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B History question -- The choice of the North Pole being up or down

  1. Jun 18, 2018 #1

    Grinkle

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    The choice of the North Pole being up on a map is arbitrary as far as I know.

    Is it that way because publishing cartographers came mostly from the northern hemisphere? Is there some reason related to navigation (like Polaris being over the north pole) that might motivate even a southern cartographer to draw the north pole up?

    Its a little odd to me that orbits end up being CCW with respect to north - but I think the order of things was round earth being a socially accepted fact before the planets orbiting the sun gained general acceptance, so CCW was pretty much baked in by that time.
     
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  3. Jun 18, 2018 #2

    fresh_42

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    That's the wrong starting point. You must go far back in time. All cultures had maps of their local area, but they are lost or haven't been found, yet. One of the first reliable sources is Ptolemy, a Greek philosopher sitting in Alexandria and drawing maps of his world, which was basically the Mediterranean sea and the areas around it, with some more information to the east and to the south of Egypt. This means he sat pretty much in the center west of his world. So what you're asking is mainly, why he drew Greece in the North and Egypt in the South, which is hard to tell. All other developments up to what we use nowadays are more or less a consequence of this decision, because knowledge has been copied and modified, not reinvented.

    If I'm allowed to speculate, then I assume he was right handed. So it made sense to draw the main parts of his map on the right side, which was east. The known world in the east and south was far bigger than in the west and north - seen from Alexandria. Of course this is a wild guess. To bad we can't ask him.
     
  4. Jun 18, 2018 #3

    davenn

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    who, the cultures or the maps ? :wink::-p

    sorry, I couldn't resist :smile: I'm so bad


    D
     
  5. Jun 19, 2018 #4

    Vanadium 50

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    Objection! Assumes facts not in evidence.

    If you look up what directions early maps had pointing up you will see south, east and north, and maybe even west.
     
  6. Jun 19, 2018 #5

    CWatters

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  7. Jun 19, 2018 #6

    Grinkle

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    @CWatters Thanks for that link. Here is a great quote from the section regarding Columbus putting East on top -

    We’ve got to remember, adds Brotton, that at the time, “no one knows what they are doing and where they are going”.

    An amusing if harsh retrospective. :-)
     
  8. Jun 19, 2018 #7

    CWatters

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    I liked Mercator's comment about North and nobody being interested in going there.
     
  9. Jun 19, 2018 #8

    stefan r

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  10. Jun 19, 2018 #9
    From an engineering and mathematical perspective CCW rotation is always viewed as positive as that is the direction of a vector rotating about the origin from 0 degrees towards 90 degrees and beyond. Since the Earth rotates CCW when viewed from above the North pole, it also makes sense that North is at the top. So, when viewing a distant galaxy, I guess that the direction of rotation could be used to determine "top" and "bottom". It is always useful to have these concepts, but, in principle, either CW or CCW could have been chosen.
     
  11. Jun 19, 2018 #10

    sophiecentaur

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    Having thought about this for a reasonable length of time, I have come to the conclusion that it could be to do with the Pole star Polaris. Polaris is always visible in the night sky and the rest of the stars appear to move in circles of varying radii around Polaris. That makes the pole star fairly significant and important to anyone trying to navigate. The 'North' direction actually relates to a particular, visible direction whereas the 'South' direction doesn't point to anything in particular. South is just 'Not North'. So North (for Europeans, at least) would have been an Important Direction.
    If you were drawing a map of a region, the bearings of features could easily be measured, relative to the North direction with a crude protractor type device. The North Reference would / could have been found at night and drawn as a permanent line on the ground (much like the meridian at Greenwich. If you were standing and taking bearings relative to this North direction, the North would be 'away from you' and at the top of the paper you were drawing on. That argument can be applied to directions at acute angles to the meridian and, once the convention had been established, it would have been used for all bearings.
    People who were trying to navigate in the day time might have tried using the Sun as a reference but they would have ended up 'walking in circles' which is a good way to get lost. Updating their bearing (relative to North) every night and using distant landmarks as interim direction markers would allow them (at walking pace) to keep going in a steady direction.
     
  12. Jun 19, 2018 #11

    Vanadium 50

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    Amazing. We know that early maps did not have north on top, but we're trying to explain why they did.
     
  13. Jun 20, 2018 #12

    sophiecentaur

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    That's PF for you. PF monkeys often end up in the right direction with their typewriters.
    I guess the 'real' question would have been about why the N at the top convention actually took hold. Apart from some of the tourist the town maps you can buy, the N at the top convention is pretty well established.
    The non-convention of very early maps is not really relevant because the choice of orientation would have been based on some ad hoc factor.
     
