Ceres
Ceres was discovered in 1801 as the first body in the asteroid belt, listed at first as a planet, then as an asteroid, and since 2006 has counted as a dwarf planet. That shifting classification is more revealing for astrological interpretation than it at first appears.
The myth
Ceres — Demeter in Greek — is the goddess of grain and of the crops of the field. The familiar part of the story: her daughter Persephone is carried off by Hades. Demeter searches for her, does not find her, and in her grief lets nothing grow any more. Only a settlement ends the famine — Persephone spends part of the year below and part above. Hence the seasons.
It is a story about loss, about grief that brings the world to a standstill, and about a return that is never complete.
The astrological interpretation
Ceres is usually read as nurture in the broadest sense: how someone provides and is provided for, how they deal with separation, what they hold on to and what they let go. She is often tied to the relationship with the mother.
The interpretation is coherent — and it is derived entirely from the name. That is the point at which caution is in order: the body was named after a goddess because it was the first of its kind, and the meaning was drawn from the myth after the fact. Under a different name an equally coherent interpretation would have arisen.
The limits
Ceres rules no sign and has none of the five dignities. Classical astrology is fully staffed with seven planets — every sign has its ruler, every triplicity its lords, every degree its term.
In practice this means: the condition of Ceres cannot be determined. There is no saying whether she is “strong” or “weak”, because there is no yardstick for it. What is left is sign, house and aspects.
A suggestion for handling it
Anyone who wants to work with Ceres should settle beforehand what she is to stand for, and stick to it. The danger with all factors taken up after the fact is the same: they are brought in when the rest of the chart does not yield what was expected — and in that role every one of them is always confirmed.
There are by now hundreds of thousands of named minor bodies. Which of them are interpreted, and why those in particular, is a question every practice has to answer for itself.
See also: Chiron — the same case, a different story — and the planets.