{ "export": { "source": "https://urth.darkrealm.vip/thread/urth/3033", "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": 3033, "subject": "Green's diameter, angular and otherwise", "messages": 5, "voices": 3, "first": "2002-03-13T02:19:24+00:00", "last": "2002-03-14T22:27:38+00:00" }, "messages": [ { "message_id": "", "from": { "name": "Michael Andre-Driussi", "address": "mantis at siriusfiction.com" }, "date": "2002-03-13T02:19:24+00:00", "subject": "(urth) Green's diameter, angular and otherwise", "in_reply_to": null, "reply_link": null, "blocks": [ { "kind": "text", "depth": 0, "text": "Another way to approach the Blue/Green conjunction is to determine the size\nof Green in the sky of Blue, from its \"usual\" size to its greatest size at\nclosest approach.\n\nFor simplicity sake, let us assume that both Blue and Green have surface\ngravities of 1 g. More or less \"twins\" in separate orbits (and Green\nhaving an orbital eccentricity that carries it out to a close approach with\nBlue every x number of local years).\n\nI was watching for details when I read before and I don't recall finding\nany, other than \"baneful eye.\"\n\nOTOH, we have the happy case of an eyewitness who also sees Lune (maybe?)\nand the Old Sun (definitely). The Old Sun (assumed before to have an\nangular diamter of around 0.83 degrees) is \"swollen\" to his eyes, but iirc\nhe never says anything in comparison to Green's biggest size.\n\nUsing the Moon as a model.\n ORBIT ANGULAR DIAMETER\nMOON 240,000 0.52 degrees\nLUNE 150,000 0.83 degrees\nGREEN 105,000 1.18 degrees\n\nSo even a puny world like the Moon (diameter 2160 miles) would be more than\ntwice the size of the Moon in our sky when located at a distance attributed\nto Green.\n\nA twin planet would naturally be much bigger.\n\nBased upon this, the Bluvian astronomer is quite likely to be waaaay off in\nhis estimate of the \"closest approach\" distance as being 35,000 leagues.\n\n=mantis=\n\n\nSIRIUS FICTION\nbooklets on Gene Wolfe, John Crowley\n43 Lexicons left until OP!\nhttp://www.siriusfiction.com/" } ] }, { "message_id": "", "from": { "name": "Jerry Friedman", "address": "jerry_friedman at yahoo.com" }, "date": "2002-03-13T16:50:29+00:00", "subject": "Re: (urth) Green's diameter, angular and otherwise", "in_reply_to": "", "reply_link": "subject", "blocks": [ { "kind": "quote", "depth": 1, "text": "--- Michael Andre-Driussi wrote:\nAnother way to approach the Blue/Green conjunction is to determine the\nsize\nof Green in the sky of Blue, from its \"usual\" size to its greatest size\nat\nclosest approach.\n\nFor simplicity sake, let us assume that both Blue and Green have surface\ngravities of 1 g. More or less \"twins\" in separate orbits (and Green\nhaving an orbital eccentricity that carries it out to a close approach\nwith\nBlue every x number of local years)." }, { "kind": "text", "depth": 0, "text": "I don't think the eccentricity has much to do with it. The two\nplanets will come into conjunction every x number of local years. If\nGreen's orbit is eccentric, then sometimes the distance at conjunction\nwill be greater and sometimes less." }, { "kind": "quote", "depth": 1, "text": "I was watching for details when I read before and I don't recall finding\nany, other than \"baneful eye.\"\n\nOTOH, we have the happy case of an eyewitness who also sees Lune\n(maybe?)\nand the Old Sun (definitely). The Old Sun (assumed before to have an\nangular diamter of around 0.83 degrees) is \"swollen\" to his eyes, but\niirc\nhe never says anything in comparison to Green's biggest size.\n\nUsing the Moon as a model.\n ORBIT ANGULAR DIAMETER\nMOON 240,000 0.52 degrees\nLUNE 150,000 0.83 degrees\nGREEN 105,000 1.18 degrees\n\nSo even a puny world like the Moon (diameter 2160 miles) would be more\nthan\ntwice the size of the Moon in our sky when located at a distance\nattributed\nto Green.