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Available in 17 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-17" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">17 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AF%D9%88%D8%B1%D8%A9_%D8%B3%D9%88%D8%AB%D9%8A%D8%A9" title="دورة سوثية – Arabic" lang="ar" hreflang="ar" data-title="دورة سوثية" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Ciclu_sot%C3%ADaco" title="Ciclu sotíaco – Asturian" lang="ast" hreflang="ast" data-title="Ciclu sotíaco" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/S%C3%B3thick%C3%A1_perioda" title="Sóthická perioda – Czech" lang="cs" hreflang="cs" data-title="Sóthická perioda" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://de.wikipedia.org/wiki/Sothis-Zyklus" title="Sothis-Zyklus – German" lang="de" hreflang="de" data-title="Sothis-Zyklus" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Ciclo_sot%C3%ADaco" title="Ciclo sotíaco – Spanish" lang="es" hreflang="es" data-title="Ciclo sotíaco" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Lever_h%C3%A9liaque_de_Sirius" title="Lever héliaque de Sirius – French" lang="fr" hreflang="fr" data-title="Lever héliaque de Sirius" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Ciclo_sotiaco" title="Ciclo sotiaco – Italian" lang="it" hreflang="it" data-title="Ciclo sotiaco" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Cyclus_Sothicus" title="Cyclus Sothicus – Latin" lang="la" hreflang="la" data-title="Cyclus Sothicus" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Sothisperiode" title="Sothisperiode – Dutch" lang="nl" hreflang="nl" data-title="Sothisperiode" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%82%BD%E3%83%86%E3%82%A3%E3%82%B9%E5%91%A8%E6%9C%9F" title="ソティス周期 – Japanese" lang="ja" hreflang="ja" data-title="ソティス周期" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Datowanie_sotisowe" title="Datowanie sotisowe – Polish" lang="pl" hreflang="pl" data-title="Datowanie sotisowe" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Soti%C4%8Dki_ciklus" title="Sotički ciklus – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Sotički ciklus" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Sothis-jakso" title="Sothis-jakso – Finnish" lang="fi" hreflang="fi" data-title="Sothis-jakso" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Sotik_d%C3%B6ng%C3%BC" title="Sotik döngü – Turkish" lang="tr" hreflang="tr" data-title="Sotik döngü" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%AF%D9%88%D8%B1_%D8%B4%D8%B9%D8%B1%DB%8C%D9%B0_%DB%8C%D9%85%D8%A7%D9%86%DB%8C" title="دور شعریٰ یمانی – Urdu" lang="ur" hreflang="ur" data-title="دور شعریٰ یمانی" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Chu_k%E1%BB%B3_Sothic" title="Chu kỳ Sothic – Vietnamese" lang="vi" hreflang="vi" data-title="Chu kỳ Sothic" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%A4%A9%E7%8B%BC%E5%91%A8" title="天狼周 – Chinese" lang="zh" hreflang="zh" data-title="天狼周" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1749234#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu 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</div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">1460 year calendar cycle of ancient Egypt</div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Hubble_heic0206j.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Hubble_heic0206j.jpg/250px-Hubble_heic0206j.jpg" decoding="async" width="200" height="139" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Hubble_heic0206j.jpg/330px-Hubble_heic0206j.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Hubble_heic0206j.jpg/500px-Hubble_heic0206j.jpg 2x" data-file-width="1280" data-file-height="889" /></a><figcaption><a href="/wiki/Sirius_(star)" class="mw-redirect" title="Sirius (star)">Sirius</a> (<i>bottom</i>) and <a href="/wiki/Orion_(constellation)" title="Orion (constellation)">Orion</a> (<i>right</i>). The <a href="/wiki/Winter_Triangle" title="Winter Triangle">Winter Triangle</a> is formed from the three brightest stars in the northern winter sky: Sirius, <a href="/wiki/Betelgeuse" title="Betelgeuse">Betelgeuse</a> (<i>top right</i>), and <a href="/wiki/Procyon" title="Procyon">Procyon</a> (<i>top left</i>).</figcaption></figure> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:CanisMajorCC.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c7/CanisMajorCC.jpg/200px-CanisMajorCC.jpg" decoding="async" width="200" height="300" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c7/CanisMajorCC.jpg/300px-CanisMajorCC.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c7/CanisMajorCC.jpg/400px-CanisMajorCC.jpg 2x" data-file-width="426" data-file-height="640" /></a><figcaption>Sirius as the brightest star in the <a href="/wiki/Asterism_(astronomy)" title="Asterism (astronomy)">constellation</a> <a href="/wiki/Canis_Major" title="Canis Major">Canis Major</a> as observed from the Earth (lines added for clarity).</figcaption></figure> <p>The <b>Sothic cycle</b> or <b>Canicular period</b> is a period of 1,461 <a href="/wiki/Egyptian_civil_year" class="mw-redirect" title="Egyptian civil year">Egyptian civil years</a> of 365 days each or 1,460 <a href="/wiki/Julian_calendar" title="Julian calendar">Julian years</a> averaging <style data-mw-deduplicate="TemplateStyles:r1154941027">.mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style><span class="frac">365<span class="sr-only">+</span><span class="num">1</span>⁄<span class="den">4</span></span> days each. During a Sothic cycle, the 365-day year loses enough time that the start of its year once again coincides with the <a href="/wiki/Heliacal_rising" title="Heliacal rising">heliacal rising</a> of the star <a href="/wiki/Sirius" title="Sirius">Sirius</a> (<a href="/wiki/Ancient_Egyptian_language" class="mw-redirect" title="Ancient Egyptian language">Ancient Egyptian</a>: <i lang="egy"><a href="https://en.wiktionary.org/wiki/spdt" class="extiw" title="wikt:spdt">spdt</a></i> or <span title="Ancient Egyptian-language text"><i lang="egy-Latn"><a href="/wiki/Sopdet" title="Sopdet">Sopdet</a></i></span>, 'Triangle'; <a href="/wiki/Ancient_Greek_language" class="mw-redirect" title="Ancient Greek language">Ancient Greek</a>: <span lang="grc">Σῶθις</span>, <span title="Ancient Greek (to 1453)-language text"><i lang="grc-Latn">Sō̂this</i></span>) on 19 July in the <a href="/wiki/Julian_calendar" title="Julian calendar">Julian calendar</a>.