An attempt to create an astronomy-correct Zodiac information: when every sign (as a constellation) can really be seen, in the sky.
We live on Earth, and (at night) we can see some stars, or even their constellations… The Zodiac – is a group of those constellations, which are seen both good from the Northern and the Southern hemispheres of Earth (at the same moment), – especially – at the astronomical midnight (when the Earth is facing into a direction of the opposite side from the Sun).
Facing the South (if you are on the Northern hemisphere) at astronomical midnight – allows you to see which (of the constellations) is the nearest to the Earth. Using the “Stellarium” application – I can simulate the view onto that parametered sky, see the antisolar point and how it crosses the meridian line of Earth.
The reason why some constellations are seen from both hemispheres simultaneously – is that: they took their space over Earth’s planetary equator.