The conjunction is the meeting: two planets on the same degree of the zodiac, or a few degrees apart. There is no angle between them, the distance is zero, and that is why it is the only aspect with no "side".

An aspect is the distance between two planets measured on the wheel of the zodiac. When that distance falls close to an angle the tradition recognises, the two are said to form an aspect, and that is what links one part of the chart to another. The whole logic is in what an aspect is.

I measured 200,000 charts drawn at random between 1930 and 2025, with the same orbs this site uses to cast charts and with the engine’s own rule: each pair of planets forms one one aspect, the tightest one.

The square (90°) appears 2.90 times per chart on average, is in 93.5% of charts and accounts for 23.4% of the five major aspects; the sextile (60°), 2.82 times, in 94.1% of charts and with 22.8%; the trine (120°), 2.68 times, in 92.9% and with 21.6%; the conjunction (0°), 2.47 times, in 93.9% and with 19.9%; the opposition (180°), 1.52 times, in 73.0% and with 12.3%; and the quincunx (150°), which stays out of the count of the five major ones, 0.93 times, in 58.2% of charts.

The conjunction takes up a single place on the wheel and still reaches 19.9% of the major aspects, against the 12.3% of the opposition, which also takes up a single place. What lifts it is the orb: the conjunction has the widest of all, ten degrees when both are the Sun or the Moon, tied with the opposition. And there is a second reason, which belongs to the inner planets: Mercury never gets more than 27.8° from the Sun and Venus never passes 47.2°, so those two pairs live close, and close, for a conjunction, means forming one.

And there is a number this measurement shows that almost no astrology text says out loud: 93.9% of charts have at least one conjunction. Having one distinguishes almost nobody. What distinguishes is WHICH planets it links, and which houses they are in.

The conjunction joins, it does not blend. The two planets start acting as one thing, and whoever has them can hardly ever tell one from the other, someone with Venus and Saturn together does not feel "affection" and "limit" in two beats: they feel one thing that is both at once, and assume everyone feels the same.

The limit is worth saying: these are tendencies, not a verdict. An aspect describes how two functions of the chart talk to each other, it does not foretell events, diagnoses nobody and decides nothing for you.

The aspect on its own says almost nothing: what gives it a subject are the two planets. These four pairs are among the most common, and they show how the same geometry changes face:

• Sun–Moon: whoever is born at the New Moon has will and need pulling in the same direction, which is comfortable and also blind.
• Moon–Saturn: emotion comes out with a factory-fitted brake, and it tends to show up in someone who doesn't ask.
• Venus–Mars: taste and the drive to go after it are the same thing, and desire comes without hesitation.
• Sun–Pluto: identity comes with built-in intensity, and there is no discreet presence possible.

Notice that the angle is the same in all four and the subject is completely different. That is why "I have a conjunction" is not a reading, it is the start of one.

Neptune and Pluto have not met for more than a century. They spent the last hundred years between 42.6° and 65.3° apart, locked in a resonance that keeps them in that band, the only thing they form is the sextile. A conjunction between the two is a five-hundred-year event, and it has not happened in the chart of anyone alive.

This is not a rule of one school: it is the orbits of the planets. And it is a useful check at home, if a site shows one of those pairs with this aspect, it is not calculating the sky.

Two planets almost never fall on the exact angle. The orb is the leeway allowed: how far off the angle the aspect can be and still count. And it does not belong to the aspect alone, it depends on who forms it.

This site uses a wider orb for the Sun and the Moon, a narrower one for the outer planets, and takes the average of the two. Measured across the same 200,000 charts: when a conjunction happens, the average distance to the exact angle is 3.92°. That is, the tight aspect is far more common than the one on the edge, and your chart shows the exact distance of each, instead of only the name.

The question that matters is not how many you have: it is where they fall. An aspect between two planets in the 10th house speaks of work and reputation; the same aspect between the same planets in the 4th speaks of home and family. The house depends on the hour and city of birth, and it is what turns geometry into a reading.

The two texts that carry on from here are what an astrological house is, which explains the twelve areas, and what the birth chart is, which puts the whole picture together.

And the questions that come up most on this subject, with the short answer: