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Will Solar Eclipses Occur on 8 April 2005 and 3 November 2005? |
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| Mar1-05, 02:32 PM | #1 |
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Will Solar Eclipses Occur on 8 April 2005 and 3 November 2005?
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Hi all,\n\nA few days ago I happened across an essay by the late Stephen Jay Gould\ndescribing his observations of "ordinary New Yorkers" observing a near\ntotal solar eclipse visible from that city (some decades ago). This\nreminded me of a question that I had been meaning to ask here for\nseveral months, but hadn\'t gotten around to. Here it is:\n\nOn 8 April 2005, it seems that a complete or nearly complete solar\neclipse should be visible from the Pitcairn Islands, with closest\napproach to totality occurring at 11:49 AM local time, at an elevation\nof about 55 degrees from the horizon. The same eclipse should in\nprinciple be marginally visible near Balboa, Panama, with closest\napproach to totality occuring at 5:13 PM local time--- but of course,\ntoo low in the sky, arghghgh, to be really suitable for observation. An\ninteresting feature of this eclipse is that Venus should be visible only\ntwo degrees away, which should further add to the drama of the event.\nAre these predictions correct?\n\nOn 3 November 2005, it seems that a complete or nearly complete solar\neclipse should be visible near Avila, Spain, with closest approach to\ntotality occuring at 10:58 AM local time. Is this prediction correct?\nWill these in fact be -complete- solar eclipses?\n\nI also have two postdictions concerning historical events which I don\'t\nhave enough historical information to verify myself.\n\nOn 21 September 1922, according to Misner, Thorne, & Wheeler,\nGravitation, 1973 (this just happened to be the only book I had at hand\nwhich contains any information at all about historical eclipses!), a\ntotal solar eclipse was visible in Western Australia. Indeed, it seems\nthat the closest approach to totality, as seen from the vicinity of\nAlice Springs, would have occured at 3:25 PM local time. Is this\ncorrect?\n\nOn 8 April 2005, as we probably all remember, there occured a transit of\nVenus across the visible solar disk. It seems that, weather permitting,\nthis would have been visible from the island of Diego Garcia from about\n9:30 AM to 3 PM local time. Is this correct?\n\n"T. Essel" (virtually stargazing, somewhere in cyberspace)\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Hi all,
A few days ago I happened across an essay by the late Stephen Jay Gould describing his observations of "ordinary New Yorkers" observing a near total solar eclipse visible from that city (some decades ago). This reminded me of a question that I had been meaning to ask here for several months, but hadn't gotten around to. Here it is: On 8 April 2005, it seems that a complete or nearly complete solar eclipse should be visible from the Pitcairn Islands, with closest approach to totality occurring at 11:49 AM local time, at an elevation of about 55 degrees from the horizon. The same eclipse should in principle be marginally visible near Balboa, Panama, with closest approach to totality occuring at 5:13 PM local time--- but of course, too low in the sky, arghghgh, to be really suitable for observation. An interesting feature of this eclipse is that Venus should be visible only two degrees away, which should further add to the drama of the event. Are these predictions correct? On 3 November 2005, it seems that a complete or nearly complete solar eclipse should be visible near Avila, Spain, with closest approach to totality occuring at 10:58 AM local time. Is this prediction correct? Will these in fact be -complete- solar eclipses? I also have two postdictions concerning historical events which I don't have enough historical information to verify myself. On 21 September 1922, according to Misner, Thorne, & Wheeler, Gravitation, 1973 (this just happened to be the only book I had at hand which contains any information at all about historical eclipses!), a total solar eclipse was visible in Western Australia. Indeed, it seems that the closest approach to totality, as seen from the vicinity of Alice Springs, would have occured at 3:25 PM local time. Is this correct? On 8 April 2005, as we probably all remember, there occured a transit of Venus across the visible solar disk. It seems that, weather permitting, this would have been visible from the island of Diego Garcia from about 9:30 AM to 3 PM local time. Is this correct? "T. Essel" (virtually stargazing, somewhere in cyberspace) |
