{ "export": { "source": "https://urth.darkrealm.vip/thread/urth/1740", "note": "Exported from an unofficial mirror of a public mailing list. Copyright in each message remains with the person who wrote it. Email addresses are obscured as `user at host`, the form the original archive published. This file was rebuilt from parsed fields rather than retained headers, so it is faithful in content but not byte-exact.", "addresses": "obscured as 'user at host'" }, "archive": "urth", "thread": { "id": 1740, "subject": "lunar calendars [Digest urth.v028.n014]", "messages": 3, "voices": 3, "first": "1999-08-12T14:52:29+00:00", "last": "1999-08-28T21:15:38+00:00" }, "messages": [ { "message_id": "", "from": { "name": "John Bishop", "address": "jbishop at blkbrd.zko.dec.com" }, "date": "1999-08-12T16:08:53+00:00", "subject": "(urth) Re: lunar calendars [Digest urth.v028.n014]", "in_reply_to": null, "reply_link": null, "blocks": [ { "kind": "text", "depth": 0, "text": "Mantis says:" }, { "kind": "quote", "depth": 1, "text": "Lunar calendars have thirteen months (13 x 28 = 364). Period." }, { "kind": "text", "depth": 0, "text": "Not that I ever read. The islamic calendar still offically\ndepends on a witness to the new Moon, the Judaic calendar used\nto (before it could rely on calculation), and the Classic \nworld's lunar calendars did also (in particular, the calendars\nused to calculate possible eclipse times), though in later\ntimes astronomers calculated a sequence of short and long\nmonths that would be predictable (by reference) but never\nmore than half a day off the real new Moon.\n\nA fixed lunar calendar would pretty quickly cease to be aligned\nwith the moon, which kind of loses the point, and produces the\nkind of \"months\" we have, which are unrelated to the Moon.\n\nThus a year would be either 12 or 13 months, depending on whether\nit had an extra month or not (Judaic \"second Adar\"), and the \nmonths would have either 28 or 29 days. Trusted witnesses would\nlook at the sky, searching for a new Moon to start a new month,\nand a trusted (priestly) authority would determine when to insert\nan extra month depending on astronomical observations (such as\nthe Pontifex Maximus in Rome).\n\nDuring the late Classic time, there was a 19-year cycle of long\nand short months, long and short years which kept the Moon phase\npredicted by the calendar within half a day of the real Moon\nphase, and the seasons within half a month of the real season,\nso direct observation (and the consequent need for messengers to\nspread the news, etc.) wasn't required.\n\nIt wasn't perfect (there was a long-term drift), and there was a\n57-year cycle which solved most of the drift, but it never became\nwidely accepted. The 19-year calendar was useful because the\neclipse cycle is also 19 years (due to the precession of the\nmoon's orbit, which moves the location of the ascending and \ndescending nodes of the moon's orbit along the ecliptic). You\ncould put \"eclipse\" seasons into the 19-year cycle: they marked\nthe points at which the Earth, Moon and Sun were aligned in such\na way that an eclipse was very likely.\n\nSee Abell's astronomy text and various encyclopedias. I once long\nago programed up a calendar maker which used modern data to construct\nthe 19 and 57 year calendars, but I don't know if the Classic ones\nwould have had the same distribution of longs and shorts.\n\n -John Bishop" } ] }, { "message_id": "", "from": { "name": "Michael Andre-Driussi", "address": "mantis at sirius.com" }, "date": "1999-08-12T14:52:29+00:00", "subject": "Re: (urth) Re: lunar calendars [Digest urth.v028.n014]", "in_reply_to": "", "reply_link": "subject", "blocks": [ { "kind": "text", "depth": 0, "text": "John Bishop," }, { "kind": "quote", "depth": 1, "text": "Mantis says:" }, { "kind": "quote", "depth": 2, "text": "Lunar calendars have thirteen months (13 x 28 = 364). Period." }, { "kind": "quote", "depth": 1, "text": "Not that I ever read. The islamic calendar still offically\ndepends on a witness to the new Moon, the Judaic calendar used\nto (before it could rely on calculation), and the Classic\nworld's lunar calendars did also (in particular, the calendars\nused to calculate possible eclipse times), though in later\ntimes astronomers calculated a sequence of short and long\nmonths that would be predictable (by reference) but never\nmore than half a day off the real new Moon.\n\nA fixed lunar calendar would pretty quickly cease to be aligned\nwith the moon, which kind of loses the point, and produces the\nkind of \"months\" we have, which are unrelated to the Moon." }, { "kind": "text", "depth": 0, "text": "Maybe there is trouble caused by the term \"calendar\"? That is, if I wrote\n\"Lunar reckoning\" rather than \"Lunar calendar,\" would that clear up some of\nthe problems? (\"Calendar\" carries such imperial trappings, such a sense of\nprecision, or something written down, at least.) Because by the \"Lunar\nreckoning\" I'm describing, the situation can =never= cease to be aligned\nwith the Moon; by the same token, dates are about as fluid as the watches\nof the day (where they have no mechanical timepieces, nor do they even\nassign sequential numbers to the watches). And years are numbered by the\nreign of the Autarch.