The five aspects

Why these five

They divide the circle by one, two, three, four and six — a point, a line, a triangle, a square and a hexagon. Ptolemy described the four angles in the second century, and later astrologers grouped the conjunction with them, which is why all five are often called Ptolemaic. Each joins signs with something in common or something in conflict: a trine joins signs of the same element, a square signs of the same modality and different elements, an opposition signs of the same modality and complementary elements, a sextile signs of friendly elements. The meanings grew out of that geometry rather than being laid on top of it.

Other angles exist — the semi-sextile at 30°, the semi-square at 45°, the quincunx at 150° — and many astrologers use them. The chart here draws only the five, to keep the wheel readable; the 150° angle appears only as part of the yod on the aspect patterns page.

How close counts

An aspect is rarely exact, and how far from exact still counts is a convention rather than a measurement. These are the orbs this site uses, the same numbers the chart applies:

• Conjunction: within 8° between planets, 10° with the Sun or Moon, 8° between two charts
• Sextile: within 5° between planets, 6° with the Sun or Moon, 4° between two charts
• Square: within 7° between planets, 9° with the Sun or Moon, 6° between two charts
• Trine: within 7° between planets, 9° with the Sun or Moon, 6° between two charts
• Opposition: within 8° between planets, 10° with the Sun or Moon, 8° between two charts

While the faster of two planets is still moving towards the exact angle the aspect is applying, and once it has passed it the aspect is separating. The tradition reads an applying aspect as building and a separating one as easing off. Aspects are counted by degree, not by sign, so 29° Aries and 2° Cancer make a sextile even though those signs are square; such out-of-sign aspects count, but are read as less typical.

Working out an aspect by hand

Every position in a chart can be written as a number from 0° to 360°, counted from the start of Aries. Each sign adds 30°, so 14° Leo is 134° and 20° Scorpio is 230°. Subtract one position from the other, and if the answer is more than 180°, take it from 360°, because the shorter way round the circle is the one that counts. Then see whether the result lies within orb of 0°, 60°, 90°, 120° or 180°.

The Sun at 14° Leo and the Moon at 20° Scorpio are 96° apart: 6° past a square, and inside the wider orb a square gets when the Sun or Moon is one of the pair. Mars at 2° Aries and Saturn at 27° Scorpio give 235°, which becomes 125°, a trine 5° wide. Jupiter at 10° Gemini and Venus at 25° Cancer are 45° apart and make none of the five. The chart does this for every pair, forty-five pairs among the ten planets alone, and draws a line for each one that qualifies.

Signs that make no aspect

Counted in signs, the five angles are 0, 2, 3, 4 and 6 signs apart. That leaves two gaps: neighbouring signs, one apart, and signs five apart, such as Aries and Virgo or Aries and Scorpio. Neither distance is one of the five, and the older tradition said such signs cannot see each other, calling them averse. Neighbours share neither an element nor a modality, and nor do signs five apart, which is the geometry behind the name.

Early astrologers also counted aspects from sign to sign, so that any planet in Leo was square to any planet in Scorpio. Measuring by degree with an orb came later, and this site follows it. The two views meet in the out-of-sign aspect, where the degrees say one thing and the signs another.

How often the sky makes them

The Moon gains about 12° a day on the Sun, so in the 29.5 days from one new Moon to the next it makes every one of the five. The conjunction is the new Moon itself. A sextile follows about five days later, the square at first quarter, a trine near day ten and the opposition at the full Moon, and then the trine, square and sextile come again on the way back. The Moon page follows that month day by day.

Two planets of any speed run through the same eight steps between one meeting and the next; only the timescale changes. Jupiter and Saturn take about twenty years over it, which is why a slow aspect is shared by everyone born within months of each other, while an aspect of the Moon is over within a day or so. It is also why the time of birth matters most for the Moon’s aspects and hardly at all for those between the slow planets.

Where aspects are read

In a birth chart the aspects are the lines across the middle of the wheel. Between two people’s charts they are the substance of compatibility; between the moving sky and a birth chart they are transits; and when several join up they make the grand trines, T-squares and yods of the patterns page.

Easy and hard are the tradition’s words, not verdicts: a trine is not lucky and a square is not bad. Nothing on these pages predicts what an aspect will bring.