<sup id="cite_ref-lavia_1-0" class="reference"><a href="#cite_note-lavia-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> It is an important aspect of <a href="/wiki/Egyptology" title="Egyptology">Egyptology</a>, particularly with regard to reconstructions of the <a href="/wiki/Egyptian_calendar" title="Egyptian calendar">Egyptian calendar</a> and its history. <a href="/wiki/Egyptian_astronomy" title="Egyptian astronomy">Astronomical records</a> of this displacement may have been responsible for the later establishment of the more accurate <a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a> and <a href="/wiki/Alexandrian_calendar" class="mw-redirect" title="Alexandrian calendar">Alexandrian calendars</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Mechanics">Mechanics</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=1" title="Edit section: Mechanics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/Ancient_Egypt" title="Ancient Egypt">ancient Egyptian</a> <a href="/wiki/Egyptian_calendar" title="Egyptian calendar">civil year</a>, its holidays, and religious records reflect its apparent establishment at a point when the <a href="/wiki/Heliacal_rising" title="Heliacal rising">return</a> of the bright star <a href="/wiki/Sirius_(star)" class="mw-redirect" title="Sirius (star)">Sirius</a> to the night sky was considered to herald the annual <a href="/wiki/Flooding_of_the_Nile" title="Flooding of the Nile">flooding of the Nile</a>.<sup id="cite_ref-teacosy_3-0" class="reference"><a href="#cite_note-teacosy-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> However, because the civil calendar was exactly 365 days long and did not incorporate <a href="/wiki/Leap_year" title="Leap year">leap years</a> until 22 BCE, its months "wandered" backwards through the <a href="/wiki/Solar_year" class="mw-redirect" title="Solar year">solar year</a> at the rate of about one day in every four years. This almost exactly corresponded to its displacement against the <b>Sothic year</b> as well. (The Sothic year is about a minute longer than a <a href="/wiki/Julian_year_(calendar)" class="mw-redirect" title="Julian year (calendar)">Julian year</a>.)<sup id="cite_ref-teacosy_3-1" class="reference"><a href="#cite_note-teacosy-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Sidereal_year" title="Sidereal year">sidereal year</a> of 365.25636 days is valid only for stars on the <a href="/wiki/Ecliptic" title="Ecliptic">ecliptic</a> (the apparent path of the <a href="/wiki/Sun" title="Sun">Sun</a> across the sky) and having no <a href="/wiki/Proper_motion" title="Proper motion">proper motion</a>, whereas Sirius's displacement ~40° below the ecliptic, its proper motion, and the wobbling of the <a href="/wiki/Celestial_equator" title="Celestial equator">celestial equator</a> cause the period between its <a href="/wiki/Heliacal_rising" title="Heliacal rising">heliacal risings</a> to be almost exactly 365.25 days long instead. This steady loss of one relative day every four years over the course of the 365-day calendar meant that the "wandering" day would return to its original place relative to the solar and Sothic year after precisely 1461 Egyptian civil years or 1460 Julian years.<sup id="cite_ref-lavia_1-1" class="reference"><a href="#cite_note-lavia-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Discovery">Discovery</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=2" title="Edit section: Discovery"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>This calendar cycle was well known in antiquity. Censorinus described it in his book <i>De Die Natale</i>, in CE 238, and stated that the cycle had renewed 100 years earlier on the 12th of August. In the ninth century, Syncellus epitomized the Sothic Cycle in the "Old Egyptian Chronicle." Isaac Cullimore, an early Egyptologist and member of the Royal Society, published a discourse on it in 1833 in which he was the first to suggest that Censorinus had fudged the terminus date, and that it was more likely to fall in CE 136. He also computed the likely date of its invention as being around 1600 BCE. </p><p>In 1904, seven decades after Cullimore, <a href="/wiki/Eduard_Meyer" title="Eduard Meyer">Eduard Meyer</a> carefully combed known Egyptian inscriptions and written materials to find any mention of the calendar dates when Sirius rose at dawn. He found six of them, on which the dates of much of conventional <a href="/wiki/Egyptian_chronology" title="Egyptian chronology">Egyptian chronology</a> are based. A heliacal rise of Sirius was recorded by <a href="/wiki/Censorinus" title="Censorinus">Censorinus</a> as having happened on the Egyptian New Year's Day between 139 CE and 142 CE.<sup id="cite_ref-Kitchen_4-0" class="reference"><a href="#cite_note-Kitchen-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>The record itself actually refers to 21 July 140 CE, but astronomical calculation definitely dates the heliacal rising at 20 July 139 CE, Julian. This correlates the Egyptian calendar to the <a href="/wiki/Julian_calendar" title="Julian calendar">Julian calendar</a>. A Julian leap day occurs in 140 CE, and so the new year on 1 <a href="/wiki/Thoth_(month)" class="mw-redirect" title="Thoth (month)">Thoth</a> is 20 July in 139 CE but it is 19 July for 140–142 CE. Thus <a href="/wiki/Eduard_Meyer" title="Eduard Meyer">Meyer</a> was able to compare the Egyptian civil calendar date on which Sirius was observed rising heliacally to the Julian calendar date on which Sirius <i>ought</i> to have risen, count the number of intercalary days needed, and determine how many years were between the beginning of a cycle and the observation. </p><p>To calculate a date astronomically, one also needs to know the place of observation, since the latitude of the observation changes the day when the heliacal rising of Sirius can be seen, and mislocating an observation can potentially throw off the resulting chronology by several decades.