq.eps.harvard.edu/brightest.html (accessed March 26, 2014); Joe Rao, “The Greatest Comets of All Time,” SPACE.com (January 19, 2007), http://www.space.com/3366-greatest-comets-time.html (accessed March 26, 2014); and Seargent, Greatest Comets, 150, 208–224.
72 “Brightest Comets Seen since 1935.”
73 Seargent, Comets: Vagabonds of Space, 34.
74 Karl Battams, “The Great Birthday Comet of 2011,” http://sungrazer.nrl.navy.mil/index.php?p=news/birthday_comet (last modified December 28, 2011).
75 Kronk, Cometography, 2:130–133. Other instances of especially bright comets being spotted relatively close to the Sun can be found in Seargent, Greatest Comets, 113, 144, and 212; and Kronk, Cometography, 2:506–507.
76 Joseph N. Marcus, “Forward-Scattering Enhancement of Comet Brightness. II. The Light Curve of C/2006 P1 (McNaught),” International Comet Quarterly 29 (2007): 119, 128.
77 Gary W. Kronk, “C/1975 V1 (West),” http://cometography.com/lcomets/1975v1.html (last modified October 3, 2006).
78 “Comet Hale-Bopp: The Great Comet of 1997,” an article on NASA’s Stardust website, http://stardust.jpl.nasa.gov/science/hb.html (last modified November 26, 2003).
79 Crovisier and Encrenaz, Comet Science, 31.
80 Cf. Brandt and Chapman, Introduction to Comets, 258; Littmann and Yeomans, Comet Halley, 74.
81 “Comet in Major Outburst Now Visible in Evening Sky,” an article on the Armagh Observatory’s website in 2010, http://star.arm.ac.uk/press/2007/cometholmes (last modified October 10, 2012).
82 We shall consider comet fragmentation events later in this chapter.
83 On these and other possibilities, see Sergei I. Ipatov, “Cavities as a Source of Outbursts from Comets,” in Comets: Characteristics, Composition, and Orbits, ed. Peter G. Melark (Hauppauge, NY: Nova Science, 2011), 101–112.
84 Schaaf, Comet of the Century, 284.
85 Ibid.
86 Joseph N. Marcus, “Forward-Scattering Enhancement of Comet Brightness. I. Background and Model,” International Comet Quarterly 29 (2007): 61.
87 Ibid., 58.
88 Ibid.
89 Ibid., 56.
90 Marcus, “C/2006 P1 (McNaught),” 119.
91 Marcus, “Background and Model,” 40, 62.
92 Ibid., 59.
93 For this reason, astronomers refer to “surface brightness,” the magnitude of 1 square arcsecond (1/3600 degree) of any given astronomical object. The surface brightness of a comet that is 1 square arcminute (an arcminute is 60 arcseconds or 1/60 degree) will be 10,000 times, and hence 10 magnitudes, brighter than if it were 100 square arcminutes. In ideal observing conditions, such as would generally have prevailed in ancient Babylon, the surface brightness of the night sky is +22 magnitudes per square arcsecond and that of the clear daytime sky approximately +4 (an overcast daytime sky’s surface brightness is about +6). To be seen, an object needs to have a surface brightness greater than the background sky. The Milky Way Galaxy, with its surface brightness of +21, can be seen only in very clear night skies. The full Moon has a surface brightness of approximately +3.6 and so is brighter than a clear daytime sky and hence may be clearly visible even when the Sun is present. Venus, with its surface brightness of +1.9, is also detectable during the day in clear skies to those with excellent eyesight who know exactly where to focus their vision. However, due to its small size, it is more difficult to spot than the Moon. The Sun’s surface brightness is -10.7, Jupiter’s +5.7, Saturn’s +5.9, and