Using our solar system’s movement around the Milky Way galaxy as our point of reference, what we consider Earth’s “North” is really the Solar System’s “Front”, and Earth’s “South” is really the Solar System’s “Behind”. Our solar apex (the direction the sun is heading through the galaxy) is currently just southwest of the northern star Vega. So Earth’s northern hemisphere is generally the front seat of our voyage around the Milky Way.

What’s important about this is it means our idea of North isn’t totally arbitrary. The concepts of “above” and “front” are distinct but closely related, far more closely connected to each other than either are to the concepts of “below” or “behind”. If our solar system were actually moving in the direction that our southern hemisphere was facing, then I think it would be fair to say that we’ve got it all completely backwards. In that case we’d be saying what’s “North” or “up” is the opposite direction of where our solar system is moving. Instead, what we’ve collectively decided North is also just happens to be the direction our whole solar system is heading toward. Even if you flipped the galaxy upside down, our solar system would still be moving in the direction we recognize as “North” on our planet. I think that’s significant.

This lends an astronomical basis for the vernal equinox in March to be considered the start of the zodiac, as the northern hemisphere is pointing in the direction the solar system as a whole is facing and moving. Viewing the equinoxes and solstices relative to the galactic plane globalizes the interpretation of the equinoxes so that they equally apply to both hemispheres. Seasonal variations between the hemispheres can add another layer of interpretation to the signs without changing their sects, modes, elements or rulerships. I mean, that’s pretty good news right?

Patrick Watson wrote an interesting article in 2018 where he addresses the tropical zodiac’s hemisphere problem.