<sup id="cite_ref-Kitchen_4-1" class="reference"><a href="#cite_note-Kitchen-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Official observations are known to have been made at <a href="/wiki/Heliopolis_(Ancient_Egypt)" class="mw-redirect" title="Heliopolis (Ancient Egypt)">Heliopolis</a> (or <a href="/wiki/Memphis,_Egypt" title="Memphis, Egypt">Memphis</a>, near <a href="/wiki/Cairo" title="Cairo">Cairo</a>), <a href="/wiki/Thebes,_Egypt" title="Thebes, Egypt">Thebes</a>, and <a href="/wiki/Elephantine" title="Elephantine">Elephantine</a> (near <a href="/wiki/Aswan" title="Aswan">Aswan</a>),<sup id="cite_ref-teatime_5-0" class="reference"><a href="#cite_note-teatime-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> with the rising of Sirius observed at Cairo about 8 days after it is seen at Aswan.<sup id="cite_ref-teatime_5-1" class="reference"><a href="#cite_note-teatime-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Meyer concluded that the Egyptian civil calendar was created in <a href="/wiki/5th_millennium_BC" title="5th millennium BC">4241 BCE</a>.<sup id="cite_ref-Meyer_6-0" class="reference"><a href="#cite_note-Meyer-6"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Breasted_7-0" class="reference"><a href="#cite_note-Breasted-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Recent scholarship, however, has discredited that claim. Most scholars either move the observation upon which he based this forward by one cycle of Sirius, to 19 July 2781 BCE, or reject the assumption that the document on which Meyer relied indicates a rise of Sirius at all.<sup id="cite_ref-Grimal-1988_8-0" class="reference"><a href="#cite_note-Grimal-1988-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 52">: 52 </span></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Chronological_interpretation">Chronological interpretation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=3" title="Edit section: Chronological interpretation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Three specific observations of the heliacal rise of Sirius are extremely important for Egyptian chronology. The first is the aforementioned ivory tablet from the reign of <a href="/wiki/Djer" title="Djer">Djer</a> which supposedly indicates the beginning of a Sothic cycle, the rising of Sirius on the same day as the new year. If this does indicate the beginning of a Sothic cycle, it must date to about 17 July 2773 BCE.<sup id="cite_ref-Grimal-1988_8-1" class="reference"><a href="#cite_note-Grimal-1988-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 51">:  51 </span></sup> However, this date is too late for Djer's reign, so many scholars believe that it indicates a correlation between the rising of Sirius and the Egyptian <i>lunar</i> calendar, instead of the solar Egyptian civil calendar, which would render the tablet essentially devoid of chronological value.<sup id="cite_ref-Grimal-1988_8-2" class="reference"><a href="#cite_note-Grimal-1988-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 52">:  52 </span></sup> </p><p>Gautschy <i>et al</i>. (2017) claimed that a newly discovered Sothis date from the Old Kingdom and a subsequent astronomic study confirms the Sothic cycle model.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>The second observation is clearly a reference to a heliacal rising, and is believed to date to the seventh year of <a href="/wiki/Senusret_III" title="Senusret III">Senusret III</a>. This observation was almost certainly made at <a href="/wiki/Itj-Tawy" class="mw-redirect" title="Itj-Tawy">Itj-Tawy</a>, the Twelfth Dynasty capital, which would date the Twelfth Dynasty from 1963 to 1786 BCE.<sup id="cite_ref-Kitchen_4-2" class="reference"><a href="#cite_note-Kitchen-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> The Ramses or Turin Papyrus Canon says 213 years (1991–1778 BCE), <a href="/wiki/Richard_Anthony_Parker" title="Richard Anthony Parker">Parker</a> reduces it to 206 years (1991–1785 BCE), based on 17 July 1872 BCE as the Sothic date (120th year of 12th dynasty, a drift of 30 leap days). Prior to Parker's investigation of lunar dates, the 12th dynasty was placed as 213 years of 2007–1794 BCE interpreting the date 21 July 1888 BCE as the 120th year, and then for 2003–1790 BCE interpreting the date 20 July 1884 BCE as the 120th year. </p><p>The third observation was in the reign of <a href="/wiki/Amenhotep_I" title="Amenhotep I">Amenhotep I</a>, and, assuming it was made in Thebes, dates his reign between 1525 and 1504 BCE. If made in Memphis, Heliopolis, or some other Delta site instead, as a minority of scholars still argue, the entire chronology of the 18th Dynasty needs to be extended some 20 years.<sup id="cite_ref-Grimal-1988_8-3" class="reference"><a href="#cite_note-Grimal-1988-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 202">:  202 </span></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Observational_procedure_and_precession">Observational procedure and precession</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=4" title="Edit section: Observational procedure and precession"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Sothic cycle is a specific example of two cycles of differing length interacting to cycle together, here called a tertiary cycle. This is mathematically defined by the formula <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {1}{a}}+{\frac {1}{b}}={\frac {1}{t}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mi>a</mi> </mfrac> </mrow> <mo>+</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mi>b</mi> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mi>t</mi> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {1}{a}}+{\frac {1}{b}}={\frac {1}{t}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d958d6caf1213da7aaf1d4d44e4c3922b5352664" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:12.002ex; height:5.343ex;" alt="{\displaystyle {\frac {1}{a}}+{\frac {1}{b}}={\frac {1}{t}}}" /></span> or half the <a href="/wiki/Harmonic_mean" title="Harmonic mean">harmonic mean</a>. In the case of the Sothic cycle the two cycles are the Egyptian civil year and the Sothic year. </p><p>The Sothic year is the length of time for the star Sirius to visually return to the same position in relation to the sun. Star years measured in this way vary due to <a href="/wiki/Axial_precession" title="Axial