\n\nA twin planet would naturally be much bigger.\n\nBased upon this, the Bluvian astronomer is quite likely to be waaaay off\nin\nhis estimate of the \"closest approach\" distance as being 35,000 leagues." }, { "kind": "text", "depth": 0, "text": "How are you thinking the Bluvian astronomer would make his estimate?\nI can't think of a method that would be thrown off by Green's large\nsize. The only way I know of at the Green level of technology would be\nparallax, which doesn't depend on Green's angular size at all. (Though\nthe parallax method would require a fair amount of work, notably\nmeasuring the distances between widely separated cities, as well as\nastronomical observations at conjunction, which is presumably the\nworst possible time. Seems unlikely during the first twenty years\nof settlement.)\n\nMaybe Gagliardo used observations made from the lander and\ninformation from the monitors, who could at least have told him\nthe cruising speed of the landers. Or maybe he's doing the same\nthing we're doing and guessing that the Short Sun is the same size\nand brightness as the Old Sun, which makes the radius of Blue's\norbit the same as Urth's (if he knows it); then from the time\nbetween conjunctions he can get the radius of Green's orbit.\n\nAnyway, the higher the true distance, the harder the problem of how\nthe inhumi cross.\n\nJerry Friedman" } ] }, { "message_id": "", "from": { "name": "Dan'l Danehy-Oakes", "address": "ddanehy at siebel.com" }, "date": "2002-03-13T17:07:28+00:00", "subject": "RE: (urth) Green's diameter, angular and otherwise", "in_reply_to": "", "reply_link": "subject", "blocks": [ { "kind": "quote", "depth": 2, "text": "Mantis wrote:\nUsing the Moon as a model.\n ORBIT ANGULAR DIAMETER\nMOON 240,000 0.52 degrees\nLUNE 150,000 0.83 degrees\nGREEN 105,000 1.18 degrees\nSo even a puny world like the Moon (diameter 2160 miles) would be more\nthan twice the size of the Moon in our sky when located at a distance\nattributed to Green.\n\nA twin planet would naturally be much bigger.\n\nBased upon this, the Bluvian astronomer is quite likely to be waaaay off\nin his estimate of the \"closest approach\" distance as being 35,000\nleagues." }, { "kind": "text", "depth": 0, "text": "... for which I am frankly grateful, because it seems to me to drive the\nfinal nail into the \"Blue = Urth\" theory's coffin, based on past discussions\nherein.\n\nThen Jerry F. asks:" }, { "kind": "quote", "depth": 1, "text": "How are you thinking the Bluvian astronomer would make his estimate?\nI can't think of a method that would be thrown off by Green's large\nsize. " }, { "kind": "text", "depth": 0, "text": "I don't believe Mantis is referring to the Bluvian astronomer's \"method\"\nbut simply to his result. \n\nAt one level, Mantis refers to the description of Green, seen from Blue, \nas a \"baleful eye.\" A twin planet, or even the moon, seen at the distance \nof 105K miles, would be rather too large for an \"eye\" to be, at any rate, \nthe most obvious metaphor. \n\nMore important: from present evidence, it appears that Green, Blue, and \nUrth have fairly similar surface gravity (the evidence is, admittedly, \nnegative: there is no mention of a sensation of weighing more or less, \nno sense that thrown or swung objects behave differently, etc., and it\nis reasonable to suspect that _something_ of the sort would be mentioned) \n-- indeed, all these seem to be fairly close to the accelerational \n\"gravity\" of the Whorl at \"ground\" level. \n\n(BTW, the whole issue of the Fliers in a separate thread seems to miss \nthe point that they rarely - never voluntarily? - come near \"ground\" \nlevel.) \n\nThis being the case, Green needs to be at least somewhat similar in \nmass to Urth. Such a mass passing within 105K miles of Blue would