Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: myuncle on 28/04/2018 20:13:24
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Let's say we conquer in the future a new planet in a far galaxy. How to decide where is north and south in the maps? And how this was decided on our planet maps? If we put our maps upside down after all, it wouldn't make any difference.
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The direction of up for North for our maps likely is due to the fact that the civilizations that went on to have the most influence arose in the Northern hemisphere. And from there, you see the night sky revolve around a fixed point in the sky near Polaris. This made Polaris an important fixture for navigation. Since we associate "UP" with priority , it made sense to make the direction of the North star "up" on maps.
On another planet, I'll go out on a limb and guess that the rotation of the planet will become the deciding factor. We are so used to the idea of the Sun rising in the East and setting in the West, that we will likely orient our maps for that world in order to maintain this.
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The direction of up for North for our maps likely is due to the fact that the civilizations that went on to have the most influence arose in the Northern hemisphere. And from there, you see the night sky revolve around a fixed point in the sky near Polaris. This made Polaris an important fixture for navigation. Since we associate "UP" with priority , it made sense to make the direction of the North star "up" on maps.
On another planet, I'll go out on a limb and guess that the rotation of the planet will become the deciding factor. We are so used to the idea of the Sun rising in the East and setting in the West, that we will likely orient our maps for that world in order to maintain this.
interesting. So mainly it depends on the fact the the first people drawing maps were living in the northern emisphere (mediterranean sea)?
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Interesting topic.
I wonder to what extent the fact that the Sun rose and set in the East and West respectively, meaning that the North and South were relative constants, also made a contribution to this decision? Then, as others have alluded to, navigational aids like the North Star would have also had a bearing (sorry!) on the situation. And once the decision was made by the first adopters, who were from the northern hemisphere, t set the standard followed by everyone since...
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I wonder to what extent the fact that the Sun rose and set in the East and West respectively, meaning that the North and South were relative constants, also made a contribution to this decision?
I think you are right. Rising and setting of the sun would be important events, but clearly variable in position. What I do wonder is whether pole star was spotted first or the fact that shortest shadow of a tree, stick, etc always points north - midday - in the Mediterranean area.
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I wonder to what extent the fact that the Sun rose and set in the East and West respectively, meaning that the North and South were relative constants, also made a contribution to this decision?
The designation of North must have preceded the identification of East and West as orient and occident.
If what is now considered the South pole had originally been called the North pole, and had been defined as “up”; either the sun would now rise in the West and set in the East, or East and West would have had to have been defined the other way round.
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The designation of North must have preceded the identification of East and West as orient and occident.
The words orient and occident are two of a set of six French words: orient (east), occident (west), zénith (up), nadir (down), septentrion (north), midi (south) - probably meridian in english.
Why do you think orient and occident predate the others?
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Why do you think orient and occident predate the others?
Not quite what I said.
The designation of North must have preceded the identification of East and West as orient and occident.
It would have been clearer, perhaps, if I had said that it seemed logical, to me, for “North” to have been designated in terms of direction, before “East” and “West” were designated as the directions in which the sun appeared to rise and set, respectively.
Verbosity trumps brevity – or not? :)
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How to decide where is north and south in the maps?
We wouldn't base it on magnetic compass directions.
We know today that the magnetic field of our planet (and our star) can reverse occasionally.
https://en.wikipedia.org/wiki/Geomagnetic_reversal
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I'd say that it was based on a compass heading. Evan mentions the reversal of compass directions but that hasn't happened since the invention of the compass. The last one occurred 41,000 years ago.
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The last one occurred 41,000 years ago.
"My God, this reminds me
Of when we were young"
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I read that the Ptolemy's maps were the first to use math and geometry, and they were used until the early 17th century. But it's all based on his decriptions, because Ptolemy may never have drawn a map himself. Anyway he decribed already a north-oriented, Mediterranean-focused world. Then you can see clearly that in some maps the north is not always up. For example the Tabula Rogeriana (drawn by Muhammad al-Idrisi for Roger II of Sicily in 1154) appears upside-down, probably because the compass began to be used only after 1190. So, I suspect that before the invention of the compass, there was no consensus on where to put the north.
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It would have been clearer, perhaps, if I had said that it seemed logical, to me, for “North” to have been designated in terms of direction, before “East” and “West” were designated as the directions in which the sun appeared to rise and set, respectively
Yes, that’s what I thought you meant.
I was looking at it that first thing early mankind might notice is sun rising and setting - important events so get a name and direction. After a while notice that direction is variable relative to cave/village.
Much later notice stick/tree/standing stone, has shortest shadow in constant direction - wow north, south line
Much later notice stick shadow points to where a star appears, and look it doesn’t move like the rest - wow north star
Dunno, seemed sort of logical to me, how about you Ug?
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Roman maps of the British Isles are remarkably accurate but many are drawn with Scotland on the left rather than at the top of the page.
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How to decide where is north and south in the maps?
If you go "down under, mate", you will find charts where the south is up. You have a northern hemisphere view of things in Australia things are often viewed the other way up.