[miguelpais]

But remember also that northern hemisphere navigators like the Portuguese also had to align their maps in a different direction as they crossed the equator and lost their main reference star on their way around Africa.

They soon discovered how to navigate by then aligning with a group of stars called "Cruzeiro do Sul", the Crux constellation[1], which means that it could be reasonable to actually start aligning the maps southwards (and the portuguese were the ones mapping the whole coast of Africa at the time).

But I guess that by that time (around the 1470s), they were already too used to aligning northwards...

[1] http://en.wikipedia.org/wiki/Crux

Edit: I meant northern hemisphere navigators, instead of northern european.

[danmaz74]

If Portugal is in northern Europe, who is then in southern Europe??

[einhverfr]

Roman North Africa? ;-)

[einhverfr]

One of the most interesting beliefs one runs into in the Middle Ages is the idea that although the world is round, it is impossible to travel across the equator by sea or land. This factors into medieval accounts of Alexander the Great for example.

[miguelpais]

Well, the portuguese navigators did have a lot of trouble crossing it. This was due to the fact that they mostly always sailed with the coast in sight, but when they reached the equator, there was just no winds or currents to keep pushing them, so they would just get stuck.

It took them a couple of years to find a way out of that point, by making huge turns westwards into the atlantic (which eventually led them to end up in Brazil, but that's another story...)

[DrStalker]

What did they think prevented this?

[einhverfr]

At least from the medieval literature I have read, it seems like there was a sense that divine retribution would prevent it. I.e. not necessarily about physical barriers but because it was hubris to attempt such a feat.