have \neffects not terribly dissimilar to the effect of the passing of the \nWhite Fountain on Urth. (And, of course, vice versa for Green.) The \neffects described for the conjunction do not come close: for example, \nthe Narrator mentions extreme tides, but apparently they are not so \nextreme as to swamp a seaside town (New Viron) or to make a home near \nthe shore of an oceanic island (Horn's hut) infeasible over a period\nof decades." }, { "kind": "quote", "depth": 1, "text": "Anyway, the higher the true distance, the harder the problem of how\nthe inhumi cross." }, { "kind": "text", "depth": 0, "text": "True, but in any event the problem of how the inhumi cross between\nBleen and Grue is trivial next to the problem of how Remora (and,\napparently, other inhumi) achieved the crossing to the Whorl. If I\nrecall correctly, a Neighbor mentions to Horn that they (the Neighbors)\nsent them (the inhumi) - but does not describe how this was done. " } ] }, { "message_id": "", "from": { "name": "Jerry Friedman", "address": "jerry_friedman at yahoo.com" }, "date": "2002-03-14T22:02:27+00:00", "subject": "RE: (urth) Green's diameter, angular and otherwise", "in_reply_to": "", "reply_link": "subject", "blocks": [ { "kind": "quote", "depth": 1, "text": "--- Dan'l Danehy-Oakes wrote:\nMantis wrote:" }, { "kind": "quote", "depth": 3, "text": "Using the Moon as a model.\n ORBIT ANGULAR DIAMETER\nMOON 240,000 0.52 degrees\nLUNE 150,000 0.83 degrees\nGREEN 105,000 1.18 degrees\nSo even a puny world like the Moon (diameter 2160 miles) would be\nmore\nthan twice the size of the Moon in our sky when located at a\ndistance\nattributed to Green.\n\nA twin planet would naturally be much bigger.\n\nBased upon this, the Bluvian astronomer is quite likely to be waaaay\noff\nin his estimate of the \"closest approach\" distance as being 35,000\nleagues." }, { "kind": "quote", "depth": 1, "text": "... for which I am frankly grateful, because it seems to me to drive the\nfinal nail into the \"Blue = Urth\" theory's coffin, based on past\ndiscussions\nherein." }, { "kind": "text", "depth": 0, "text": "Okay, how? I too would be relieved, but I don't see the connection." }, { "kind": "quote", "depth": 1, "text": "Then Jerry F. asks:" }, { "kind": "quote", "depth": 2, "text": "How are you thinking the Bluvian astronomer would make his estimate?\nI can't think of a method that would be thrown off by Green's large\nsize. " }, { "kind": "quote", "depth": 1, "text": "I don't believe Mantis is referring to the Bluvian astronomer's \"method\"\nbut simply to his result. " }, { "kind": "text", "depth": 0, "text": "Ah, got it." }, { "kind": "quote", "depth": 1, "text": "At one level, Mantis refers to the description of Green, seen from Blue,\n\nas a \"baleful eye.\" A twin planet, or even the moon, seen at the\ndistance \nof 105K miles, would be rather too large for an \"eye\" to be, at any\nrate, \nthe most obvious metaphor. " }, { "kind": "text", "depth": 0, "text": "Au contraire, mon frere. Sundogs (mock suns, parhelia) have a good\ndeal more than twice the angular diameter of the moon, and one person\nwho talked to me about seeing one compared it repeatedly to God's eye\nlooking at her, perhaps accusingly. Anyway, the 105K miles is the\nclosest approach; most of the time Green looks much smaller. (Or was\nthat \"baleful\" eye right at conjunction?)" }, { "kind": "quote", "depth": 1, "text": "More important: from present evidence, it appears that Green, Blue, and \nUrth have fairly similar surface gravity (the evidence is, admittedly, \nnegative: there is no mention of a sensation of weighing more or less, \nno sense that thrown or swung objects behave differently, etc., and it\nis reasonable to suspect that _something_ of the sort would be\nmentioned) \n-- indeed, all these seem to be fairly close to the