| Mar2-05, 01:04 AM | #2 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>In article <d02jga\\$q9o\\$1@fiasco.xenopsyche.net>, wrote:\n> On 8 April 2005, it seems that a complete or nearly complete solar\n> eclipse should be visible from the Pitcairn Islands,\n[SNIP]\n> An\n> interesting feature of this eclipse is that Venus should be visible only\n> two degrees away, which should further add to the drama of the event.\n> Are these predictions correct?\n>\n\nIf you are wanting serious information about past/ present/ future\neclipses, then the SunEarth site at NASA is a very good start :\nhttp://sunearth.gsfc.nasa.gov/eclipse/eclipse.html\nFollowing links there, I see that :\n> The path of this event begins as an annular eclipse but it changes to\n> total about 2200 km south of Tahiti. At maximum eclipse (UT), the\n> duration of totality is 45 seconds. Unfortunately, the total portion\n> of the track never crosses land. The path becomes annular again about\n> 800 km west of Costa Rica. By the time the shadow reaches the coast\n> of Costa Rica, the annular phase will already be 12 seconds and\n> growing. After crossing Panama and Colombia, the central path ends\n> in Venezuela where a 33 second annular eclipse will occur at sunset.\n>\n\n> On 3 November 2005, it seems that a complete or nearly complete solar\n> eclipse should be visible near Avila, Spain, with closest approach to\n> totality occuring at 10:58 AM local time.\n>\nErr, my friends \'Ammonite\' and the \'MudSharks\' were finalising\narrangements for this a few months ago. I thought they were talking about\nOCTOBER 2005. Again, to NASA\'s pages:\n> On Monday, October 03, an annular eclipse of the Sun will be visible\n> from within a narrow corridor which traverses the Iberian Peninsula\n> and stretches across the African continent. A partial eclipse will\n> be seen within the much broader path of the Moon\'s penumbral shadow,\n> which includes Europe, western Asia, the Middle East, India and most\n> of Africa.\nso my friend\'s plans appear to be in the correct month.\n\n> On 8 April 2005, as we probably all remember, there occured a transit of\n> Venus across the visible solar disk.\n>\nHuh? Have you got your calendar open at the right page?\n\nI think you need to do some reading at the NASA site I cited\nabove. It\'s technically accurate. I used it to plan my eclipse photography\nin \'99 and I got a diamond ring where my father got rained on.\n\n--\nAidan Karley,\nAberdeen, Scotland,\nLocation: 57°10\'11" N, 02°08\'43" W (sub-tropical Aberdeen), 0.021233\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>In article <d02jga$q9o$1@fiasco.xenopsyche.net>, wrote:
> On 8 April 2005, it seems that a complete or nearly complete solar > eclipse should be visible from the Pitcairn Islands, [SNIP] > An > interesting feature of this eclipse is that Venus should be visible only > two degrees away, which should further add to the drama of the event. > Are these predictions correct? > If you are wanting serious information about [itex]past/[/itex] present/ future eclipses, then the SunEarth site at NASA is a very good start : http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html Following links there, I see that : > The path of this event begins as an annular eclipse but it changes to > total about 2200 km south of Tahiti. At maximum eclipse (UT), the > duration of totality is 45 seconds. Unfortunately, the total portion > of the track never crosses land. The path becomes annular again about > 800 km west of Costa Rica. By the time the shadow reaches the coast > of Costa Rica, the annular phase will already be 12 seconds and > growing. After crossing Panama and Colombia, the central path ends > in Venezuela where a 33 second annular eclipse will occur at sunset. > > On 3 November 2005, it seems that a complete or nearly complete solar > eclipse should be visible near Avila, Spain, with closest approach to > totality occuring at 10:58 AM local time. > Err, my friends 'Ammonite' and the 'MudSharks' were finalising arrangements for this a few months ago. I thought they were talking about OCTOBER 2005. Again, to NASA's pages: > On Monday, October 03, an annular eclipse of the Sun will be visible > from within