Mars’s +3.9 (see Roger Nelson Clark, Visual Astronomy of the Deep Sky [Cambridge: Cambridge University Press, 1990], 11 table 2.3; Mike Luciuk, “Astronomical Magnitudes: Why Can We See the Moon and Planets in Daylight?,” 7 [http://www.asterism.org/tutorials/tut35%20Magnitudes.pdf (last modified April 25, 2013)]; Paul Schlyter, “Radio and Photometry in Astronomy,” http://stjarnhimlen.se/comp/radfaq.html [last modified April 13, 2010]; also “Planetary Photo Techniques,” a webpage of Galactic Photography, http://www.galacticphotography.com/astro_Planetary_technique_3.html [last modified September 9, 2012]). Venus, Jupiter, Saturn, and Mars become clearly visible around sunset, when the sky’s surface brightness is dimming. When the Sun is just 5 degrees above the horizon, a clear sky’s brightness at its zenith is +6.5; 15 minutes after sunset it is +13—at this point one can see stars that have an apparent stellar magnitude (note: not “surface brightness”) of +3.5 (Clark, Visual Astronomy of the Deep Sky, 16). In ideal dark conditions at night, when the sky’s surface brightness is +22, naked-eye observers can generally see stars up to +6.5 apparent stellar magnitude (note: not “surface brightness”). The surface brightness of the middle “star” of Orion’s sword, the Orion Nebula, is +17 magnitudes per square arcsecond, and it is visible to the naked eye at night, even in light-polluted skies.
94 Kronk, Cometography, 2:130.
95 See Yeomans, Comets, 11–14.
96 Sagan and Druyan, Comet, 173–187.
97 See Seargent, Greatest Comets, 154.
98 George F. Chambers, The Story of the Comets (London: Clarendon, 1909), 8–9.
99 See Seargent, Greatest Comets, 141; Kronk, Cometography, 2:294, 295–296, 298, 299.
100 Josephus, J.W. 6.5.3 (§289).
101 Seneca, Natural Questions 7.3.2–3.
102 Ibid., 7.17–18. See Mark E. Bailey, Victor M. Clube, and William M. Napier, The Origin of Comets (Oxford: Pergamon, 1990), 10–11; and Yeomans, Comets, 8.
103 Seneca, Natural Questions 7.
104 Brandt and Chapman, Introduction to Comets, 17. If the inclination is less than 90° to the ecliptic, the comet is prograde; if the inclination is more than 90° the comet is retrograde.
105 “Eccentricity” is the degree to which a celestial body’s orbit deviates from perfect circularity—the eccentricity of a circle is 0; the more stretched the oval is, the higher the eccentricity is, up to 1 (elliptical); an eccentricity of 1 (parabolic) or above (hyperbolic) means that the object is incapable of completing an orbital revolution.
106 The eccentricity and perihelion distance also determine the range of a comet’s velocity.
107 Cf. Guy Ottewell as cited by Schaaf, Comet of the Century, 197.
108 Steel, Rogue Asteroids and Doomsday Comets, 36.
109 H. F. Levison, A. Morbidelli, L. Domes, R. Jedicke, P. A. Wiegert, and W. F. Bottke, Jr., “The Mass Disruption of Oort Cloud Comets,” Science 296 (2002): 2212–2215.
110 Jenniskens, Meteor Showers, 72.
111 For an overview of the greatest sungrazers, see Seargent’s Greatest Comets, 191–224, and his Sungrazing Comets: Snowballs in the Furnace (Kindle Digital book, Amazon Media, 2012).
112 Jenniskens, Meteor Showers, 423–427.
113 Schmude, Comets and How to Observe Them, 17.
114 Ibid., 17–18.
115 Schaaf, Comet of the Century, 71.
116 See Sagan and Druyan, Comet, 96.
117 Carolyn Sumners and Carlton Allen, Cosmic Pinball: The Science of Comets, Meteors, and Asteroids (New York: McGraw-Hill, 2000), 3.