  14. Jun 20, 2018 #13

    Chronos

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    It was not just polaris, but, any number of bright circumpolar stars were popular navigational aids in ancient times. Early navigation devices included the cross staff and octant - which were precursors to the sextant. Navigation, however, was as much an art as science until accurate clocks became available. It was otherwise next to impossible to determine your longitude without knowledge of local geographical and oceanographic features. An experienced ship captain was in high demand and considered a respectable, albeit perilous profession The vikings learned to use the sunstone to locate the sun on overcast days. Despite stories to the contrary, ancient sea captains were already sold on the notion the earth was spherical, like the moon and sun. Navigational maps were unreliable ande pretty much existed only in the heads of seasoned ship captains until the later part of the 16th century.
     
  15. Jun 20, 2018 #14
    Exactly, navigation is the key. People in Europe in the Middle Ages preferred the "Orbis Terrarum" maps, showing the [inhabited part of the] World as letter T inscribed in O, with Jerusalem in the centre and east up. Asia was above the horizontal bar, Europe and Africa below, separated by vertical bar representing the Mediterranean Sea. Some of these maps were quite detailed, being more than symbolic representation of Christian world.

    But the actual need of maps showing realistic shorelines and relative distances between the ports emerged only with growing importance of sea trade. First accurate navigational charts ("portolans") were made during the Trecento (late Middle Ages in Italy). Their usage spread rapidly with the Age of Discovery. As they were of interest mostly to sea navigators, having north up was probably the most practical choice. Bright northern circumpolar stars are crucial in navigation in European waters, and the magnetic compass, that points (approximately) north, worked (almost) everywhere. It was useful especially on unknown waters, in the Old World other conventions were still in use.
     
  16. Jun 20, 2018 #15

    sophiecentaur

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    Polaris has its disadvantages in that it's way out in the middle of nowhere much and it is hard to identify amidst patchy cloud. There are star patterns that are much easier to identify in a brief glimpse. However, I would suggest that any celestial marker that was used would have been visible for all the year - or they would have needed to have a separate set of rules for the different seasons. As they say "life's complicated enough'.
    Direction of a course or bearing was easy. Latitude was pretty straightforward. Longitude was only truly sorted when reliable chronographs were available - but there were (poorer) alternative methods based on Lunar observation and looking at the jovian moons.
    But I was not suggesting that earliest navigators would have been in ships. Navigating on land also requires a good idea of direction and it's a much more stable situation. I would have thought that the basics would have been developed long before any sea navigation except for coastal hopping.
     
  17. Jun 20, 2018 #16
    Land navigation requires detailed knowledge of landmarks, orientation points, which are usually plentiful. Early maps could be highly distorted, and they usually were, as long as they showed a particular mountain, town, or castle, in proper order. If we could attribute orientation to such map, most probably it would be related to the travelling direction, or the shore, or something as notable.

    If you think about covering large distances across monotonous landscape (desert, steppe), then the preferred orientation would be related to Sun's path. People tend to travel during the day, so they usually oriented themselves relative to the point where the Sun rises – the East. By the way, that's why we call the procedure "orientation".
     
  18. Jun 20, 2018 #17

    sophiecentaur

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    I think we're making some of this up as we go along (mea culpa too) but we are trying to find a reason why N was chosen and not the way people started to navigate. The fact is that it was. We should bear in mind that Polaris is, even now, used in astronomy to orientate an Equatorial Mount and that the celestial sphere is all based with N as the origin. Pointing my telescope involves referring it to the Celestial North Pole. Without help from a Goto Mount or even a magnetic compass, I would need to look at Polaris (with possibly some correction for its real position) and move around to get Right Ascension and declination to find a wanted star. I would be standing, looking North to start with (top of my sheet of paper.
    Having done a bit of both navigation and stargazing I could be biased in favour of the conventional system and I could just be post hoc rationalising but, once it was decided that having maps all aligned the same way (for obvious reasons) then aligning them up with something that is in common with most people (before the New World was a player in this) would have made sense. Choosing something that stays still in the sky would make perfect sense. Using the Sun as a navigation reference is extremely risky because its position (of course) changes throughout the day. Its highest point in the sky would be a reliable South reference but you would need to be waiting and plotting its elevation for several hours every day (without a watch to tell you when to be looking).
    Interestingly, East and West are often swapped on star charts and a Planisphere because they are designed to be used, held up above your head. In a way, that justifies my N/S thesis on the grounds that the orientation is based on the way such maps are actually used.
     
  19. Jun 21, 2018 #18
    I've made a mental shortcut – "orientation" does come from "Orient", but through early maps, not directly from early travellers. Besides that, I too tried to find the reason why N is now up on most maps and when it started to be so. As for celestial maps, that question is indeed simpler; the Pole Star is the only obvious point of reference in northern mid-latitudes, since everything else is in motion, and it always hangs high above the head, unlike the zodiac constellations. The latitude of majority of observers was the most important factor, as for ancient stargazers in low latitudes like Maya or Polynesians, things looked much different. All sky revolved around them, and moderately bright Polaris lying low near the horizon wasn't that important. They paid more attention to great circles in the sky like the Milky Way; it had reflection in their cosmology and beliefs.
     
  20. Jun 21, 2018 #19

    sophiecentaur

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