precession">axial precession</a>,<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> the movement of the Earth's axis in relation to the sun. </p><p>The length of time for a star to make a yearly path can be marked when it rises to a defined altitude above a local horizon at the time of sunrise. This altitude does not have to be the altitude of first possible visibility, nor the exact position observed. Throughout the year the star will rise to whatever altitude was chosen near the horizon approximately four minutes earlier each successive sunrise. Eventually the star will return to the same relative location at sunrise, regardless of the altitude chosen. This length of time can be called an <i>observational year</i>. Stars that reside close to the ecliptic or the ecliptic meridian will – on average – exhibit observational years close to the sidereal year of 365.2564 days. The ecliptic and the meridian cut the sky into four quadrants. The axis of the earth wobbles around slowly moving the observer and changing the observation of the event. If the axis swings the observer closer to the event its observational year will be shortened. Likewise, the observational year can be lengthened when the axis swings away from the observer. This depends upon which quadrant of the sky the phenomenon is observed. </p><p>The Sothic year is remarkable because its average duration happened to have been nearly exactly 365.25 days, in the early <span class="nowrap">4th millennium BCE<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup></span> before the unification of Egypt. The slow rate of change from this value is also of note. If observations and records could have been maintained during predynastic times the Sothic rise would optimally return to the same calendar day after 1461 calendar years. This value would drop to about 1456 calendar years by the Middle Kingdom. The value 1461 could also be maintained if the date of the Sothic rise were artificially maintained by moving the feast in celebration of this event one day every fourth year instead of rarely adjusting it according to observation. </p><p>It has been noticed, and the Sothic cycle confirms, that Sirius does not move retrograde across the sky, like other stars, a phenomenon widely known as the <a href="/wiki/Precession_of_the_equinox" class="mw-redirect" title="Precession of the equinox">precession of the equinox</a>: </p> <dl><dd>Sirius remains about the same distance from the equinoxes – and so from the solstices – throughout these many centuries, despite precession. — <a href="/wiki/Jed_Buchwald" title="Jed Buchwald">J.Z. Buchwald</a> (2003)<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></dd></dl> <p>For the same reason, the heliacal rising or zenith of Sirius does not slip through the calendar at the precession rate of about one day per 71.6 years as other stars do, but much slower.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> This remarkable stability within the solar year may be one reason that the Egyptians used it as a basis for their calendar. The coincidence of a heliacal rising of Sirius and the New Year reported by Censorinus occurred about 20 July, that is a month <i>after</i> the summer solstice. </p> <div class="mw-heading mw-heading2"><h2 id="Problems_and_criticisms">Problems and criticisms</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=5" title="Edit section: Problems and criticisms"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Determining the date of a heliacal rise of Sirius has been shown to be difficult, especially considering the need to know the exact latitude of the observation.<sup id="cite_ref-Kitchen_4-3" class="reference"><a href="#cite_note-Kitchen-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Another problem is that because the Egyptian calendar loses one day every four years, a heliacal rise will take place on the same day for four years in a row, and any observation of that rise can date to any of those four years, making the observation imprecise.<sup id="cite_ref-Kitchen_4-4" class="reference"><a href="#cite_note-Kitchen-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>A number of criticisms have been levelled against the reliability of dating by the Sothic cycle. Some are serious enough to be considered problematic. Firstly, none of the astronomical observations have dates that mention the specific pharaoh in whose reign they were observed, forcing Egyptologists to supply that information on the basis of a certain amount of informed speculation. Secondly, there is no information regarding the nature of the civil calendar throughout the course of Egyptian history, forcing Egyptologists to assume that it existed unchanged for thousands of years; the Egyptians would only have needed to carry out one calendar reform in a few thousand years for these calculations to be worthless. Other criticisms are not considered as problematic, e.g. there is no extant mention of the Sothic cycle in ancient Egyptian writing, which may simply be a result of it either being so obvious to Egyptians that it didn't merit mention, or to relevant texts being destroyed over time or still awaiting discovery. </p><p><a href="/wiki/Marc_Van_de_Mieroop" class="mw-redirect" title="Marc Van de Mieroop">Marc Van de Mieroop</a>, in his discussion of chronology and dating, does not mention the Sothic cycle at all, and asserts that the bulk of historians nowadays would consider that it is not possible to put forward exact dates earlier than the 8th century BCE.<sup id="cite_ref-vdMieroop-2015_14-0" class="reference"><a href="#cite_note-vdMieroop-2015-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>Some have recently claimed that the <a href="/wiki/Theran_eruption" class="mw-redirect" title="Theran eruption">Theran eruption</a> marks the beginning of the <a href="/wiki/Eighteenth_Dynasty_of_Egypt" title="Eighteenth Dynasty of Egypt">Eighteenth Dynasty</a>, due to Theran ash and pumice discovered in the ruins of <a href="/wiki/Avaris" title="Avaris">Avaris</a>, in layers that mark the end of the Hyksos era.