a narrow corridor which traverses the Iberian Peninsula > and stretches across the African continent. A partial eclipse will > be seen within the much broader path of the Moon's penumbral shadow, > which includes Europe, western Asia, the Middle East, India and most > of Africa. so my friend's plans appear to be in the correct month. > On 8 April 2005, as we probably all remember, there occured a transit of > Venus across the visible solar disk. > Huh? Have you got your calendar open at the right page? I think you need to do some reading at the NASA site I cited above. It's technically accurate. I used it to plan my eclipse photography in '99 and I got a diamond ring where my father got rained on. -- Aidan Karley, Aberdeen, Scotland, Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), .021233 |
| Mar3-05, 04:27 PM | #3 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Wed, 2 Mar 2005, Aidan Karley wrote:\n\n>> The path of this event begins as an annular eclipse but it changes to\n>> total about 2200 km south of Tahiti. At maximum eclipse (UT), the\n>> duration of totality is 45 seconds. Unfortunately, the total portion of\n>> the track never crosses land. The path becomes annular again about 800\n>> km west of Costa Rica. By the time the shadow reaches the coast of\n>> Costa Rica, the annular phase will already be 12 seconds and growing.\n>> After crossing Panama and Colombia, the central path ends in Venezuela\n>> where a 33 second annular eclipse will occur at sunset.\n\nCool!!!\n\n>> On 3 November 2005, it seems that a complete or nearly complete solar\n>> eclipse should be visible near Avila, Spain, with closest approach to\n>> totality occuring at 10:58 AM local time.\n\n> Err, my friends \'Ammonite\' and the \'MudSharks\' were finalising\n> arrangements for this a few months ago. I thought they were talking\n> about OCTOBER 2005. Again, to NASA\'s pages:\n\nOops, month 10 is October, not November, iddnt? :-/\n\n>> On Monday, October 03, an annular eclipse of the Sun will be visible\n>> from within a narrow corridor which traverses the Iberian Peninsula\n\nCool, an annular eclipse!\n\n>> and stretches across the African continent. A partial eclipse will\n>> be seen within the much broader path of the Moon\'s penumbral shadow,\n>> which includes Europe, western Asia, the Middle East, India and most\n>> of Africa.\n\n>> On 8 April 2005, as we probably all remember, there occured a transit of\n>> Venus across the visible solar disk.\n\nEr, 2004? ;-/\n\nThanks, Aidan! This is just what I wanted!\n\n"T. Essel" (hiding somewhere in cyberspace)\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Wed, 2 Mar 2005, Aidan Karley wrote:
>> The path of this event begins as an annular eclipse but it changes to >> total about 2200 km south of Tahiti. At maximum eclipse (UT), the >> duration of totality is 45 seconds. Unfortunately, the total portion of >> the track never crosses land. The path becomes annular again about 800 >> km west of Costa Rica. By the time the shadow reaches the coast of >> Costa Rica, the annular phase will already be 12 seconds and growing. >> After crossing Panama and Colombia, the central path ends in Venezuela >> where a 33 second annular eclipse will occur at sunset. Cool!!! >> On 3 November 2005, it seems that a complete or nearly complete solar >> eclipse should be visible near Avila, Spain, with closest approach to >> totality occuring at 10:58 AM local time. > Err, my friends 'Ammonite' and the 'MudSharks' were finalising > arrangements for this a few months ago. I thought they were talking > about OCTOBER 2005. Again, to NASA's pages: Oops, month 10 is October, not November, iddnt[itex]? :-/[/itex] >> On Monday, October 03, an annular eclipse of the Sun will be visible >> from within a narrow corridor which traverses the Iberian Peninsula Cool, an annular eclipse! >> and stretches across the African continent. A partial eclipse will >> be seen within the much broader path of the Moon's penumbral shadow, >> which includes Europe, western Asia, the Middle East, India and most >> of Africa. >> On 8 April 2005, as we probably all remember, there occured a transit of >> Venus across the visible solar disk. Er, 2004[itex]? ;-/[/itex] Thanks, Aidan! This is just what I wanted! "T. Essel" (hiding somewhere in cyberspace) |
| Mar4-05, 09:15 AM | #4 |
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Will Solar Eclipses Occur on 8 April 2005 and 3 November 2005?
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>in article VA.00000584.0f49f72d@mynameplus1.demon.co.uk.invalid, Aidan\nKarley at aidan@mynameplus1.demon.co.uk.invalid wrote on 03/02/2005 02:04:\n\n> If you are wanting serious information about past/ present/ future\n> eclipses, then the SunEarth site at NASA is a very good start :\n> http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html\n> Following links there, I see that :\n>> The path of this event begins as an annular eclipse but it changes to\n>> total about 2200 km south of Tahiti. At maximum eclipse (UT), the\n>> duration of totality is 45 seconds. Unfortunately, the total portion\n>> of the track never crosses land. The path becomes annular again about\n>> 800 km west of Costa Rica. By the time the shadow reaches the coast\n>> of Costa Rica, the annular phase will already be 12 seconds and\n>> growing. After crossing Panama and Colombia, the central path ends\n>> in Venezuela where a 33 second annular eclipse will occur at sunset.\n\nhow does an annular eclipse only last for 33 seconds. i s\'pose there is\nonly one instant of time when the moon is perfectly smack-dab in front of\nthe sun (if it is at all), but if you allow any slop in the definition of\nthe elapsed time of the eclipse, isn\'t it longer than that?\n\nwhen i lived in Hanover NH in 1993 and 94, in one of those years (i think it\nwas 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse\nof the sun) and it lasted for longer than that as i recall.\n\n--\n\nr b-j rbj@audioimagination.com\n\n"Imagination is more important than knowledge."\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>in article VA.00000584.0f49f72d@mynameplus1.demon.co.uk.invalid, Aidan
Karley at aidan@mynameplus1.demon.co.uk.invalid wrote on [itex]03/02/2005 02:04:[/itex] > If you are wanting serious information about [itex]past/[/itex] present/ future > eclipses, then the SunEarth site at NASA is a very good start : > http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html > Following links there, I see that : >> The path of this event begins as an annular eclipse but it changes to >> total about 2200 km south of Tahiti. At maximum eclipse (UT), the >> duration of totality is 45 seconds. Unfortunately, the total portion >> of the track never crosses land. The path becomes annular again about >> 800 km west of Costa Rica. By the time the shadow reaches the coast >> of Costa Rica, the annular phase will already be 12 seconds and >> growing. After crossing Panama and Colombia, the central path ends >> in Venezuela where a 33 second annular eclipse will occur at sunset. how does an annular eclipse only last for 33 seconds. i s'pose there is only one instant of time when the moon is perfectly smack-dab in front of the sun (if it is at all), but if you allow any slop in the definition of the elapsed time of the eclipse, isn't it longer than that? when i lived in Hanover NH in 1993 and 94, in one of those years (i think it was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse of the sun) and it lasted for longer than that as i recall. -- [itex]r b-j[/itex] rbj@audioimagination.com "Imagination is more important than knowledge." |
| Mar6-05, 01:49 AM | #5 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>In article <BE4D7D4A.4F8D%rbj@audioimagination.com>, robert\nbristow-johnson <rbj@audioimagination.com> writes:\n\n> how does an annular eclipse only last for 33 seconds. i s\'pose there is\n> only one instant of time when the moon is perfectly smack-dab in front of\n> the sun (if it is at all), but if you allow any slop in the definition of\n> the elapsed time of the eclipse, isn\'t it longer than that?\n>\n> when i lived in Hanover NH in 1993 and 94, in one of those years (i think it\n> was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse\n> of the sun) and it lasted for longer than that as i recall.\n\nConsider how unlikely an eclipse is in the first place. It\'s not so\nunlikely that the Moon passes in front of the Sun, since the entire\nsolar system is essentially in the same plane (it\'s about as flat as a\npizza box). However, it is rather unlikely that the Moon is the same\napparent size as the Sun. Earth\'s Moon is unusually large, compared to\nthe size of the planet it orbits. (There are larger moons, but the\nplanets they orbit are giants, so that in relation they are smaller.)\nThe same apparent size could come from a smaller Moon closer in, but it\nwould travel faster and the length of an eclipse would be much shorter.