What determines which way 'up' the planet Earth is?

Question

This doesn't just apply to Earth, but all planets... Today in society we accept that the North Pole is at the top and the South Pole is at the bottom. How do we know which way is up? If you turn an atlas upside down, you might think "that's wrong..." but... is it?

For argument's sake, is Australia near the top of the world? Is it 'above' or 'below' the equator?

At a guess, I'd say the first people to sail round the world and draw a map (probably us Brits) decided that they wanted their country to be in the 'top' half of the world. But I can see no merit in being in the 'top' or the 'bottom'.

Answer 1

Most of the world's land mass as well as most of the world's population (including most of the influential empires leading into the modern era) is in the northern hemisphere, so putting this hemisphere at the top of the map was a natural historical development.

Answer 2

Hah, yes I have wondered the same thing about why the top is the top.

I would imagine that rotation determines some of it. Then North and South poles determines the rest.

Answer 3

u know.. tht makes sense... i mean.. who knows.. maybe south is really the top.. no one can tell... actually..

Answer 4

Except for the magnetic and rotational poles, there is no correct orientation. A map is just as accurate if north is at the top as if south or west is at the top.

Answer 5

I could be wrong, but I'm guessing when the first compasses were developed, they didn't REALLY know what made the needle always point north, but it did, so they started with that direction at the top when they came up with north, south, east, and west.  Of course, if you were actually standing on the moon looking at the Earth, the north pole would be the top of the world from your point of view.  That's actually a pretty good question...

Answer 6

well, if by up you mean north, and then down is south, the magnetic poles of the earth determine this.

But, every 11 years or so, the poles change, making south to north, and north to south. So... thats about it. Its just the magnestic poles.

Answer 7

What determines 'up' and 'down' on Earth is gravity; the direction towards the center of the Earth is down and the opposite direction is up.

In astronomy however or looking at the planet as a whole up and down has no meaning; maybe they can be used but the definition then it's just a matter of convenience; most probably because more people live on the northern hemisphere: North is up and South is down. But then again north and south are by defined by convention themselves as well.