CrescentReading aspects: what a trine or a square actually does
Five angles, and the difference between ease and friction is less obvious than it sounds.
An aspect is the angle between two planets, measured along the zodiac. Five of them carry most of the meaning, and the geometry is the entire definition.
The five
Conjunction, 0 degrees: the two planets fuse and act as one thing. Neither easy nor hard, just concentrated. Sextile, 60 degrees: a mild opening that requires you to take it. Square, 90 degrees: friction between two functions that keep interrupting each other. Trine, 120 degrees: natural flow, so natural it is often unused. Opposition, 180 degrees: a tug of war that resolves by alternating rather than by winning.
Orb, and why exactness matters
Aspects are not all-or-nothing. An orb is how far from exact the angle is, and a square within one degree is a defining feature of a life while one at seven degrees is background. When people say a chart is intense, they usually mean it has several very tight aspects.
The counterintuitive part
Hard aspects build people. A square forces two functions to negotiate, and the negotiation is where competence comes from. Trines describe talents so easy their owner assumes everyone has them, and therefore never develops them. A chart of nothing but trines is not a lucky chart, it is often an unexercised one.
Applying and separating
If the faster planet is moving toward exactness, the aspect is applying and the matter is still developing. If it has passed, it is separating and describes something already established. Transits work the same way, which is why a transit is usually felt on the way in.
Vedic does this differently
Vedic astrology reads drishti, graha aspects, which are not symmetrical: Mars aspects the 4th, 7th and 8th from itself, Jupiter the 5th, 7th and 9th, Saturn the 3rd, 7th and 10th. Everything aspects the 7th. It is a different geometry answering a different question, and mixing the two vocabularies in one reading is how confusion starts.