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Discovered by Jean-Louis Pons
William Robert Brooks
Discovery date July 12, 1812
1812; 1884 I; 1954 VII
Orbital characteristics A
Epoch 1954-Sep-15[1]
Aphelion 33.468 AU
Perihelion 0.77366 AU
Semi-major axis 17.1212 AU
Eccentricity 0.95481
Orbital period 70.85 yr
Inclination 74.176°
Last perihelion May 22, 1954[2]
January 25, 1884
September 15, 1812
Next perihelion April 21, 2024[2]

12P/Pons–Brooks is a periodic comet with an orbital period of 71 years. It fits the classical definition of a Halley-type comet with (20 years < period < 200 years).[1] Its next closest approach to Earth is in 2024.[2]

As of December 2015 12P/Pons–Brooks has not been identified with any meteor-shower clouds.[3]


A comet was observed from Korea from 10 April to June 1313 CE.[4] Over in China, "in the reign of Jin Tsung, the 2nd year of the epoch Hwang King, 3rd moon, day Ting Wei, a comet appeared in the eastern part of S. D. Tsing". This date is calculated to 13 April 1313. The eastern part of the "S. D. Tsing" corresponds to the stars Mebsuta and Alhena in Gemini: about right-ascension 6h and declination 20°.[5] In Vietnam "during the third month (of the twenty-first year of the Hu'ng-long reign-period) (28 March to 25 April 1313) a hui comet was seen in the west".[6]

Koreans observed "another" comet over 20 March - 22 May 1668.[7] This one started from Pisces (~RA 1h, Dec. 30°) and traveled southwest across Cetus toward Eridanus (~RA 5h, Dec. -10°). Again in Vietnam, "on a ky-su'u day of the first month, in the spring of the sixth year (of the Canh-tri reign-period), a mau-than year (8 March 1668) a 'Celestial Flail' star appeared in the northwest direction, measuring five feet and resembling a hui comet'";[8] this is further noted "in the Astronomical Chapters of the Ch'ing Shi Kao" in China.[9] A comet was also recorded beginning early March 1668 by Europeans; this appeared in the "Whale" constellation today known as Cetus and likewise traveled to Eridanus.[10][11]

In the West a third observation was logged on July 12, 1812, by Jean-Louis Pons. Independently, this comet was later found by Vincent Wisniewski on August 1, and Alexis Bouvard on August 2 the same year. At the time no-one had brought these three observations together.

In 1883 a "fourth" comet was accidentally discovered by William Robert Brooks and later identified as the same object as the 1812. Shortly after its initial discovery it was found to have an orbital period of about 70 years with an error of about 5 years. Johann Franz Encke determined a definitive orbit with a period of 70.68 years. This orbit was used to generate an ephemeris for the 1883 return, but searches were unsuccessful, until it was rediscovered by Brooks. In 2007, Korean astronomers So-Yeon Park and Jongchul Chae identified Pons-Brooks with the observations of 1313 and of 1668.[12]


Libration is locked at a 6:1 resonance with Jupiter.[13] The Tisserand invariant with respect to Jupiter (J) is 0.60.[14]

Orbital evolution... from 1585 to 2406. Top: comet's trajectories in a frame centred on Jupiter and rotating with it around the Sun. Centre: plots of the osculating period (in units of Jupiter's period); the plots extend from -0.5 to +0.5 around the exact resonance. Bottom: polar diagram of the osculating period (radius vectors) and the heliocentric elongation of Jupiter from the comet (at perihelion of the latter, position angles).[15]

With a steep orbital inclination of 74.2° this comet does not spend a lot of time near the ecliptic. The Jet Propulsion Laboratory's (JPL) website shows that between the years 1900 and 2200, that the comet was and will be most significantly perturbed by Saturn on July 29, 1957. At that point it passed within 1.6AU of the giant planet's influence; even this approach had negligible effect.[16] The comet's orbit appears to be stable between 1740 and 2167, with no strong perturbations by any of the planets.[17][18]

Prehistorical speculation[edit]

Carl Sagan suggested 12P as the spectacular comet seen by the Chinese in 1486 BCE which, according to historical researcher Graham Phillips, might have inspired the rise of a number of new religions around the world[19]


  1. ^ a b "12P/Pons-Brooks". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 1000068. Retrieved 2011-10-17. 
  2. ^ a b c 12P/Pons-Brooks – Seiichi Yoshida @ aerith.net
  3. ^ Dušan Tomko (1 December 2015). "Modeling of a theoretical stream of comet 12P/Pons-Brooks". Planetary and Space Science. 118: 35–37. 
  4. ^ So-Yeon Park; Jongchul Chae (2007). "Analysis of Korean Historical Comet Records". Publications of the Korean Astronomical Society. 22: 151–68. , 163-4 #4.3.2, fig. 18.
  5. ^ John Williams (1871). Observations of Comets from B. C. 611 to A. D. 1640: Extracted from the Chinese Annals. Translated, with introductury Remarks, and Appendix, comprising the Tables necessary for reducing Chinese Time to European reckoning and Chinese celestial Atlas. Strangways and Walden. , 68 #284. This takes Yuan-era events from "the supplement to [Ma Twan Lin's encyclopaedia] and the She Ke".
  6. ^ H Peng-Yoke (1964). "Natural Phenomena Recorded in the Đai-Viêt Su'-ky Toan-Thu', an Early Annamese Historical Source". Journal of the American Oriental Society: 127–149. , 132 #19 from the Ban-Ky Toan-thu' ed. Ngo Si-Lien 1479, ch. 6.
  7. ^ So-Yeon Park and Jongchul Chae, fig. 17.
  8. ^ H Peng-Yoke, 134 #44 from Ban-ky Thu'c-bien Truy-gia.
  9. ^ Ibidem.
  10. ^ P. Valentin Estancel (1674). "Observations Concerning the Comet That Was Seen in Brasil, An. 1668 in March". Phil. Trans. 9: 91–93. 
  11. ^ Lynn, W. T. (1882). "The Comet of 1668". The Observatory. 5: 329–331. 
  12. ^ So-Yeon Park and Jongchul Chae.
  13. ^ A. Carusi, L. Kresak, E. Perozzi, G.B. Valsecchi (1987). "High-order librations of Halley-type comets". Astronomy and Astrophysics. 187: 899–905.  , 900.
  14. ^ Ibidem, 899.
  15. ^ A. Carusi, L. Kresak, E. Perozzi, G.B. Valsecchi. Fig. 5. Text, 902; graph, 903a
  16. ^ "12P/Pons-Brooks close-approach data". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 1000068. Retrieved 2009-05-06. 
  17. ^ Kronk, Gary W. (2001–2005). "12P/Pons-Brooks". Archived from the original on 2009-05-09. Retrieved 2009-05-07.  (Cometography Home Page)
  18. ^ A. Carusi, L. Kresak, E. Perozzi, G.B. Valsecchi, 905.
  19. ^ Graham Phillips: The End of Eden

External links[edit]

Periodic comets (by number)
12P/Pons–Brooks Next