Question Time!

[such_heights]

Calling my geologically inclined friends: please excuse a little lazy-webbing and help me resolve a debate with my father. Is there a non-arbritrary way of distinguishing a planet's north from its south, one that doesn't simply rely on convention? And if not, does that make all sci-fi talk of an unhabitated planet's southern hemisphere etc completely nonsensical?

... These are the things that keep me up at night.

Comments

[elsane]

(hi! I'm mostly offline these days but just happened to log on in time for a question I am professionally qualified to answer, so!). Yes! It makes sense to have north and south poles unambiguously. It's determined by the direction of the planet's rotation. The angular momentum of a planet is a vector directed along its axis of rotation -- north means along the vector, south means against the vector.

Or in other words, sit on the equator facing the sunrise. This unambiguously determines east, and therefore north and south. (:

hope you are doing well, A.

[such_heights]

Hello, you! How's everything going?