accelerational \n\"gravity\" of the Whorl at \"ground\" level. " }, { "kind": "text", "depth": 0, "text": "I think Marc just presented, not for the first time, cogent reasons\nto think that Green's gravity is less than the Earth's. I argued\na couple of days ago that nonetheless Green's gravity should be much\ngreater than the moon's, more or less for the reason you mention. I\nagree with you and him that there's no trace of any difference between\nEarth's gravity, Urth's, Blue's, and the _Whorl's_ \"gravity\"." }, { "kind": "quote", "depth": 1, "text": "(BTW, the whole issue of the Fliers in a separate thread seems to miss \nthe point that they rarely - never voluntarily? - come near \"ground\" \nlevel.) " }, { "kind": "text", "depth": 0, "text": "But they're capable of flying near ground level, at least for a little\nwhile. See Sciathan's discussion of his capture, if I remember it\ncorrectly." }, { "kind": "quote", "depth": 1, "text": "This being the case, Green needs to be at least somewhat similar in \nmass to Urth. Such a mass passing within 105K miles of Blue would have \neffects not terribly dissimilar to the effect of the passing of the \nWhite Fountain on Urth. (And, of course, vice versa for Green.) The \neffects described for the conjunction do not come close: for example, \nthe Narrator mentions extreme tides, but apparently they are not so \nextreme as to swamp a seaside town (New Viron) or to make a home near \nthe shore of an oceanic island (Horn's hut) infeasible over a period\nof decades." }, { "kind": "quote", "depth": 2, "text": "Anyway, the higher the true distance, the harder the problem of how\nthe inhumi cross." }, { "kind": "quote", "depth": 1, "text": "True, but in any event the problem of how the inhumi cross between\nBleen and Grue" }, { "kind": "text", "depth": 0, "text": "(or Blee and Groon, for King Crimson fans)" }, { "kind": "quote", "depth": 1, "text": "is trivial next to the problem of how Remora (and,\napparently, other inhumi) achieved the crossing to the Whorl. If I\nrecall correctly, a Neighbor mentions to Horn that they (the Neighbors)\nsent them (the inhumi) - but does not describe how this was done. " }, { "kind": "text", "depth": 0, "text": "I don't see that. It's one of the problems the Blue=Ushas theory is\nsupposed to solve, and for those of us who don't believe that, there\nwas plenty of space travel before Typhon. The problem of how inhumi\ngot onto the _Whorl_ is no harder than the problem of how the averns'\nand the alzabo's ancestors got to Urth.\n\nOn the other hand, I think you could make a good case that it's not\nmuch easier for the inhumi to cross 35,000 leagues of space than ten\ntimes that distance.\n\nJerry Friedman" } ] }, { "message_id": "", "from": { "name": "Dan'l Danehy-Oakes", "address": "ddanehy at siebel.com" }, "date": "2002-03-14T22:27:38+00:00", "subject": "RE: (urth) Green's diameter, angular and otherwise", "in_reply_to": "", "reply_link": "subject", "blocks": [ { "kind": "text", "depth": 0, "text": "Jerry F., responding to me..." }, { "kind": "quote", "depth": 2, "text": "... for which I am frankly grateful, because it seems to me to drive the\nfinal nail into the \"Blue = Urth\" theory's coffin, based on past\ndiscussions herein." }, { "kind": "quote", "depth": 1, "text": "Okay, how? I too would be relieved, but I don't see the connection." }, { "kind": "text", "depth": 0, "text": "Well, maybe I was wrong from that perspective. I think the gravity issue\ndoes it, though..." }, { "kind": "quote", "depth": 2, "text": "A twin planet, or even the moon, seen at the distance of 105K\nmiles, would be rather too large for an \"eye\" to be, at any\nrate, the most obvious metaphor. " }, { "kind": "quote", "depth": 1, "text": "Au contraire, mon frere. Sundogs (mock suns, parhelia) have a good\ndeal more than twice the