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2014)">citation needed</span></a></i>]</sup> Because the evidence of <a href="/wiki/Dendrochronology" title="Dendrochronology">dendrochronologists</a> indicates the eruption took place in 1626 BCE, this has been taken to indicate that dating by the Sothic cycle is off by 50–80 years at the outset of the 18th Dynasty.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2014)">citation needed</span></a></i>]</sup> Claims that the Thera eruption is described on the <i><a href="/wiki/Tempest_Stele" title="Tempest Stele">Tempest Stele</a></i> of <a href="/wiki/Ahmose_I" title="Ahmose I">Ahmose I</a><sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> have been disputed by writers such as <a href="/wiki/Peter_James_(historian)" title="Peter James (historian)">Peter James</a>.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=6" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Chronology_of_the_ancient_Near_East" title="Chronology of the ancient Near East">Chronology of the ancient Near East</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=7" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">The date slowly varies within the <a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian calendar</a>, moving about three days later every four centuries. It presently occurs around the beginning of August.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=8" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626" /><div class="reflist reflist-columns references-column-width" style="column-width: 25em;"> <ol class="references"> <li id="cite_note-lavia-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-lavia_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-lavia_1-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation cs2"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131225071503/https://www.lavia.org/english/archivo/egyptiancalendaren.html">"Ancient Egyptian Civil Calendar"</a>, <a rel="nofollow" class="external text" href="http://www.lavia.org/indexIT.html"><i>La Via</i></a><span class="reference-accessdate">, retrieved <span class="nowrap">8 February</span> 2017</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Ancient+Egyptian+Civil+Calendar&rft.btitle=La+Via&rft_id=https%3A%2F%2Fweb.archive.org%2Fweb%2F20131225071503%2Fhttps%3A%2F%2Fwww.lavia.org%2Fenglish%2Farchivo%2Fegyptiancalendaren.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span>.</span> </li> <li id="cite_note-teacosy-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-teacosy_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-teacosy_3-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFTetley2014">Tetley (2014)</a>, p. <a rel="nofollow" class="external text" href="http://www.egyptchronology.com/uploads/2/6/9/4/26943741/ch_3_investigating_ancient_egyptian_calendars.pdf">42</a>.</span> </li> <li id="cite_note-Kitchen-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Kitchen_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Kitchen_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Kitchen_4-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Kitchen_4-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Kitchen_4-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFKitchen1991" class="citation journal cs1">Kitchen, K.A. (October 1991). "The chronology of Ancient Egypt". <i>World Archaeology</i>. <b>23</b> (2): 205. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F00438243.1991.9980172">10.1080/00438243.1991.9980172</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=World+Archaeology&rft.atitle=The+chronology+of+Ancient+Egypt&rft.volume=23&rft.issue=2&rft.pages=205&rft.date=1991-10&rft_id=info%3Adoi%2F10.1080%2F00438243.1991.9980172&rft.aulast=Kitchen&rft.aufirst=K.A.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-teatime-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-teatime_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-teatime_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFTetley2014" class="citation book cs1">Tetley, M. Christine (2014). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170211075421/http://www.egyptchronology.com/vols-1--2.html"><i>The Reconstructed Chronology of the Egyptian Kings</i></a>. Vol. I. p. <a rel="nofollow" class="external text" href="http://www.egyptchronology.com/uploads/2/6/9/4/26943741/ch_3_investigating_ancient_egyptian_calendars.pdf">43</a>. Archived from <a rel="nofollow" class="external text" href="http://www.egyptchronology.com/vols-1--2.html">the original</a> on 2017-02-11.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Reconstructed+Chronology+of+the+Egyptian+Kings&rft.pages=43&rft.date=2014&rft.aulast=Tetley&rft.aufirst=M.+Christine&rft_id=http%3A%2F%2Fwww.egyptchronology.com%2Fvols-1--2.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-Meyer-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-Meyer_6-0">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://archive.org/details/aegyptischechron00meye/page/41/mode/1up?view=theater">Meyer, Eduard, <i>Aegyptische Chronologie</i>, Berlin, Verlag der Königliche Akadamie der Wissenschaften (1904), Ch. I, p.41</a></span> </li> <li id="cite_note-Breasted-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-Breasted_7-0">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://archive.org/details/historyoftheanci034958mbp/page/15/mode/1up?view=theater">Breasted, James Henry, <i>A History of the Ancient Egyptians</i>, New York, Charles Scribner's Sons (1908), Ch. II, p.15</a> ("[T]he calendar year of 365 days was introduced in 4241 B.C., the earliest fixed date in the history of the world as known to us."), citing Meyer.</span> </li> <li id="cite_note-Grimal-1988-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-Grimal-1988_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Grimal-1988_8-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Grimal-1988_8-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Grimal-1988_8-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFGrimal1988" class="citation book cs1">Grimal, Nicolas (1988). <i>A History of Ancient Egypt</i>. Librairie Arthéme Fayard.