Hello Edley and listeners everywhere, Edley, I don't quite know how to answer you. I explained in an earlier message that this was a real question set for airline pilots but it was fifty eight years ago and the exact wording unfortunately eludes me. Did they have nanoseconds then? And what about refraction, parallax and height of eye? Is Paris higher than London? It looks lower on the map.
Which reminds me that the south east of England is running out of water. We have plenty here in the north and the good folks of London are under the impression that if they built a pipe the water would just run down to them. After all, we are at the top of our English maps and they are at the bottom. Frank 55N 1W Edley McKnight wrote: >Hello Franks and all, > >I assume we are to neglect altitude differences and use the fictional >spherical earth model, but just what do we mean by 'the same time'? I >would assume that when two or more persons look at their watches, >corrected for standard zone time, that they read the same numbers? If so, >this would give a larger number of answers as the sun sets in each time >zone, it will probably occur some place within it at the same clock time as in >fixed places in other time zones. Something like the New Year always starts >at midnight, so each time zone has it's own New Year, 24 in total. Since the >time zones are so non-uniform, the problem could be quite difficult to solve. >But you probably mean at the same GMT or Universal time. Then we have >our troubles with synchronizing. Given that light travels at about 11.8 >inches in a nanosecond, someone 11.8 feet away would be off by 12 >nanoseconds. Still, the problem is a neat one! > >Having fun with Sundials! > >Edley. > > > >>Greetings, fellow dialists, >> >>A little while ago there was a dialling discussion about pairs of places >>where the sun rose or set at the same moment. I recall that to solve the >>problem a "terminator" programme was called into play. >> >>There are earlier examples of this question. Around the year 1950 >>airline pilots (who still used sextants) sat two successive navigation >>examinations, the higher of which was called the First N. In the written >>paper a question appeared of the form: >> >>"Find a day on which the sun sets (altitude 0 deg.) at the same moment >>in London and Paris (positions given)." >> >>This problem caused the pilots much head scratching until it was >>realised that this type of question occurred in every paper that was >>set. The solution is presumably a simultaneous equation in spherical >>trigonometry to discover the sun's declination. >> >>Would any dialist care to try it? >>Frank >>55N 1W >> >> >> >>-- >>No virus found in this outgoing message. >>Checked by AVG Free Edition. >>Version: 7.5.472 / Virus Database: 269.9.0/852 - Release Date: 17/06/2007 >>08:23 >> >> >>--------------------------------------------------- >>https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> > > > > > >------------------------------------------------------------------------ > >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.5.472 / Virus Database: 269.9.1/854 - Release Date: 19/06/2007 13:12 > > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.472 / Virus Database: 269.9.1/854 - Release Date: 19/06/2007 13:12 --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