angular diameter of the moon, and one person\nwho talked to me about seeing one compared it repeatedly to God's eye\nlooking at her, perhaps accusingly. " }, { "kind": "text", "depth": 0, "text": "I can weasel this a bit, by observing that the ring makes the sundog _look_\nmuch more like an eye than a bright glowing round thing in the sky does,\nbut I accept your basic point." }, { "kind": "quote", "depth": 1, "text": "I think Marc just presented, not for the first time, cogent reasons\nto think that Green's gravity is less than the Earth's. " }, { "kind": "text", "depth": 0, "text": "I disagree. I suggest that the \"climbing with one arm while fighting with\nthe other\" bit is possible due to one or both of two things:\n\n1) This happens when the Narr is astrally travelling, not physical present\n on Green; and\n2) Dramatic/narrative convention; how many times have you seen this in\n the movies?" }, { "kind": "quote", "depth": 1, "text": "I argued a couple of days ago that nonetheless Green's gravity should be\nmuch greater than the moon's, more or less for the reason you mention. I\nagree with you and him that there's no trace of any difference between\nEarth's gravity, Urth's, Blue's, and the _Whorl's_ \"gravity\"." }, { "kind": "text", "depth": 0, "text": "Nor do I see any real evidence that Green's is any different." }, { "kind": "quote", "depth": 2, "text": "(BTW, the whole issue of the Fliers in a separate thread seems to miss \nthe point that they rarely - never voluntarily? - come near \"ground\" \nlevel.) " }, { "kind": "quote", "depth": 1, "text": "But they're capable of flying near ground level, at least for a little\nwhile. See Sciathan's discussion of his capture, if I remember it\ncorrectly." }, { "kind": "text", "depth": 0, "text": "Maybe I'm wrong, but I seem to recall his saying it's much more difficult\nnear the ground. " }, { "kind": "quote", "depth": 3, "text": "Anyway, the higher the true distance, the harder the problem of how\nthe inhumi cross." }, { "kind": "quote", "depth": 2, "text": "True, but in any event the problem of how the inhumi cross between\nBleen and Grue" }, { "kind": "quote", "depth": 1, "text": "(or Blee and Groon, for King Crimson fans)" }, { "kind": "text", "depth": 0, "text": "Well, I confess that I'm a 21st Century Schizoid Fan... " }, { "kind": "quote", "depth": 2, "text": "is trivial next to the problem of how Remora (and,\napparently, other inhumi) achieved the crossing to the Whorl. If I\nrecall correctly, a Neighbor mentions to Horn that they (the Neighbors)\nsent them (the inhumi) - but does not describe how this was done. " }, { "kind": "quote", "depth": 1, "text": "I don't see that. It's one of the problems the Blue=Ushas theory is\nsupposed to solve, and for those of us who don't believe that, there\nwas plenty of space travel before Typhon. The problem of how inhumi\ngot onto the _Whorl_ is no harder than the problem of how the averns'\nand the alzabo's ancestors got to Urth." }, { "kind": "text", "depth": 0, "text": "That seems to be based on an assumption that they were on the _Whorl_ \nfrom the time it left Urth, and I see no basis for that claim whatever. \nThe Neighbor's comment about sending the inhumi to the _Whorl_ seems to \nme to refer to a time after (probably just after) the _Whorl_'s arrival \nin the Glune system." }, { "kind": "quote", "depth": 1, "text": "On the other hand, I think you could make a good case that it's not\nmuch easier for the inhumi to cross 35,000 leagues of space than ten\ntimes that distance." }, { "kind": "text", "depth": 0, "text": "Shrug. Possibly. And actually, the distance to the _Whorl_ can't be\n_too_ much greater than the distance between the two planets, since the\n_Whorl_, which is certainly smaller than either of them, is plainly visible\nin the Bluvian night sky." } ] } ] }