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+History+of+Ancient+Egypt&rft.pub=Librairie+Arth%C3%A9me+Fayard&rft.date=1988&rft.aulast=Grimal&rft.aufirst=Nicolas&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFGautschyHabichtGalassiRutica2017" class="citation journal cs1">Gautschy, Rita; Habicht, Michael E.; Galassi, Francesco M.; Rutica, Daniela; Rühli, Frank J.; Hannig, Rainer (17 Nov 2017). <a rel="nofollow" class="external text" href="https://brill.com/view/journals/jeh/10/2/article-p69_69.xml">"A new astronomically-based chronological model for the Egyptian Old Kingdom"</a>. <i>Journal of Egyptian History</i>. <b>10</b> (2): <span class="nowrap">69–</span>108. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1163%2F18741665-12340035">10.1163/18741665-12340035</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1874-1657">1874-1657</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2021-01-24</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Egyptian+History&rft.atitle=A+new+astronomically-based+chronological+model+for+the+Egyptian+Old+Kingdom&rft.volume=10&rft.issue=2&rft.pages=%3Cspan+class%3D%22nowrap%22%3E69-%3C%2Fspan%3E108&rft.date=2017-11-17&rft_id=info%3Adoi%2F10.1163%2F18741665-12340035&rft.issn=1874-1657&rft.aulast=Gautschy&rft.aufirst=Rita&rft.au=Habicht%2C+Michael+E.&rft.au=Galassi%2C+Francesco+M.&rft.au=Rutica%2C+Daniela&rft.au=R%C3%BChli%2C+Frank+J.&rft.au=Hannig%2C+Rainer&rft_id=https%3A%2F%2Fbrill.com%2Fview%2Fjournals%2Fjeh%2F10%2F2%2Farticle-p69_69.xml&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFIngham1969" class="citation journal cs1">Ingham, M.F. (1969). "The length of the Sothic cycle". <i>The Journal of Egyptian Archaeology</i>. <b>55</b>: <span class="nowrap">36–</span>40. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1177%2F030751336905500105">10.1177/030751336905500105</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:192288579">192288579</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Journal+of+Egyptian+Archaeology&rft.atitle=The+length+of+the+Sothic+cycle&rft.volume=55&rft.pages=%3Cspan+class%3D%22nowrap%22%3E36-%3C%2Fspan%3E40&rft.date=1969&rft_id=info%3Adoi%2F10.1177%2F030751336905500105&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A192288579%23id-name%3DS2CID&rft.aulast=Ingham&rft.aufirst=M.F.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text">SkyCharts III<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citing_sources#What_information_to_include" title="Wikipedia:Citing sources"><span title="A complete citation is needed. (January 2021)">full citation needed</span></a></i>]</sup></span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFBuchwald2003" class="citation magazine cs1"><a href="/wiki/Jed_Buchwald" title="Jed Buchwald">Buchwald, Jed Z.</a> (2003). <a rel="nofollow" class="external text" href="http://calteches.library.caltech.edu/4096/1/Egyptian.pdf">"Egyptian stars under Paris skies"</a> <span class="cs1-format">(PDF)</span>. <i>Engineering and Science</i>. Caltech. Vol. 66, no. 4. Pasadena, CA: California Institute of Technology. pp. <span class="nowrap">20–</span>31.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Engineering+and+Science&rft.atitle=Egyptian+stars+under+Paris+skies&rft.volume=66&rft.issue=4&rft.pages=%3Cspan+class%3D%22nowrap%22%3E20-%3C%2Fspan%3E31&rft.date=2003&rft.aulast=Buchwald&rft.aufirst=Jed+Z.&rft_id=http%3A%2F%2Fcalteches.library.caltech.edu%2F4096%2F1%2FEgyptian.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text">One day per 120 years, see <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFWinlock1940" class="citation journal cs1">Winlock, H. (1940). "Origin of the Ancient Egyptian calendar". <i>Proceedings of the American Philosophical Society</i>. <b>83</b>: <span class="nowrap">447–</span>464.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+American+Philosophical+Society&rft.atitle=Origin+of+the+Ancient+Egyptian+calendar&rft.volume=83&rft.pages=%3Cspan+class%3D%22nowrap%22%3E447-%3C%2Fspan%3E464&rft.date=1940&rft.aulast=Winlock&rft.aufirst=H.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-vdMieroop-2015-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-vdMieroop-2015_14-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFvan_de_Mieroop2015" class="citation book cs1"><a href="/wiki/Marc_Van_de_Mieroop" class="mw-redirect" title="Marc Van de Mieroop">van de Mieroop, Marc</a> (2015). <i>A History of the Ancient Near East, ca. 3000–323 BC</i>. Oxford, UK: Wiley-Blackwell. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1118718162" title="Special:BookSources/978-1118718162"><bdi>978-1118718162</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+History+of+the+Ancient+Near+East%2C+ca.+3000%E2%80%93323+BC&rft.place=Oxford%2C+UK&rft.pub=Wiley-Blackwell&rft.date=2015&rft.isbn=978-1118718162&rft.aulast=van+de+Mieroop&rft.aufirst=Marc&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFRitnerMoeller2014" class="citation journal cs1">Ritner, Robert K.; Moeller, Nadine (2014). "The Ahmose 'Tempest Stela', Thera, and comparative chronology". <i>Journal of Near Eastern Studies</i>. <b>73</b> (1): <span class="nowrap">1–</span>19. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1086%2F675069">10.1086/675069</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/10.1086/675069">10.1086/675069</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:161410518">161410518</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Near+Eastern+Studies&rft.atitle=The+Ahmose+%27Tempest+Stela%27%2C+Thera%2C+and+comparative+chronology&rft.volume=73&rft.issue=1&rft.pages=%3Cspan+class%3D%22nowrap%22%3E1-%3C%2Fspan%3E19&rft.date=2014&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A161410518%23id-name%3DS2CID&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F10.1086%2F675069%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.1086%2F675069&rft.aulast=Ritner&rft.aufirst=Robert+K.&rft.au=Moeller%2C+Nadine&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFJames1991" class="citation book cs1"><a href="/wiki/Peter_James_(historian)" title="Peter James (historian)">James, Peter</a> (1991). <a rel="nofollow" class="external text" href="http://www.centuries.co.uk/index.htm"><i>Centuries of Darkness</i></a>. London, UK.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Centuries+of+Darkness&rft.place=London%2C+UK&rft.date=1991&rft.aulast=James&rft.aufirst=Peter&rft_id=http%3A%2F%2Fwww.centuries.co.uk%2Findex.