Astrology (all such systems) stem from Astronomy. Without that basis there is no Astrology that is only the predictive part. Astrology as it stands today along with its Astronomy baggage is almost unchanged from its origins. Its Astronomy package is labeled 'Astrology' by today's Astronomers out of ignorance or impatience to see what it is. I feel it is rather unfortunate. European version of Astrology incorporated the newly discovered planets Herschel (they call it that), Neptune and Pluto.
It only takes that slice of the Celestial Sphere called 'Zodiac' (others call it Ecliptic, but both mean the same not withstanding the redrawing of constellations). So Zodiac is the only subject matter that is the Astronomical basis of Astrology. The time measurements (based on Sun and Moon) are essentially Astronomy, though modern Astronomers don't agree.
The Great Circle of Zodiac is split into 12 signs (same as constellations but redrawn). Sun's transit (time interval) through each of them is called 'Sun' sign; Moon's is called 'Moon' sign.
The line of Zodiac in which Sun moves is like the central verge of a highway. Moon & other planets also move in the path but not on central verge. It is so because as orbit of each is inclined to the (plane of) Zodiac, it deviates from central verge to either side alternatively, crossing the central verge in between at 'nodes'. All move in same direction(East to West) normally. Depending on its position as viewed from Earth, a planet appears to slip back and reverse into a 'retrograde' (West to East) motion for a while till the relative positions are restore as before with normal direction. Inner planets Mercury & Venus move in 'retrograde' direction half of their cycles; as viewed (from Earth) their whole orbit before us - both directions.
One point of contention is the starting point of the circle (girdle) of Zodiac. Zodiac takes Sun in its annual sojourn to the northern most point (nearer to Pole Star) and the farthest on the other (south) after six months; in between Sun crosses (Celestial) Equator going north at Vernal (Spring) Equinox and from north to south at Autumnal Equinox. Equator is the reference with which measurements of planets are taken. Vernal Equinox is reckoned as the start of Zodiac & the Equator too. It is called "the first point of Aries" as that was the constellation there at that point. Precession of the Earth's axis, of the Poles and so for the Equator takes the node sliding down the Equator. This movement, precession of the Poles that takes 26000 years for a full circle is unknown to ancient Astronomers. The position of Vernal Equinox, the starting point of Zodiac at "first point of Aries" stays fixed in Traditional Astrology, even though it is about to enter 'Aquarius', ridiculous as actually the sign Aries is Pisces or Leo happens to be Cancer in reality. It throws all predictions (Astrology) haywire. European Astrology made this amend in line with Modern Astronomy. Indian Astrology is too thick to admit these changes nor to understand it. One Almanac maker, Lahiri amended it. He calls it (the 50"arc/annum) the 'Ayanaamsa' correction. Almanac making is the first book of Indian Astrology that got frozen in time and 'this' tribe is totally Astronomical ignorant, reduced to numerical calculation/computation handed down from a millennium at least.
Astrology is the predictions based on certain perceived traits concocted from the qualities because of the names given to the Astronomical objects. Venus is the most desirable woman in the Western system, but is the teacher/preceptor of King of Demons with wizened visage and flowing silver beard and mane in Indian system. Zeus or Jupiter (Roman name) is the thunder-wielding King of gods in western system while in Indian system he is the sage who advises the king of gods.
If you are interested in 'prediction' post it in Mythology/Folklore.