You know that today, passing of the sun do not match the constellations. The astrology took it's shape in early Mesopotamia, after what Greeks and Romans named the stars and constellations again and again - which knowledge if not for Arabs to keep it, it will be erased through the Middle ages, and since then the constellations change their form, the stars in them moved, and, there is 13 constellations (even then). The one missing is Snake Bearer.
Then, every horoscope sign isn't same. The Virgo is largest on the sky, and Sun needs only week and some to pass through Scorpio.
The interesting thing about the night sky in the south hemisphere is that, first, there is no polar marker. The South cross, it's 2 stars are closest to the astronomical south, but they are far from being static like Polaris here.
The Mayans have recognition of the holes in the Milky way's dust, and they know them as other knows the constellations. In the south, the most significant form in the sky-scape is the Milky way itself, cutting the night in two... there isn't too much constellations there.
The north Polar star, is here only round 14.000 years, and as the Earth wobbles, it will be changed with the star Vega.
Ecliptic is the ring above and below 9 degrees of the Earth's year rotation plane around the sun, and that ring of the Zodiac. Only in this ring the eclipses of the Moon can happen.