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASothic+cycle" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_book" title="Template:Cite book">cite book</a>}}</code>: CS1 maint: location missing publisher (<a href="/wiki/Category:CS1_maint:_location_missing_publisher" title="Category:CS1 maint: location missing publisher">link</a>)</span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Sothic_cycle&action=edit&section=9" title="Edit section: External links"><span>edit</span></a><span 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topics</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Archaeology" title="Archaeology">Archaeology</a></li> <li><a href="/wiki/Astronomy" title="Astronomy">Astronomy</a></li> <li><a href="/wiki/Geology" title="Geology">Geology</a></li> <li><a href="/wiki/History" title="History">History</a> <ul><li><a href="/wiki/Big_History" title="Big History">Big History</a></li></ul></li> <li><a href="/wiki/Paleontology" title="Paleontology">Paleontology</a></li> <li><a href="/wiki/Time" title="Time">Time</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><div class="hlist"><ul><li><a href="/wiki/Periodization" title="Periodization">Periods</a></li><li><a href="/wiki/Era" title="Era">Eras</a></li><li><a href="/wiki/Epoch_(reference_date)" class="mw-redirect" title="Epoch (reference date)">Epochs</a></li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Calendar_era" title="Calendar era">Calendar eras</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Human Era</a></li> <li><i><a href="/wiki/Ab_urbe_condita" title="Ab urbe condita">Ab urbe condita</a></i></li> <li><a href="/wiki/Anno_Domini" title="Anno Domini">Anno Domini</a> / <a href="/wiki/Common_Era" title="Common Era">Common Era</a></li> <li><a href="/wiki/Anno_Mundi" title="Anno Mundi">Anno Mundi</a></li> <li><a href="/wiki/Bosporan_era" title="Bosporan era">Bosporan era</a></li> <li><a href="/wiki/Bostran_era" title="Bostran era">Bostran era</a></li> <li><a href="/wiki/Byzantine_calendar" title="Byzantine calendar">Byzantine era</a></li> <li><a href="/wiki/Seleucid_era" title="Seleucid era">Seleucid era</a></li> <li><a href="/wiki/Era_of_Caesar_(Iberian_Peninsula)" class="mw-redirect" title="Era of Caesar (Iberian Peninsula)">Era of Caesar (Iberia)</a></li> <li><a href="/wiki/Before_present" class="mw-redirect" title="Before present">Before present</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Hijri</a></li> <li><a href="/wiki/Egyptian_chronology" title="Egyptian chronology">Egyptian</a></li> <li><a class="mw-selflink selflink">Sothic cycle</a></li> <li><a href="/wiki/Hindu_units_of_time" title="Hindu units of time">Hindu units of time</a> (<a href="/wiki/Yuga" title="Yuga">Yuga</a>)</li> <li><a href="/wiki/Mesoamerican_calendars" title="Mesoamerican calendars">Mesoamerican</a> <ul><li><a href="/wiki/Mesoamerican_Long_Count_calendar" title="Mesoamerican Long Count calendar">Long Count</a></li> <li><a href="/wiki/Maya_calendar#Short_Count" title="Maya calendar">Short Count</a></li> <li><a href="/wiki/Tzolk%27in" class="mw-redirect" title="Tzolk'in">Tzolk'in</a></li> <li><a href="/wiki/Haab%27" class="mw-redirect" title="Haab'">Haab'</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Regnal_year" title="Regnal year">Regnal year</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Anka_year" title="Anka year">Anka year</a></li> <li><a href="/wiki/Canon_of_Kings" title="Canon of Kings">Canon of Kings</a></li> <li><a href="/wiki/Regnal_years_of_English_and_British_monarchs" title="Regnal years of English and British monarchs">English and British regnal year</a></li> <li><a href="/wiki/Category:Regnal_lists" title="Category:Regnal lists">Lists of kings</a></li> <li><a href="/wiki/Limmu" title="Limmu">Limmu</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Regnal_year" title="Regnal year">Era names</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chinese_era_name" title="Chinese era name">Chinese</a></li> <li><a href="/wiki/Japanese_era_name" title="Japanese era name">Japanese</a></li> <li><a href="/wiki/Korean_era_name" title="Korean era name">Korean</a></li> <li><a href="/wiki/Vietnamese_era_name" title="Vietnamese era name">Vietnamese</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Calendar" title="Calendar">Calendars</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Pre-Julian / Julian</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Roman_calendar" title="Roman calendar">Pre-Julian Roman</a></li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Original Julian</a></li> <li><a href="/wiki/Proleptic_Julian_calendar" title="Proleptic Julian calendar">Proleptic Julian</a></li> <li><a href="/wiki/Revised_Julian_calendar" title="Revised Julian calendar">Revised Julian</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Gregorian</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Proleptic_Gregorian_calendar" title="Proleptic Gregorian calendar">Proleptic Gregorian</a></li> <li><a href="/wiki/Old_Style_and_New_Style_dates" title="Old Style and New Style dates">Old Style and New Style dates</a></li> <li><a href="/wiki/Adoption_of_the_Gregorian_calendar" title="Adoption of the Gregorian calendar">Adoption of the Gregorian calendar</a></li> <li><a href="/wiki/Dual_dating" title="Dual dating">Dual dating</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Astronomical</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a> (<a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a>, <a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a>)</li> <li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a> (<a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a>)</li> <li><a href="/wiki/Astronomical_year_numbering" title="Astronomical year numbering">Astronomical year numbering</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Others</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Sexagenary_cycle" title="Sexagenary cycle">Chinese sexagenary cycle</a></li> <li><a href="/wiki/Geologic_Calendar" title="Geologic Calendar">Geologic Calendar</a></li> <li><a href="/wiki/Iranian_calendars" title="Iranian calendars">Iranian</a></li> <li><a href="/wiki/ISO_week_date" title="ISO week date">ISO week date</a></li> <li><a