Decan

File:Astronomical Ceiling, Tomb of Senenmut MET DT207429.jpg showing various decans, as well as the personified representations of stars and constellations]]

Decans first appeared in the 10th Dynasty (2100 BCE) on coffin lids.{{sfn|Symons|2013}} The sequence of these star patterns began with Sothis (Sirius), and each decan contained a set of stars and corresponding divinities. As measures of time, the rising and setting of decans marked 'hours' and groups of 10 days which comprised an Egyptian year. The ancient Book of Nut covers the subject of the decans.

There were 36 decans (36 × 10 = 360 days),{{sfn|von Bomhard|1999|p=51}} plus five added days to compose the 365 days of a solar based year. Decans measure sidereal time and the solar year is six hours longer; the Sothic and solar years in the Egyptian calendar realign every 1460 years. Decans represented on coffins from later dynasties (such as King Seti I) compared with earlier decan images demonstrate the Sothic-solar shift.

According to Sarah Symons:

Although we know the names of the decans, and in some cases can translate the names (ḥry-ỉb wỉꜣ means 'in the centre of the boat') the locations of the decanal stars and their relationships to modern star names and constellations are not known. This is due to many factors, but key problems are the uncertainty surrounding the observation methods used to develop and populate the diagonal star tables, and the criteria used to select decans (brightness, position, relationship with other stars, and so on).{{sfn|Symons|2007}}

These predictable heliacal re-appearances by the decans were eventually used by the Egyptians to mark the divisions of their annual solar calendar. Thus the heliacal rising of Sirius marked the annual flooding of the Nile.

This method led to a system of 12 daytime hours and 12 nighttime hours, varying in length according to the season. Later,{{when|date=September 2021}} a system of 24 "equinoctial" hours was used.{{sfnm|1a1=Neugebauer|1y=1983|1pp=205–209|2a1=Neugebauer|2y=1969|2pp=81–88}} After Hellenistic astrology arose in Alexandria, recorded principally in the work of Claudius Ptolemy and Vettius Valens, various systems attributing symbolic significance to decans arose and linked these to the "wandering stars" (Mercury, Venus, Mars, Jupiter and Saturn) and the "Lights": (Sun and Moon).{{sfn|van der Waerden|1949}} Decans were connected, for example, with the winds, the four directions, the sect (day or night,) male and female, as well as the four humours (elements;) also these were hermetically considered linked with various diseases and with the timing for the engraving of talismans for curing them;{{sfn|Ruelle|1908|p=247}} with decanic "faces" (or "phases"), a system where three decans are assigned to each zodiacal sign, each covering 10° of the zodiac, and each ruled by a planetary ruler (see Decan (astrology)); and correlated with astrological signs.{{sfn|Julius Firmicus Maternus|1968|loc=IV/22}}

Decans are named in various Greco-Egyptian sources, many Hermetic writings, the Testament of Solomon,{{harvnb|Gundel|1936|pp=77-81}}. the Tabula Aristobuli (Codex Palatinus) attributed to Aristobulus of Paneas,{{harvnb|Gundel|1936|pp=406-408}}. and the writings of Julius Firmicus Maternus, Cosmas of Maiuma, Joseph Justus Scaliger, and Athanasius Kircher.

Images of the decans are described in Hermetic writings, by the Indian astrologer Varāhamihira, in the Picatrix, and in Japanese writings.{{sfn|Gundel|1936|pp=223-225}} Varāhamihira's images of the decans was influenced by Greco-Egyptian, if not Hermetic, depictions of the decans by way of the Yavanajataka.{{sfn|Pingree|1963}} Their role in Japanese astrology may have derived from an earlier Chinese{{harvnb|Gundel|1936|pp=217-221}}. or Indian form{{sfn|Michio|2008}} possibly from adding the twelve animals of the Chinese zodiac to a list of twenty-four hour stars. They were most common between the Kamakura and Edo periods.{{sfn|Michio|2008}}

