When two planets form an aspect in astrology, they rarely do so at exactly the precise angle. A trine is 120 degrees, but two planets at 118 degrees are still considered trine. The amount of allowable deviation is called the orb.

Orbs might seem like a technical detail, but they significantly affect which aspects you consider active in a chart and how strongly you weight them. Understanding them well makes your chart readings more accurate.

Why orbs matter

The closer an aspect is to exact, the more strongly it tends to manifest in a person's life. A Sun-Saturn conjunction at one degree of orb is tighter and often more pronounced than a Sun-Saturn conjunction at seven degrees. Both are active. Both carry the same essential meaning. But the tighter aspect tends to be more intensely felt.

If you use very wide orbs, you will find aspects everywhere and the chart becomes noise. If you use very tight orbs, you may miss real connections. The art is calibrating appropriately.

Standard orbs by aspect

Most western astrologers use orbs in this general range, though preferences vary:

Conjunction and opposition: up to eight or ten degrees, with tighter orbs considered more significant. Some astrologers allow up to twelve degrees when the Sun or Moon is involved.

Square and trine: up to six or eight degrees.

Sextile: up to four or six degrees.

Minor aspects like the quincunx or semisquare: two to three degrees at most. The more obscure the aspect, the tighter the required orb to take it seriously.

Applying versus separating

An aspect is applying when the faster-moving planet is moving toward the exact angle. It is separating when the faster planet has already passed the exact angle and is moving away. Applying aspects are generally considered slightly stronger, because the energy is building toward maximum intensity. Separating aspects describe energy that has already peaked, more settled and integrated.

In synastry and compatibility work, applying aspects between charts carry more forward momentum.

The Sun and Moon get wider orbs

Most astrologers give the Sun and Moon wider orbs than other planets, often allowing up to ten degrees for aspects involving either of them. This reflects the Sun and Moon's particular importance in the chart.

Practical advice on orbs

When reading your own chart, start with the tightest aspects, those within two or three degrees. These are almost always where the most significant chart themes live. Then broaden out to the five to six degree range for trines and squares, and use your judgment about whether looser aspects feel relevant in context.

A chart with no aspects inside three degrees and many aspects in the seven to eight degree range is going to feel more diffuse than one with several tight aspects. The tightness of a chart's aspects partly determines how concentrated or distributed the person's energies tend to be.