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    A geography great circle question

    Which great circle that you can draw around the Earth passes through the most countries? In the way that the equator goes through 11? I don't know the answer and a cursory google doesn't seem to offer an immediate one either.

    #2
    https://nwhyte.livejournal.com/2929721.html

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      #3
      Originally posted by Nocturnal Submission View Post
      Bloody hell!

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        #4
        Bloody hell indeed, although the article kept jumping back to the top of the page on my iPad.

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          #5
          That's impressive forensic work though the latitude answers aren't technically great circles. I do wonder if his Togo-Tobago line was tilted slightly so more of South America then up through Africa into the Middle East and maybe then across the 'Stans, it would see the number of countries rocket.

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            #6
            I was previously unaware of the concept of lines of longitude and latitude having an appreciable width.

            Is that an Americanism? If so, does one create it by artificially limiting the number of decimal places used in degree measurements?

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              #7
              I understood the width thing was about "all the lines of longitude within this band" cross these countries

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                #8
                I must have read it too quickly. How does he define the band?

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                  #9
                  In fact there is quite a wide band, between the westernmost point of Bulgaria at 22°21'36.2"E, and the easternmost point of Slovakia at 22°33'32.1", which passes through no less than 26 countries.

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                    #10
                    Though obviously his excellent geographical nerdery there is somewhat undone by the use of "less" rather than "fewer"

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                      #11
                      Ah, now I get it.

                      I seem to be a bit slow this morning (see also the conflation between Fried Bread and Fried Dough)

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                        #12
                        I wish I could find a great circle mapper that would show the whole circle through two places rather than just the shorter arc. There's obviously many potential answers which are not through both poles.
                        Last edited by Kevin S; 25-02-2020, 14:22.

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                          #13
                          For example, the great circle through Malaga and Ho Chi Minh City looks like it has potential:
                          https://www.greatcirclemap.com/roadmap?routes=AGP-SGN

                          But you have to extrapolate the rest of the circle.

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                            #14
                            Originally posted by ursus arctos View Post
                            I was previously unaware of the concept of lines of longitude and latitude having an appreciable width.

                            Is that an Americanism? If so, does one create it by artificially limiting the number of decimal places used in degree measurements?
                            I was thrown by this as well – I was thinking surely any such line around the earth has no second dimension. Thanks ad hoc for making me realise that it's simply the limits within the same 26 (or whatever) countries are still crossed. That is, you could draw the circle at any point between the northernmost and southernmost (or westernmost and easternmost, depending) extremes of the 'bands' shown and it would still cross all the same countries; it isn't that it needs to have that width in order to cross them.

                            Anyway, that was an amazing piece of research. And is it just me, or is the "Togo-Tobago line" an incredibly satisfying name?

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                              #15
                              Originally posted by Kevin S View Post
                              For example, the great circle through Malaga and Ho Chi Minh City looks like it has potential:
                              https://www.greatcirclemap.com/roadmap?routes=AGP-SGN

                              But you have to extrapolate the rest of the circle.

                              Great website. Mucking around with it I found a route from Durban to Helsinki, taking in 22 countries. That increases to 24 when you continue north through Sweden and Norway, it's too much for my head to try and work out what happens when you go over the top and all the way around to complete the circle

                              https://www.greatcirclemap.com/roadm...tes=%20DUR-HEL

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                                #16
                                One of the amusing things about it is realising that for most pairs of places there is one route - the shorter arc of the great circle - that is the shortest. But if those places are antipodal then there's an infinite number of equal-distance routes. (This is of course when you model earth as a perfect sphere.)

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                                  #17
                                  And I think that one should take in 25 - can't really work out whether it's US (Alaska) or Russia with any accuracy or whether it gets anything else on the way.
                                  Last edited by Kevin S; 26-02-2020, 17:05.

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                                    #18
                                    Actually there's an outside chance of also picking up Kiribati and/or Cook Islands.

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                                      #19
                                      Originally posted by Nocturnal Submission View Post
                                      Cor!

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                                        #20
                                        Originally posted by Kevin S View Post
                                        One of the amusing things about it is realising that for most pairs of places there is one route - the shorter arc of the great circle - that is the shortest. But if those places are antipodal then there's an infinite number of equal-distance routes. (This is of course when you model earth as a perfect sphere.)
                                        Snake Plissken really ought to be able to write us a quick patch for OTF, an add-on so we key in a place name, and it automatically tells us its antipode, and all the variations of “great circle” from that axis, number of countries crossed etc.

                                        Shouldn’t be hard.

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                                          #21

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