\nA larger Moon further out would be better, but then the Moon would be\neven larger with respect to the Earth.\n\nThis is even more astounding since the Moon is moving away from the\nEarth (tidal friction slows down the Earth, and the Moon moves out to\ncompensate, conserving angular momentum). In the past, there was a long\ntime when there were no solar eclipses, and there will be a long time in\nthe future when there will also be no solar eclipses.\n\nThe Moon\'s orbit isn\'t exactly circular, so the exact distance varies a\nbit from eclipse to eclipse, and thus the apparent size. If the Moon is\ntoo far away, we get an annular eclipse. All things being equal, the\nfurther away, the longer the (annular) eclipse will last. Also, the\nmore exact the alignment, the longer the eclipse. Also, the Earth is\nspinning underneath, faster at the equator than at the poles, so the\nlength will depend on latitude and, since the transverse velocity is the\nimportant one, also on the time of day.\n\nThus, the length of an eclipse varies from 0 to about 7 minutes.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>In article <BE4D7D4A.4F8D%rbj@audioimagination.com>, robert
bristow-johnson <rbj@audioimagination.com> writes: > how does an annular eclipse only last for 33 seconds. i s'pose there is > only one instant of time when the moon is perfectly smack-dab in front of > the sun (if it is at all), but if you allow any slop in the definition of > the elapsed time of the eclipse, isn't it longer than that? > > when i lived in Hanover NH in 1993 and 94, in one of those years (i think it > was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse > of the sun) and it lasted for longer than that as i recall. Consider how unlikely an eclipse is in the first place. It's not so unlikely that the Moon passes in front of the Sun, since the entire solar system is essentially in the same plane (it's about as flat as a pizza box). However, it is rather unlikely that the Moon is the same apparent size as the Sun. Earth's Moon is unusually large, compared to the size of the planet it orbits. (There are larger moons, but the planets they orbit are giants, so that in relation they are smaller.) The same apparent size could come from a smaller Moon closer in, but it would travel faster and the length of an eclipse would be much shorter. A larger Moon further out would be better, but then the Moon would be even larger with respect to the Earth. This is even more astounding since the Moon is moving away from the Earth (tidal friction slows down the Earth, and the Moon moves out to compensate, conserving angular momentum). In the past, there was a long time when there were no solar eclipses, and there will be a long time in the future when there will also be no solar eclipses. The Moon's orbit isn't exactly circular, so the exact distance varies a bit from eclipse to eclipse, and thus the apparent size. If the Moon is too far away, we get an annular eclipse. All things being equal, the further away, the longer the (annular) eclipse will last. Also, the more exact the alignment, the longer the eclipse. Also, the Earth is spinning underneath, faster at the equator than at the poles, so the length will depend on latitude and, since the transverse velocity is the important one, also on the time of day. Thus, the length of an eclipse varies from to about 7 minutes. |
| Mar6-05, 01:51 AM | #6 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>robert bristow-johnson wrote:\n> how does an annular eclipse only last for 33 seconds. i s\'pose there is\n> only one instant of time when the moon is perfectly smack-dab in front of\n> the sun (if it is at all), but if you allow any slop in the definition of\n> the elapsed time of the eclipse, isn\'t it longer than that?\n>\n> when i lived in Hanover NH in 1993 and 94, in one of those years (i think it\n> was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse\n> of the sun) and it lasted for longer than that as i recall.\n>\n\nIf the sun and moon have exactly the same angular size, the moon will\nexactly cover the sun, and the eclipse duration will be zero seconds.\nIt gets longer on either side.\n\nCheers,\n\nPhil Hobbs\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>robert bristow-johnson wrote:
> how does an annular eclipse only last for 33 seconds. i s'pose there is > only one instant of time when the moon is perfectly smack-dab in front of > the sun (if it is at all), but if you allow any slop in the definition of > the elapsed time of the eclipse, isn't it longer than that? > > when i lived in Hanover NH in 1993 and 94, in one of those years (i think it > was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse > of the sun) and it lasted for longer than that as i recall. > If the sun and moon have exactly the same angular size, the moon will exactly cover the sun, and the eclipse duration will be zero seconds. It gets longer on either side. Cheers, Phil Hobbs |
| Mar6-05, 01:53 AM | #7 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>In article <BE4D7D4A.4F8D%rbj@audioimagination.com>, Robert\nbristow-johnson wrote:\n> how does an annular eclipse only last for 33 seconds.\n>\nThe last part of the eclipse (anything after 33 seconds) is\ninvisible due to the sun going below the horizon. There are quite\nlikely some assumptions about the levelness of the horizon there, the\nair\'s refractive index (temperature?) ,and other stuff.\n\n--\nAidan Karley,\nAberdeen, Scotland,\nLocation: 57=B010\'11" N, 02=B008\'43" W (sub-tropical Aberdeen), 0.0212=\n33\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>In article <BE4D7D4A.4F8D%rbj@audioimagination.com>, Robert
bristow-johnson wrote: > how does an annular eclipse only last for 33 seconds. > The last part of the eclipse (anything after 33 seconds) is invisible due to the sun going below the horizon. There are quite likely some assumptions about the levelness of the horizon there, the air's refractive index (temperature?) ,and other stuff. -- Aidan Karley, Aberdeen, Scotland, Location: [itex]57=B010'11[/itex]" N, [itex]02=B008'43[/itex]" W (sub-tropical Aberdeen), .[itex]0212=[/itex] 33 |
| Mar6-05, 01:55 AM | #8 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>"robert bristow-johnson" <rbj@audioimagination.com> wrote in message\nnews:BE4D7D4A.4F8D%rbj@audioimagination.com...\n> in article VA.00000584.0f49f72d@mynameplus1.demon.co.uk.invalid, Aidan\n> Karley at aidan@mynameplus1.demon.co.uk.invalid wrote on 03/02/2005 02:04:\n>\n>> If you are wanting serious information about past/ present/ future\n>> eclipses, then the SunEarth site at NASA is a very good start :\n>> http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html\n>> Following links there, I see that :\n>>> The path of this event begins as an annular eclipse but it changes to\n>>> total about 2200 km south of Tahiti. At maximum eclipse (UT), the\n>>> duration of totality is 45 seconds. Unfortunately, the total portion\n>>> of the track never crosses land. The path becomes annular again about\n>>> 800 km west of Costa Rica. By the time the shadow reaches the coast\n>>> of Costa Rica, the annular phase will already be 12 seconds and\n>>> growing. After crossing Panama and Colombia, the central path ends\n>>> in Venezuela where a 33 second annular eclipse will occur at sunset.\n>\n> how does an annular eclipse only last for 33 seconds. i s\'pose there is\n> only one instant of time when the moon is perfectly smack-dab in front of\n> the sun (if it is at all), but if you allow any slop in the definition of\n> the elapsed time of the eclipse, isn\'t it longer than that?\n\nNo, an annular is when the sun appears as a ring surrounding the Moon, and it\nmay last a couple of minutes to as short as a second or so. The length depends\non the apparent size of the Moon; the smaller the size, the longer the annular.\n\n\n> when i lived in Hanover NH in 1993 and 94, in one of those years (i think it\n> was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse\n> of the sun) and it lasted for longer than that as i recall.\n\nI believe "total" only refers to those cases where apparent size of the Moon is\nlarge enough to cover the entire disk of the Sun. These are the ones where you\nsee the Corona of the Sun around the dark disk of the Moon. With an annular,\neven that little bit of the Sun peeking around the edge of the Moon is\nsufficient to prevent you from seeing the Corona.\n--\nSincerely,\n--- Dave\n----------------------------------------------------------------------\nIt don\'t mean a thing\nunless it has that certain "je ne sais quoi"\nDuke Ellington\n----------------------------------------------------------------------\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>"robert bristow-johnson" <rbj@audioimagination.com> wrote in message