The first original decan position due to the precession in ancient times started at 0° of Cancer when the heliacal rising of Sirius (Egyptian Sepdet; Greco-Egyptian: Sothis) before sunrise marking the Egyptian New Year which fell at 0° of Leo at July 20 in the Julian calendar, that is July 22/23 on the Gregorian calendar.{{Citation needed|date=November 2016}}

{{main|Drekkana}}

In India, the division of the zodiac into 36 ten degree portions is called either the drekkana (drekkāṇa), the dreshkana (dreṣkāṇa), or the drikana (dṛkāṇa).Monier Williams Sanskrit Dictionary{{full citation needed|date=January 2024}}

The iconography and use of the drekkanas is mention earliest by Sphujidhvaja in Yavanajataka (269–270 CE), and given detailed treatment by Varahamihira in his Brihat-Samhita (550 CE). Modern scholars believe the decans were imported into India through the Greeks, who learned about them from the Egyptians.{{sfn|Pingree|1963}}

• Asterism (astronomy)
• Astronomical ceiling of Senemut Tomb
• Behenian fixed star
• Chinese zodiac
• Palazzo Schifanoia, Ferrara
• Worship of heavenly bodies

{{Reflist}}

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• {{cite book |title=Dekane und Dekansterbilder |first=Wilhelm |last=Gundel |publisher=J. J. Augustin |place=Glückstadt and Hamburg |year=1936 |lang=de}}
• {{cite book |author=Hermes Trismegistus |author-link=Hermes Trismegistus |editor-first=Robert |editor-last=Hand |editor-link=Robert Hand |title=Hermes: Liber Hermetis Part I and Part II |translator=Robert Zoller |place=Berkeley Springs, WV |publisher=Golden Hind Press |year=1993 |edition=1st |url=https://www.weiserantiquarian.com/pages/books/68073/hermes-trismegistus-robert-hand/hermes-liber-hermetis-part-i-and-part-ii-project-hindsight-latin-track-volume-ii-and-volume-iii?soldItem=true}}
• {{cite book |author=Julius Firmicus Maternus |author-link=Julius Firmicus Maternus |title=Matheseos libri VIII |editor1-first=W. |editor1-last=Kroll |editor2-first=F. |editor2-last=Skutsch |place=Stuttgart |publisher=Teubner |year=1968 |orig-year=336 |lang=la}} 2 vols.
• {{Cite book |title=The Oxford Handbook of Science and Medicine in the Classical World |isbn=978-0190878832 |last1=Keyser |first1=Paul |last2=Scarborough |first2=John |year=2018|publisher=Oxford University Press }}
• {{cite book |title=Oedipus Aegyptiacus |title-link=Oedipus Aegyptiacus |first=Athanasius |last=Kircher |author-link=Athanasius Kircher |location=Italy |publisher=Vitale Mascardi |year=1652 |lang=la}}
• {{cite journal |title=Bukkyō tenbugaku-senseijutsu no zuzō gakuteki junmen: sanjū rokkin to Dekan |first=Yano |last=Michio |journal=Dōshisha daigaku rikō kenkyū hōkoku |volume=48 |number=4 |year=2008 |pages=1–6 |lang=ja}}
• {{Cite book |edition=2nd |publisher=Dover Publications |last=Neugebauer |first=Otto |author-link=Otto E. Neugebauer |title=The Exact Sciences in Antiquity |orig-year=1957 |year=1969 |isbn=978-0-486-22332-2}}
• {{cite book |last1=Neugebauer |first1=Otto |title=Astronomy and History: Selected Essays |year=1983 |orig-year=1955 |publisher=Springer |location=New York |isbn=978-0-387-90844-1 |pages=205–209 |chapter=The Egyptian 'Decans' |doi=10.1007/978-1-4612-5559-8}}
