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<p>[QUOTE=&quot;galapac, post: 2132646, member: 73406&quot;]Ok we are going to beat a dead horse...</p><p>From Wikipedia....</p><p><br /></p><p><b>Common Era</b> (<b>CE</b>) is the <a href="http://simple.wikipedia.org/wiki/Calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://simple.wikipedia.org/wiki/Calendar" rel="nofollow">calendar</a> system <a href="http://simple.wiktionary.org/wiki/common" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://simple.wiktionary.org/wiki/common" rel="nofollow">commonly</a> used in the <a href="http://simple.wikipedia.org/wiki/Western_world" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://simple.wikipedia.org/wiki/Western_world" rel="nofollow">Western world</a> for the <a href="http://simple.wikipedia.org/wiki/Year" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://simple.wikipedia.org/wiki/Year" rel="nofollow">year</a> number part of a <a href="http://simple.wikipedia.org/wiki/Date" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://simple.wikipedia.org/wiki/Date" rel="nofollow">date</a>. The year numbers are the same as those used for <i><a href="http://simple.wikipedia.org/wiki/Anno_Domini" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://simple.wikipedia.org/wiki/Anno_Domini" rel="nofollow">Anno Domini</a></i> (AD); in both systems the current year is 2015. The CE and AD systems both started with the year 1.<b> Neither system uses a year zero (0).</b> Common Era is abbreviated as <b>CE</b>, and is also known as <b>Current Era</b> and <b>Christian Era</b>.</p><p><br /></p><p><a href="http://en.wikipedia.org/wiki/Common_Era" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Common_Era" rel="nofollow">http://en.wikipedia.org/wiki/Common_Era</a></p><p><br /></p><p><b>Year zero</b> does not exist in the <a href="http://en.wikipedia.org/wiki/Anno_Domini" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Anno_Domini" rel="nofollow">Anno Domini</a> (or <a href="http://en.wikipedia.org/wiki/Common_Era" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Common_Era" rel="nofollow">Common Era</a>) system usually used to number years in the <a href="http://en.wikipedia.org/wiki/Gregorian_calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Gregorian_calendar" rel="nofollow">Gregorian calendar</a> and in its predecessor, the <a href="http://en.wikipedia.org/wiki/Julian_calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Julian_calendar" rel="nofollow">Julian calendar</a>. In this system, the year <a href="http://en.wikipedia.org/wiki/1_BC" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/1_BC" rel="nofollow">1 BC</a> is followed by <a href="http://en.wikipedia.org/wiki/1" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/1" rel="nofollow">AD 1</a>. However, there is a year zero in <a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering" rel="nofollow">astronomical year numbering</a> (where it coincides with the Julian year 1 BC) and in <a href="http://en.wikipedia.org/wiki/ISO_8601" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/ISO_8601" rel="nofollow">ISO 8601:2004</a> (where it coincides with the Gregorian year 1 BC) as well as in all <a href="http://en.wikipedia.org/wiki/Buddhist_calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Buddhist_calendar" rel="nofollow">Buddhist</a> and <a href="http://en.wikipedia.org/wiki/Hindu_calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Hindu_calendar" rel="nofollow">Hindu calendars</a>.</p><p><br /></p><p><a href="http://en.wikipedia.org/wiki/0_(year" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/0_(year" rel="nofollow">http://en.wikipedia.org/wiki/0_(year</a>)</p><p><br /></p><p><b>Astronomical year numbering</b> is based on <a href="http://en.wikipedia.org/wiki/Anno_Domini" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Anno_Domini" rel="nofollow">AD</a>/<a href="http://en.wikipedia.org/wiki/Common_Era" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Common_Era" rel="nofollow">CE</a> year numbering, but follows normal <a href="http://en.wikipedia.org/wiki/Decimal" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Decimal" rel="nofollow">decimal</a> <a href="http://en.wikipedia.org/wiki/Integer" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Integer" rel="nofollow">integer</a> numbering more strictly. Thus, it has a <a href="http://en.wikipedia.org/wiki/0_(year)" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/0_(year)" rel="nofollow">year 0</a>, the years before that are designated with <a href="http://en.wikipedia.org/wiki/Negative_number" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Negative_number" rel="nofollow">negative numbers</a> and the years after that are designated with positive numbers.