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Post by CELS on Jul 10, 2004 23:19:44 GMT -5
Hey,
Ever since I've read about distant planets in 40k fiction, where they describe the planet like "the north-west continent" or "the eastern building block", I've been wondering... how do they determine what is north and south, east and west?
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Post by Dazo on Jul 10, 2004 23:47:54 GMT -5
I would think think they take a bearing from terra itself, ships would have left ancient terra knowing which way was up and which way was down so when they arrived at a planet they would have just said, right thats the top so thats going to be north. Well thats my highly technical explanation anyway
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Post by Kage2020 on Jul 11, 2004 1:07:17 GMT -5
Any number of ways, to be fair. If you're lucky enough to have a molten core to your world, then traditional magnetic 'north' could be used. As with Terra, however, this is not necessarily going to be constant... Remembering, of course, that magnetic north has changed a number of times during the 'history' of Earth (last one was around 750,000 ya, if memory serves... 1st year undergraduate course filters hazily up from the depths of the ocean). If not you could use the other tradition... determined north. Choose which one of the poles you want to be your 'north' and then everything is arbitrary. Want to navigate? Find which star is stationary above the pole (or closest to stationary) and use that as your 'north star' or 'east star'. So, 'rational' or arbitrary. The choice is yours...  |
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Post by Tynesh on Jul 11, 2004 5:18:22 GMT -5
On earth, London and Greenwich Meridian are used to determine east and west. This was due to the British Empire having a good deal of clout to be able to establish Greenwich as the centre of time and mapping of the earth. Any line on a planet ma be determined to be 0 degrees, maybe the point where landfall was first achieved or maybe the capital city.  |
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Post by Kage2020 on Jul 11, 2004 5:30:17 GMT -5
Good point... I'd forgotten about those directions automatically falling into the fact that they are a byproduct of the cardinal direction system anyway. Which it isn't exactly... Thanks for the information!  |
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Post by CELS on Jul 11, 2004 7:45:48 GMT -5
Yeah, I know about that, but then I was wondering... you need a north to determine east and west.
Landfall was one of the things I thought of first, but you've still got two poles to choose from. Luckily, most habitable planets seem to have molten cores.
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Post by Tynesh on Jul 15, 2004 23:37:41 GMT -5
Most stars in the galaxy will have systems in the same plane as our own star. Ie. They orbit in a galaxy on the x and y axis of the Milky-way. The poles of the stars will mostly point perpendicular to this plane ie on the z axis.
Assuming that a colony knows where it is in the galaxy and the loction's relation to Terra they will know which pole of the planet points in the same vertical plane as Terra's north pole.
Planets that are tidally locked will 'roll' around their star, hence having no north or south poles but a hot and a cold pole!
There is also the assumption that if the planet had a magnetic field then the N pole of the magnet would point to the corresponding geographic localle.
Cheers Tynesh
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