• {{cite journal |last1=Pingree |first1=David |title=The Indian Iconography of the decans and Horas |journal=Journal of the Warburg and Courtauld Institutes |volume=26 |issue=3/4 |year=1963 |pages=223–254 |jstor=750493 |doi=10.2307/750493 |s2cid=194974629 |author-link1=David Pingree}}
• {{cite journal |title=The Astral Myth of Osiris: the Decans of Taurus and Libra |first=Gyula |last=Priskin |journal=ENiM |url=http://www.enim-egyptologie.fr/revue/2016/7/Priskin_ENiM9_p79-111.pdf |number=9 |year=2016 |pages=79–111 |access-date=2021-07-08}}
• {{cite book |author=Ptolemy |author-link=Ptolemy |title=Tetrabiblos |volume=Book I Part 18 |translator=Frank Egleston Robbins |year=1940 |location=Cambridge, MA |publisher=Loeb}}
• {{cite journal |title=Hermès Trismégiste: Le Livré Sacre sur les Décans: Texte, variantes et traduction française |first=C. E. |last=Ruelle |journal=Revue de Philologie |volume=32 |number=4 |date=October 1908 |pages=247–277 |lang=fr}}
• {{cite book |last=Symons |first=S. L. |chapter-url=http://www2.le.ac.uk/Members/sls25/paperstarsyear |chapter=A Star's Year: The Annual Cycle in the Ancient Egyptian Sky |archive-url=https://web.archive.org/web/20130615213439/http://www2.le.ac.uk/Members/sls25/paperstarsyear/ |archive-date=2013-06-15 |editor-last=Steele |editor-first=J. M. |year=2007 |title=Calendars and Years: Astronomy and Time in the Ancient World |publisher=Oxbow Books |place=Oxford |isbn=978-1842173022 |pages=1–33}}
• {{cite book |last=Symons |first=S. L. |display-authors=etal |year=2013 |title=Ancient Egyptian Astronomy |type=Online database |chapter-url=http://aea.physics.mcmaster.ca/index.php/en/database/diagonal-star-tables |chapter=Diagonal Star Tables}}
• {{cite journal |last1=van der Waerden |first1=B. L. |author-link1=Bartel Leendert van der Waerden |title=Babylonian Astronomy. II. The Thirty-Six Stars |journal=Journal of Near Eastern Studies |volume=8 |issue=1 |pages=6–26 |date=January 1949 |jstor=542436 |quote=The property of the Chaldean Decans that one of them rose every ten days made them fit to be assimilated to the Egyptian decans. This assimilation was performed in the decan lists of Hellenistic astrology. |doi=10.1086/370901 |s2cid=222443741}}
• {{cite book |last=von Bomhard |first=Anna-Sophie |title=The Egyptian Calendar: A Work for Eternity |place=London |publisher=Periplus |year=1999}}

{{refend}}

{{refbegin|2|indent=yes}}

• {{cite book |first=Paul |last=Christian |year=1969 |orig-year=1870 |chapter-url=https://archive.org/details/historypracticeo01chri/page/476/mode/2up |chapter=The Thirty-Six Decans |title=The History and Practice of Magic |publisher=Citadel |pages=476–478 }}
• {{cite book|last1=Symons|first1=Sarah|editor1-last=Ruggles|editor1-first=Clive L.N.|title=Handbook of Archaeoastronomy and Ethnoastronomy|date=2014|publisher=Springer|location=New York|isbn=978-1-4614-6140-1|pages=1495–1500|chapter=Egyptian 'Star Clocks'}}

{{refend}}

• [http://aea.physics.mcmaster.ca/ Ancient Egyptian Astronomy Database] (Symons, Cockcroft, Bettencourt & Koykka, 2013)
• [http://ib205.tripod.com/decans.html Egypt Astronomy/Astrology: The decans]

Category:Asterisms (astronomy)

Category:Constellations

Category:Ancient astronomy

Category:Technical factors of Chinese astrology

Category:Technical factors of Western astrology

Category:Egyptian calendar