<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" rel="nofollow">[1]</a> Astronomers use the <a href="http://en.wikipedia.org/wiki/Julian_calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Julian_calendar" rel="nofollow">Julian calendar</a> for years before 1582, including this year 0, and the <a href="http://en.wikipedia.org/wiki/Gregorian_calendar" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Gregorian_calendar" rel="nofollow">Gregorian calendar</a> for years after 1582 as exemplified by <a href="http://en.wikipedia.org/wiki/Jacques_Cassini" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Jacques_Cassini" rel="nofollow">Jacques Cassini</a> (1740),<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-Cassini-2" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-Cassini-2" rel="nofollow">[2]</a> <a href="http://en.wikipedia.org/wiki/Simon_Newcomb" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Simon_Newcomb" rel="nofollow">Simon Newcomb</a> (1898)<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-3" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-3" rel="nofollow">[3]</a> and <a href="http://en.wikipedia.org/wiki/Fred_Espenak" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Fred_Espenak" rel="nofollow">Fred Espenak</a> (2007).<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-Espanak-4" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-Espanak-4" rel="nofollow">[4]</a></p><p>The prefix AD and the suffixes CE, BC or BCE (Common Era, Before Christ or Before Common Era) are dropped.<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" rel="nofollow">[1]</a> The year 1 BC/BCE is numbered 0, the year 2 BC is numbered −1, and in general the year <i>n</i> BC/BCE is numbered &quot;−(<i>n</i> − 1)&quot;<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" rel="nofollow">[1]</a> (a negative number equal to 1 − <i>n</i>). The numbers of AD/CE years are not changed and are written with either no sign or a positive sign; thus in general <i>n</i> AD/CE is simply <i>n</i> or +<i>n</i>.<a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering#cite_note-nasa-eclipses-1" rel="nofollow">[1]</a> For normal calculation a <a href="http://en.wikipedia.org/wiki/0_(number)" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/0_(number)" rel="nofollow">number zero</a> is often needed, here most notably when calculating the number of years in a period that spans the <a href="http://en.wikipedia.org/wiki/Epoch_(astronomy)" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Epoch_(astronomy)" rel="nofollow">epoch</a>; the end years need only be subtracted from each other.</p><p>The system is so named due to its use in <a href="http://en.wikipedia.org/wiki/Astronomy" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomy" rel="nofollow">astronomy</a>. Few other disciplines outside <a href="http://en.wikipedia.org/wiki/History" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/History" rel="nofollow">history</a> deal with the time before year 1, some exceptions being <a href="http://en.wikipedia.org/wiki/Dendrochronology" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Dendrochronology" rel="nofollow">dendrochronology</a>, <a href="http://en.wikipedia.org/wiki/Archaeology" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Archaeology" rel="nofollow">archaeology</a> and <a href="http://en.wikipedia.org/wiki/Geology" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Geology" rel="nofollow">geology</a>, the latter two of which use &#039;<a href="http://en.wikipedia.org/wiki/Before_Present" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Before_Present" rel="nofollow">years before the present</a>&#039;. Although the absolute numerical values of astronomical and historical years only differ by one before year 1, this difference is critical when calculating astronomical events like <a href="http://en.wikipedia.org/wiki/Eclipses" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Eclipses" rel="nofollow">eclipses</a> or <a href="http://en.wikipedia.org/wiki/Planetary_conjunction" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Planetary_conjunction" rel="nofollow">planetary conjunctions</a> to determine when historical events which mention them occurred.</p><p><br /></p><p><a href="http://en.wikipedia.org/wiki/Astronomical_year_numbering" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Astronomical_year_numbering" rel="nofollow">http://en.wikipedia.org/wiki/Astronomical_year_numbering</a></p><p><br /></p><p><br /></p><p>So it would appear that&nbsp; the year &quot;0&quot; is used in Astronomical year numbering for its use in astronomy. Which calendar do you follow? I pretty much follow the world standard Gregorian Calendar...<img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie2" alt=";)" unselectable="on" unselectable="on" />[/QUOTE]</p><p><br /></p>

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