What the conjunction is
A conjunction occurs when two planets occupy the same degree of the zodiac, at an angular separation of 0°. It is the most powerful of all aspects because it is not a relationship between two separate energies but a fusion: the planets blend into a single, combined force that acts as one.
The conjunction is the seed of every planetary cycle — the moment two bodies meet before separating again into the other aspects.
How the conjunction works
A conjunction intensifies and merges. The two planets can no longer be experienced separately; each colours the other completely. Whether the result is harmonious or difficult depends entirely on the planets: Venus conjunct Jupiter is very different from Mars conjunct Saturn. The conjunction is neutral in itself — a concentration of power that takes its quality from what is concentrated.
By transit and synastry
By transit, a conjunction marks a beginning — a new cycle in the affairs the two planets rule. In synastry (relationship comparison), a conjunction between two people’s planets creates a powerful, magnetic bond in that area of life, for better or worse. Tight conjunctions (small orb) are the strongest features of a chart.