Akrav (Scorpio) is the Southernmost constellation of the Zodiac. As such, it is always south of the ecliptic. To understand this better I will give a bit of background on the constellations of the Zodiac.

There are an unlimited number of constellations among the stars. What is unique about the Zodiac constellations is the fact that they lie in the plane of the ecliptic, that is, the plane in which the planets rotate around the sun. Therefore, the moon and planets and even the sun itself will always be seen along the backdrop of the same groups of stars. These stars are divided into twelve groups, or zodiac constellations, one for each month of the sun's "revolution around the earth" (from our perspective). Every year, the sun will be seen against the same stars at the same time of year.

The ecliptic is not exactly parallel to the equator - since the earth's pole is inclined 23.5 degrees to the plane of its orbit around the sun. Thus, the ecliptic rises above (north) of the equator 23.5 degrees and dips 23.5 degrees below it (south). The constellation at the most southerly part of the ecliptic is Scorpio. This is what Chazal mean when they say "Akrav is in the south." It doesn't mean that Akrav is the "South Star." (In the northern hemisphere, there is no stationary south star, like there is a north star. Even in the southern hemisphere, there is no star at the stationary point around which the southern heavens rotate; there is a nearby constellation called Crux.)

I hope that makes things clearer.

Best wishes,

Mordecai Kornfeld