news:BE4D7D4A.4F8D%rbj@audioimagination.com... > in article VA.00000584.0f49f72d@mynameplus1.demon.co.uk.invalid, Aidan > Karley at aidan@mynameplus1.demon.co.uk.invalid wrote on [itex]03/02/2005 02:04:[/itex] > >> If you are wanting serious information about [itex]past/[/itex] present/ future >> eclipses, then the SunEarth site at NASA is a very good start : >> http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html >> Following links there, I see that : >>> The path of this event begins as an annular eclipse but it changes to >>> total about 2200 km south of Tahiti. At maximum eclipse (UT), the >>> duration of totality is 45 seconds. Unfortunately, the total portion >>> of the track never crosses land. The path becomes annular again about >>> 800 km west of Costa Rica. By the time the shadow reaches the coast >>> of Costa Rica, the annular phase will already be 12 seconds and >>> growing. After crossing Panama and Colombia, the central path ends >>> in Venezuela where a 33 second annular eclipse will occur at sunset. > > how does an annular eclipse only last for 33 seconds. i s'pose there is > only one instant of time when the moon is perfectly smack-dab in front of > the sun (if it is at all), but if you allow any slop in the definition of > the elapsed time of the eclipse, isn't it longer than that? No, an annular is when the sun appears as a ring surrounding the Moon, and it may last a couple of minutes to as short as a second or so. The length depends on the apparent size of the Moon; the smaller the size, the longer the annular. > when i lived in Hanover NH in 1993 and 94, in one of those years (i think it > was 94), i saw a total annular eclipse (i wish it was a total-TOTAL eclipse > of the sun) and it lasted for longer than that as i recall. I believe "total" only refers to those cases where apparent size of the Moon is large enough to cover the entire disk of the Sun. These are the ones where you see the Corona of the Sun around the dark disk of the Moon. With an annular, even that little bit of the Sun peeking around the edge of the Moon is sufficient to prevent you from seeing the Corona. -- Sincerely, --- Dave ---------------------------------------------------------------------- It don't mean a thing unless it has that certain "je ne sais quoi" Duke Ellington ---------------------------------------------------------------------- |
| Mar7-05, 09:55 AM | #9 |
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<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>In message <VA.00000584.0f49f72d@mynameplus1.demon.co.uk.invalid>, Aidan\nKarley <aidan@mynameplus1.demon.co.uk.invalid> writes\n>In article <d02jga\\$q9o\\$1@fiasco.xenopsyche.net>, wrote:\n\n>> On 3 November 2005, it seems that a complete or nearly complete solar\n>> eclipse should be visible near Avila, Spain, with closest approach to\n>> totality occuring at 10:58 AM local time.\n>>\n> Err, my friends \'Ammonite\' and the \'MudSharks\' were finalising\n>arrangements for this a few months ago. I thought they were talking about\n>OCTOBER 2005. Again, to NASA\'s pages:\n>.\n\nThis thread should probably be on an unmoderated group, but here goes!\n"Finalising"? I haven\'t started planning yet, apart from marking the\ndate :-)\nWhere do they plan to go?\n--\nMail to jsilverlight AT merseia DOT fsnet DOT co DOT uk is welcome.\n\n\n--\nNo virus found in this outgoing message.\nChecked by AVG Anti-Virus.\nVersion: 7.0.308 / Virus Database: 266.6.0 - Release Date: 02/03/2005\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>In message <VA.00000584.0f49f72d@mynameplus1.demon.co.uk.invalid>, Aidan
Karley <aidan@mynameplus1.demon.co.uk.invalid> writes >In article <d02jga$q9o$1@fiasco.xenopsyche.net>, wrote: >> On 3 November 2005, it seems that a complete or nearly complete solar >> eclipse should be visible near Avila, Spain, with closest approach to >> totality occuring at 10:58 AM local time. >> > Err, my friends 'Ammonite' and the 'MudSharks' were finalising >arrangements for this a few months ago. I thought they were talking about >OCTOBER 2005. Again, to NASA's pages: >. This thread should probably be on an unmoderated group, but here goes! "Finalising"? I haven't started planning yet, apart from marking the date :-) Where do they plan to go? -- Mail to jsilverlight AT merseia DOT fsnet DOT co DOT uk is welcome. -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7..308 / Virus Database: 266.6. - Release Date: [itex]02/03/2005[/itex] |
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