Aspects: How Planets Talk to Each Other
What conjunctions, squares, trines, oppositions, and sextiles mean, why orbs matter more than most guides admit, and how to read the lines on your chart.
The colored chords across the center of your chart are aspects: precise angular relationships between planets, measured along the zodiac. They’re where a chart stops being a list of placements and becomes a system. Planets in aspect don’t act independently anymore.
The five majors
Conjunction (0°). Two planets fused at the same degree, their functions blended into one compound instrument, for better and worse. Venus conjunct Mars is desire and pursuit as one gesture; Saturn conjunct Moon is feeling and discipline permanently in the same room.
Opposition (180°). Two planets facing each other across the wheel, usually across a house axis, which means two life departments pulling on one rope. Oppositions are traditionally read as met in other people first: you find one end of yours in the mirror of relationships. The work the reading proposes is holding both ends instead of outsourcing one.
Square (90°). The friction aspect. Two planets in signs that share a modality but not an element, which is the geometry; the reading laid over it is motion produced by discomfort. Squares get the worst press of the five and the tradition rates them the most productive, which is a judgement rather than a count.
Trine (120°). Same element, and read as flow with a catch: what costs nothing gets taken for granted. The stock example is a Mercury–Jupiter trine, explaining things well without noticing, and therefore never practising it on purpose.
Sextile (60°). Compatible elements, friendly but not automatic. A sextile is an offer: it works when you act on it and idles when you don’t.
Orbs: the part most guides mumble through
An aspect almost never lands exact. The allowance around exactness is the orb, and it is the difference between signal and noise. A square 0.4° from exact is where a reading starts; a square at 6.9° is weather.
On your Undersky chart, aspects are listed tightest-first and the chord lines are drawn heavier the tighter the orb. Read them in that order and stop when you hit the wide ones. We use conventional modern orbs (wider for the Sun and Moon, tighter for everything else) rather than the generous ones some sites use to make every chart look dramatic.
The calculator also lets you choose tight, standard, or traditional orb profiles. Its optional extended layer adds six named minor aspects and keeps declination parallels in their own table, so they never masquerade as the five major longitude aspects described here.
Applying vs. separating: an aspect still closing toward exact (“applying,” marked on your aspect table) is traditionally read as stronger than one already separating. Treat it as a tiebreaker: with two otherwise similar aspects, weight the applying one.
How to actually read one
Take the aspect’s two planets and build a sentence with the aspect as the verb:
- Square → “fights with / forces”
- Trine → “feeds / flows into”
- Conjunction → “is welded to”
- Opposition → “negotiates with”
“My Moon is welded to Saturn” is a different reading from “my Moon feeds Saturn.” Say both out loud and notice which one you want to be true. That’s worth knowing before you decide which one is.
Aspect patterns worth spotting
When three or more aspects interlock, they form named figures: a T-square (two squares to one opposition, a chart’s pressure engine), a grand trine (three trines, a closed loop of ease that can become inertia), a stellium in aspect (one cluster broadcasting to a single receiver). If your chart has one, it’s usually the headline.
Finding and interpreting those figures against your exact orbs is the kind of synthesis the deep reading is built to do.
Part of the Reading Your Chart series. Foundation first: How to read your birth chart.