118 So Jenniskens, Meteor Showers, 130–132; Victor Clube and Bill Napier, Cosmic Winter (Oxford: Blackwell, 1990), 148.
119 See Jenniskens, Meteor Showers, 133, on 2P/Encke.
120 David Levy, Comets: Creators and Destroyers (New York: Simon & Schuster, 1998), 29; Yeomans, Comets, 353; Crovisier and Encrenaz, Comet Science, 67.
121 Yeomans defi
nes an asteroid (minor planet) as “an interplanetary body that formed without appreciable ice content and thus never had, or can have, cometary activity” (Yeomans, Comets, 352).
122 Stephen J. Edberg and David H. Levy, Observing Comets, Asteroids, Meteors, and the Zodiacal Light (Cambridge: Cambridge University Press, 1994), 29.
123 Brian G. Marsden and Zdenek Sekanina, “Comets and Nongravitational Forces. VI. Periodic Comet Encke 1786–1971,” Astronomical Journal 79 (1974): 418; Fred L. Whipple and S. E. Hamid, “A Search for Encke’s Comet in Ancient Chinese Records: A Progress Report,” in The Motion, Evolution of Orbits, and Origin of Comets, ed. Gleb Aleksandrovich Chebotarev, E. I. Kazimirchak-Polonskaia, and B. G. Marsden (Dordrecht, Netherlands: Reidel, 1972), 152–154.
124 Steel, Rogue Asteroids and Doomsday Comets, 27–28; D. J. Asher and S. V. M. Clube, “An Extraterrestrial Influence during the Current Glacial-Interglacial,” Quarterly Journal of the Royal Astronomical Society 34 (1993): 489.
125 Jenniskens, Meteor Showers, 126.
126 See Brandt and Chapman, Introduction to Comets, 67; and Crovisier and Encrenaz, Comet Science, 17. Imagine a tablet computer laptop with a swivel screen and an oval piece of paper placed over the screen, affixed to it at one point in the center of the bottom of the screen. The keyboard is resting on the horizontal level, which represents the ecliptic plane on which Earth orbits the Sun. When you open the laptop and lift the screen to a certain angle, whether 45 degrees, 90 degrees, or 135 degrees, you are changing the screen’s inclination. When you then turn the swivel screen around, it represents the changing of the longitude of the ascending node. Now twist the picture affixed to the screen around on its pivot—this represents changing the argument of perihelion. Now, suspending reality for a moment, imagine that the screen is monstrous, extending long in every direction, and that the similarly massive picture affixed to the screen is a giant oval. The longer the oval, the higher the eccentricity is; the more circular it is, the lower the eccentricity. The pivot point stands for the Sun. The point of the oval that is closest to the pivot represents perihelion, and the distance between them corresponds to the perihelion distance. Finally, if you run your finger along the edge of the oval, the moment when your finger (symbolizing the comet) is nearest the pivot (signifying the Sun) denotes the time of perihelion.
127 Starry Night® Pro 6.4.3.
128 Redshift 7, United Soft Media Verlag GmbH, Thomas-Wimmer-Ring 11, D-80539 Munich, Germany, http://www.redshift-live.com.
129 Project Pluto, Guide 9.0, 168 Ridge Road, Bowdoinham, ME 04008, http://www.projectpluto.com.
130 Schmude, Comets and How to Observe Them, 8.
131 Cf. Seargent, Comets: Vagabonds of Space, 85.
132 Data from NASA’s JPL Small-Body Database Browser, http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Hale-Bopp (accessed May 3, 2014). Hale-Bopp passed within 0.77 AU of Jupiter in April 1996, and this altered its path.
133 Whipple, Mystery of Comets, 149.
134 Schmude, Comets and How to Observe Them, 25–26. On other nongravitational factors, see Donald K. Yeomans and Paul W. Chodas, “Predicting Close Approaches of Asteroids and Comets to Earth,” in Hazards Due to Comets and Asteroids, ed. T. Gehrels (Tucson: University of Arizona Press, 1995), 241.
