Science Forums 2

[Turtle]

Originally Posted by Thunderbird

I think you are forgetting that the poles reverses periodically, so the earth itself has no bottom or top up and down is the direction toward earth.

That refers to the magnetic poles only.* The selection of "up" is arbitrary but a selection is necessary. Horns of a dilemma.

*Here's some info on Earth's 3 types of poles: Planet Earth may have 'tilted' to keep its balance