\n\nI am aware of the \"Lunar\" calendars you mention, and frankly I think they\nget into the trouble they do because they are trying to match the solar\nyear (and see next paragraph). I sense that they are hybrid Lunar\ncalendars, born from a tradition of simple Lunar reckoning and then\nretrofitted to approximate a solar calendar. (I also believe that the\nnumber of thirteen months to Lunar reckoning is the largest contributor to\nthe taboo/\"unlucky\" nature of the number 13--shows how deep these arguments\nrun!)\n\nI'm also aware that those pesky fractions (29.nnn days per lunar month)\nwill throw the counting off--after all, that was the impetus to have\nalternating long and short months (I've seen Chinese women calculate long\nand short months of their Lunar calendar by somehow counting on the\nknuckles of their fists--don't ask me how). Then again, what with the\nterraforming and all, the 1.nnn fraction may have been shaved off! (And 28\nis handy because it divides evenly by seven, and . . . uh oh, next we'll be\narguing on how many weeks there are to a year!)\n\nIn addition to historical examples I've also seen models for interesting\nmodern solar calendars (aside from that of the French Republic) that will\nfix one problem or another. One, for example, that has thirteen months\n(the new one being \"SOL,\" inserted between JUN and JUL) of exactly 28 days\neach (13 x 28 = 364), where the 13th of every month is always a Friday, and\na special off-calendar day for New Year's Day (364 + 1 = 365), plus a bonus\noff-calendar day every fourth year. Whooh!\n\n(Kind of like the \"missing time\" in the Martian day of Kim Stanley\nRobinson's RED MARS--have a quick party, we're outside of time!)\n\nNow then, I think the point of all this is =not= that Wolfe worked out any\nsort of Lunar reckoning and/or calendar. The point is (or so it seems to\nme) that in the Commonwealth they are crushed by history; time to them does\nnot have the precise, mechanistic sense that it does to us--theirs is\n\"medieval\" or even more primitive, yet it suits them fine. The zinger\nbeing that they are the heirs of a starfaring culture, yet they have sunk\nto this level, a deeper, longer dark age, such that they do not have a\ncalendar (also implying a loss of astronomical skills) . . . the Aztecs\nwere basically neolithic, but they had a very elaborate calendar (to say\nnothing of Mesopotamia). So the Commonwealth would appear to be less\ndeveloped than a neolithic level in this regard.\n\nPlus, hinting at different calendars/time reckoning systems, etc., is a\nneat way to imply \"otherness,\" to give the sense of strange-yet-valid (if\nnot very accurate). One of the details I look for in sf.\n\nAnd time proves to be even more fluid and fuzzy, as the story progresses.\n\n=mantis=" } ] }, { "message_id": "", "from": { "name": "Derek Bell", "address": "dbell at maths.tcd.ie" }, "date": "1999-08-28T21:15:38+00:00", "subject": "Re: (urth) Re: lunar calendars [Digest urth.v028.n014]", "in_reply_to": "", "reply_link": "subject", "blocks": [ { "kind": "text", "depth": 0, "text": "In message <199908122009.NAA08988 at lists1.best.com>, John Bishop writes:" }, { "kind": "quote", "depth": 1, "text": "Mantis says:" }, { "kind": "quote", "depth": 2, "text": "Lunar calendars have thirteen months (13 x 28 = 364). Period." }, { "kind": "quote", "depth": 1, "text": "Not that I ever read. The islamic calendar still offically\ndepends on a witness to the new Moon, the Judaic calendar used\nto (before it could rely on calculation), and the Classic \nworld's lunar calendars did also (in particular, the calendars\nused to calculate possible eclipse times), though in later\ntimes astronomers calculated a sequence of short and long\nmonths that would be predictable (by reference) but never\nmore than half a day off the real new Moon." }, { "kind": "text", "depth": 0, "text": " The Islamic calendar is also exclusively *lunar* based with a\nmean year shorter than the solar year. I once did a\nback-of-the-envelope calculation about when the two calendars would\nhave the same year simultaneously - sometime after the 30th century,\nIIRC. " }, { "kind": "quote", "depth": 1, "text": "See Abell's astronomy text and various encyclopedias. I once long\nago programed up a calendar maker which used modern data to construct\nthe 19 and 57 year calendars, but I don't know if the Classic ones\nwould have had the same distribution of longs and shorts." }, { "kind": "text", "depth": 0, "text": " I'd also suggest _Calendrical Calculations_ by Dershowitz and\nReingold - a web site with sample material is at\nhttp://emr.cs.uiuc.edu/home/reingold/calendar-book/index.shtml\n\n\tDerek Bell" } ] } ] }