135 Jenniskens, Meteor Showers, 378; cf. Clube and Napier, Cosmic Winter, 140.
136 Jenniskens, Meteor Showers, 29.
137 See Brandt and Chapman, Introduction to Comets, 331.
138 See Jenniskens, Meteor Showers, 81–86, 172–200; Esko Lyytinen and Peter Jenniskens, “Meteor Outbursts from Long-Period Comet Dust Trails,” Icarus 162 (2003): 443–452.
139 David Hughes as cited by Burnham, Great Comets, 51 (see also Burnham’s comments on p. 70); John. E. Bortle, “Great Comets in History,” Sky and Telescope 93.1 (1997): 44; Seargent, Greatest Comets, vii, 78; Donald K. Yeomans, “Cometary Astronomy,” in History of Astronomy: An Encyclopedia, ed. John Lankford (New York: Routledge, 1996), 159 (and “Great Comets in History,” http://ssd.jpl.nasa.gov/?great_comets [posted April 2007]).
140 Mobberley, Hunting and Imaging Comets, 46.
141 Isaac Asimov, Asimov’s Guide to Halley’s Comet: The Awesome Story of Comets (New York: Walker, 1985), 56.
142 Hermann Hunger, F. Richard Stephenson, C. B. F. Walker, and K. K. C. Yau, Halley’s Comet in History (London: British Museum, 1985), 10.
143 F. Richard Stephenson, “The Ancient History of Halley’s Comet,” in Standing on the Shoulders of Giants, ed. Norman Thrower (Berkeley: University of California Press, 1990), 243, who mentions private correspondence with Hermann Hunger on this issue.
144 Ibid., 245–248; Hunger et al., Halley’s Comet in History, 18–40.
145 Stephenson, “Ancient History of Halley’s Comet,” 244.
146 Hunger et al., Halley’s Comet in History, 10.
147 Information concerning each of these cometary observations from Babylon can be found in Kronk, Cometography, 1:7–18. On the 164 BC and 87 BC comets (Halley’s Comet), see Hunger et al., Halley’s Comet in History, 18–40.
148 Stephenson, “Ancient History of Halley’s Comet,” 244.
149 Ibid.
150 Ibid.
151 Ibid.
152 Hunger et al., Halley’s Comet in History, 18.
153 Ibid., 53.
154 The Han shu, or The History of the Former Han Dynasty, was composed in the late first and early second century AD and completed in AD 111.
155 See David W. Hughes, “The Magnitude Distribution, Perihelion Distribution, and Flux of Long-Period Comets,” Monthly Notices of the Royal Astronomical Society 326 (2001): 515–516. Also Thomas John York, “The Reliability of Early East Asian Astronomical Records” (PhD thesis, Durham University, 2003), 64, 67–68, 78, 121; available online at http://etheses.dur.ac.uk/3080/. See my appendix 1 on the Chinese records.
156 John T. Ramsey and A. Lewis Licht, The Comet of 44 B.C. and Caesar’s Funeral Games (Oxford: Oxford University Press, 1997), 109.
157 Ibid., 116, also 73, 109; A. Lewis Licht, “The Rate of Naked-Eye Comets from 101 BC to 1970 AD,” Icarus 137 (1999): 355–356.
158 Ramsey and Licht, Comet of 44 B.C., 116.
159 David W. Hughes, “Early Long-Period Comets: Their Discovery and Flux,” Monthly Notices of the Royal Astronomical Society 339 (2003): 1103–1110. He notes that while no single nation’s astronomers ever actually recorded quite this many, the combined records of astronomers in the Far East, the Middle East, North Africa, and Europe between AD 1335 and 1600 totaled about 75 per century (pp. 1103, 1109). Between AD 1 and 1600 the total number of comet records per century increased from 37 (AD 100–810) to 53 (AD 810–1355) to 75 (AD 1355–1600) (pp. 1106–1107). Hughes concludes that the relatively low number of cometary records per century before AD 500 is evidence that the data that survives from that early period is incomplete (1108).