href="/wiki/Mesoamerican_calendars" title="Mesoamerican calendars">Mesoamerican</a> <ul><li><a href="/wiki/Maya_calendar" title="Maya calendar">Maya</a></li> <li><a href="/wiki/Aztec_calendar" title="Aztec calendar">Aztec</a></li></ul></li> <li><a href="/wiki/Winter_count" title="Winter count">Winter count</a></li> <li><a href="/wiki/New_Earth_Time" title="New Earth Time">New Earth Time</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomic time</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;background:#fff;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cosmic_Calendar" title="Cosmic Calendar">Cosmic Calendar</a></li> <li><a href="/wiki/Ephemeris" title="Ephemeris">Ephemeris</a></li> <li><a href="/wiki/Galactic_year" title="Galactic year">Galactic year</a></li> <li><a href="/wiki/Metonic_cycle" title="Metonic cycle">Metonic cycle</a></li> <li><a href="/wiki/Milankovitch_cycles" title="Milankovitch cycles">Milankovitch cycles</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geologic time</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Concepts</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Deep_time" title="Deep time">Deep time</a></li> <li><a href="/wiki/Geological_history_of_Earth" title="Geological history of Earth">Geological history of Earth</a></li> <li><a href="/wiki/Geologic_time_scale#Terminology" title="Geologic time scale">Geological time units</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Standards</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Global_Standard_Stratigraphic_Age" title="Global Standard Stratigraphic Age">Global Standard Stratigraphic Age (GSSA)</a></li> <li><a href="/wiki/Global_Boundary_Stratotype_Section_and_Point" title="Global Boundary Stratotype Section and Point">Global Boundary Stratotype Section and Point (GSSP)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Methods</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronostratigraphy" title="Chronostratigraphy">Chronostratigraphy</a></li> <li><a href="/wiki/Geochronology" title="Geochronology">Geochronology</a></li> <li><a href="/wiki/Isotope_geochemistry" title="Isotope geochemistry">Isotope geochemistry</a></li> <li><a href="/wiki/Law_of_superposition" title="Law of superposition">Law of superposition</a></li> <li><a href="/wiki/Luminescence_dating" title="Luminescence dating">Luminescence dating</a></li> <li><a href="/wiki/Samarium%E2%80%93neodymium_dating" title="Samarium–neodymium dating">Samarium–neodymium dating</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological<br />dating</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Absolute_dating" title="Absolute dating">Absolute dating</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Amino_acid_dating" title="Amino acid dating">Amino acid racemisation</a></li> <li><a href="/wiki/Archaeomagnetic_dating" title="Archaeomagnetic dating">Archaeomagnetic dating</a></li> <li><a href="/wiki/Dendrochronology" title="Dendrochronology">Dendrochronology</a></li> <li><a href="/wiki/Ice_core" title="Ice core">Ice core</a></li> <li><a href="/wiki/Incremental_dating" title="Incremental dating">Incremental dating</a></li> <li><a href="/wiki/Lichenometry" title="Lichenometry">Lichenometry</a></li> <li><a href="/wiki/Paleomagnetism" title="Paleomagnetism">Paleomagnetism</a></li> <li><a href="/wiki/Radiometric_dating" title="Radiometric dating">Radiometric dating</a> <ul><li><a href="/wiki/Lead%E2%80%93lead_dating" title="Lead–lead dating">Lead–lead</a></li> <li><a href="/wiki/K%E2%80%93Ar_dating" title="K–Ar dating">Potassium–argon</a></li> <li><a href="/wiki/Radiocarbon_dating" title="Radiocarbon dating">Radiocarbon</a></li> <li><a href="/wiki/Uranium%E2%80%93lead_dating" title="Uranium–lead dating">Uranium–lead</a></li></ul></li> <li><a href="/wiki/Tephrochronology" title="Tephrochronology">Tephrochronology</a></li> <li><a href="/wiki/Luminescence_dating" title="Luminescence dating">Luminescence dating</a></li> <li><a href="/wiki/Thermoluminescence_dating" title="Thermoluminescence dating">Thermoluminescence dating</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Relative_dating" title="Relative dating">Relative dating</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fluorine_absorption_dating" title="Fluorine absorption dating">Fluorine absorption</a></li> <li><a href="/wiki/Nitrogen_dating" title="Nitrogen dating">Nitrogen dating</a></li> <li><a href="/wiki/Obsidian_hydration_dating" title="Obsidian hydration dating">Obsidian hydration</a></li> <li><a href="/wiki/Seriation_(archaeology)" title="Seriation (archaeology)">Seriation</a></li> <li><a href="/wiki/Stratigraphy_(archaeology)" title="Stratigraphy (archaeology)">Stratigraphy</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;">Genetic methods</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Molecular_clock" title="Molecular clock">Molecular clock</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;">Linguistic methods</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Glottochronology" title="Glottochronology">Glottochronology</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;">Related topics</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronicle" title="Chronicle">Chronicle</a></li> <li><a href="/wiki/New_Chronology_(Fomenko)" class="mw-redirect" title="New Chronology (Fomenko)">New Chronology</a></li> <li><a href="/wiki/Synchronoptic_view" title="Synchronoptic view">Synchronoptic view</a></li> <li><a href="/wiki/Timeline" title="Timeline">Timeline</a></li> <li><a href="/wiki/Year_zero" title="Year zero">Year zero</a></li> <li><a href="/wiki/Floruit" title="Floruit">Floruit</a></li> <li><a href="/wiki/Terminus_post_quem" title="Terminus post quem">Terminus post quem</a></li> <li><a href="/wiki/ASPRO_chronology" title="ASPRO chronology">ASPRO chronology</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Sothic_cycle&oldid=1266555182">https://en.wikipedia.org/w/index.php?title=Sothic_cycle&oldid=1266555182</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Egyptian_calendar" title="Category:Egyptian calendar">Egyptian calendar</a></li><li><a href="/wiki/Category:Chronology" title="Category:Chronology">Chronology</a></li><li><a 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