160 Ramsey and Licht, Comet of 44 B.C., 111–112.
161 Meteorologica, esp. parts 4–7.
162 My translation.
163 Translation from Suetonius, The Lives of the Twelve Caesars, vol. 2, ed. and trans. J. C. Rolfe, rev. ed., Loeb Classical Library (Cambridge, MA: Harvard University Press, 1914), 151.
164 My translation.
165 Ptolemy, Tetrabiblos: Or Quadripartite, trans. Frank Egleston Robbins, Loeb Classical Library (Cambridge, MA: Harvard University Press, 1940), 193, 195:
We must observe . . . for the prediction of general conditions, the comets which appear either at the time of the eclipse or at any time whatever; for instance, the so-called “beams,” “trumpets,” “jars,” and the like, for these naturally produce the effects peculiar to Mars and to Mercury—wars, hot weather, disturbed conditions, and the accompaniments of these; and they show, through the parts of the zodiac in which their heads appear and through the directions in which the shapes of their tails point, the regions upon which the misfortunes impend.
Through the formations, as it were, of their heads, they indicate the kind of the event and the class upon which the misfortune will take effect; through the time which they last, the duration of the events; and through their position relative to the sun likewise their beginning; for in general their appearance in the orient [the east] betokens rapidly approaching events and in the occident [west] those that approach more slowly.
See Yeomans, Comets, 14–16, on Ptolemy’s view of comets.
166 Sara Schechner Genuth, Comets, Popular Culture, and the Birth of Modern Cosmology (Princeton, NJ: Princeton University Press, 1997), 55, speaking of seventeenth-century Western astrologers, comments that “There was a lot of latitude in the iconographic technique, and the astrologer could put a positive spin on his predictions if he was so inclined.” Her statement applies equally to ancient astrologers.
Chapter 6: “A Stranger midst the Orbs of Light”
1 One prominent recent advocate of the comet hypothesis is the host of the BBC series Wonders of the Solar System and Wonders of the Universe and author of the accompanying books, Brian Cox. His opinion on the matter was given in the documentary “Star of Bethlehem: Behind the Myth,” produced by Atlantic Productions in London and shown on the BBC in the UK in 2008 and on ABC in Australia in 2009. I am grateful to Atlantic for generously sending me a complimentary DVD copy of the production.
2 My translation of the Greek text in Emile de Strycker, La forme la plus ancienne du Protevangile de Jacques (Brussels: Société des Bollandistes, 1961), 168–170.
3 Roberta J. M. Olson and Jay M. Pasachoff, “New Information on Comet Halley as Depicted by Giotto Di Bondone and Other Western Artists,” in 20th ESLAB Symposium on the Exploration of Halley’s Comet: Proceedings of the International Symposium, Heidelberg, Germany, 27–31 October, vol. 3 (Noordwijk, Netherlands: European Space Agency, 1986), C207.
4 The standard rendering of English translations (e.g., Alexander Roberts, James Donaldson, and A. Cleveland Coxe, The Ante-Nicene Fathers Vol. IV: Translations of the Writings of the Fathers Down to A.D. 325 [New York: Scribner, 1926], 422; Henry Chadwick, Origen: Contra Celsum [Cambridge: Cambridge University Press, 1965], 53–54) at this point, “meteors,” is clearly inappropriate. After all, Origen makes it clear in the subsequent context that he is speaking only of comets, and it is well known and established that cometary apparitions may take a multitude of forms—see Carl Sagan and Ann Druyan, Comet (New York: Pocket Books, 1986), 157–187. “Beam [of wood]” here (the most common meaning of the Greek term and of its Latin rendering) is evidently a type of comet—one with a long, straight tail. Meteors do not have anything like the same multiplicity of forms.
