Aspects Explained: Conjunction, Square, Trine, Opposition, Sextile

An aspect is the angular distance between two bodies in a birth chart, measured in degrees along the ecliptic. That is the whole definition — it is geometry, not metaphor. Astrologers treat five of those angles as significant, 0°, 60°, 90°, 120° and 180°, because each one divides the 360° circle by a small whole number, and they read a handful of minor angles besides. Everything below is detail: which angles, how far from exact still counts, how much of that is convention rather than measurement, and why the beginner rule that trines are good and squares are bad gets more charts read backwards than any other single idea in astrology.

An aspect is one subtraction

Every body in a chart has an ecliptic longitude: a single number from 0° to 360°, measured along the same circle the twelve signs divide, starting at 0° Aries. To find the aspect between two bodies you subtract one longitude from the other, and if the answer is more than 180° you subtract it from 360°. What is left is a separation somewhere between 0° and 180°. How close that number sits to one of a short list of exact angles is the entire mechanic.

Worked example. Venus at 14° Taurus is at 44° of longitude, because Taurus begins at 30° and 30 + 14 = 44. Mars at 17° Leo is at 137°, because Leo begins at 120°. The difference is 93°. The nearest significant angle is 90°, the square, so this is a square with an orb — a distance from exact — of 3°. No interpretation has happened yet. This is arithmetic anyone can check.

What the arithmetic tells you that the signs do not

• Two bodies in the same sign are not automatically conjunct. A planet at 1° Aries and a planet at 28° Aries share a sign and are 27° apart — no aspect at all under any orb convention in use. That gap is what deflates most claimed stelliums.
• Two bodies in different signs can be conjunct. The Sun at 29° Taurus (59°) and Mercury at 2° Gemini (62°) are 3° apart. That is a tight conjunction across a sign boundary, usually called an out-of-sign or dissociate aspect.
• The same logic breaks the other angles. The Moon at 28° Gemini (88°) and the Sun at 2° Libra (182°) are 94° apart — a square by degree, even though Gemini and Libra are four signs apart and would be a trine if you counted signs instead of degrees.

Why only certain angles are read

The five classical aspects are not an arbitrary shortlist. Each is the circle divided by a small whole number: 360 ÷ 1 gives the conjunction, ÷ 2 the opposition, ÷ 3 the trine, ÷ 4 the square, ÷ 6 the sextile. That is the organising idea, and it is why the set stops where it does.

There is a second reason those five and not others. All five land on exact multiples of 30°, so each also describes a clean relationship between whole signs — a trine is always four signs along, a square always three. Traditional astrology read aspects as relationships between signs rather than between degrees, so an angle falling between sign boundaries had nowhere to live. 360 ÷ 5 is 72°, which sits two-fifths of the way through the third sign and belongs to no sign relationship at all. That is the structural reason the quintile was not part of the classical set and only entered the literature with Kepler in 1619.

Landing on a multiple of 30° was necessary but not sufficient, and the modern lists quietly dropped the second half of Ptolemy's rule. He derives the configurations from simple fractions of the circle — a half, a third, a quarter, a sixth — and then says explicitly that signs standing 30° or 150° apart are disjunct: they share no polarity and no connecting figure, so he reads nothing between them at all. The semisextile and quincunx below are later additions that reopened exactly the pairs he had closed, which is a large part of why both are read with such tight orbs.

The fourth column is where the argument becomes visible: every classical angle resolves to a clean statement about signs, while every minor one either falls between sign boundaries or lands on a pair the tradition read as unrelated.

The five classical aspects, one at a time

What follows is the traditional reading of each angle. It describes a long-standing interpretive convention; it is not a claim about what happens to anyone.

Conjunction — 0°, the circle undivided

Two bodies at the same degree. They do not cooperate, they merge: whatever each one does tends to happen through the other, and neither is easy to observe on its own. This is why the conjunction is the only classical aspect with no inherent character — Sun conjunct Jupiter and Mars conjunct Saturn read very differently, and the difference is entirely in the bodies, not the angle. It carries the widest allowance of the five in most conventions. Longer treatment at what is a conjunction.

Opposition — 180°, the circle halved

Bodies at opposite points of the wheel. When it is not out of sign, an opposition always joins two signs of the same modality in complementary elements — Aries and Libra pair cardinal fire with cardinal air, Cancer and Capricorn pair cardinal water with cardinal earth. The two ends share a tempo and are not temperamentally hostile; what they are is at maximum distance, pulling opposite ways on one axis. The traditional reading is not a wall but a see-saw: distance is what makes a thing visible, and this is the one hard angle whose two ends are in plain sight of each other.

Trine — 120°, the circle in thirds

Bodies four signs apart, always in the same element — fire with fire, water with water. The two want compatible things, so the pairing runs without resistance. The old textbooks call it a benefic aspect and they are describing something real: a trine between Venus and Jupiter hums. What ease costs is the subject of the next section. More at what a trine is.

Square — 90°, the circle in quarters

Bodies three signs apart, in the same modality but in elements that do not mix — cardinal fire against cardinal water, and so on. Same tempo, incompatible aims. A square between Mars and Saturn grinds, and in the tradition the grinding is the point: the two ends cannot ignore each other and cannot proceed unchanged. This is also the aspect beginners most reliably misread. Longer treatment at what a square aspect is.

Sextile — 60°, the circle in sixths

Bodies two signs apart, in elements traditionally read as compatible: fire with air, earth with water. It is the trine's quieter relative — cooperation that is available but does not assert itself, and the usual formulation is that a sextile has to be taken up rather than simply enjoyed. It carries the tightest orb of the five, and it is the first aspect most astrologers drop when they want a shorter list.

Trines are not rewards and squares are not punishments

The most common beginner error is to sort aspects into good and bad — trines and sextiles in one column, squares and oppositions in the other — and read the chart as a scorecard. The vocabulary invites it. Hellenistic astrology sorted the planets into benefics and malefics; the labels travelled through the medieval and Renaissance literature into English, and by the nineteenth-century revival they were being applied to the aspects as freely as to the planets. Extending a classification of bodies to a classification of angles is where the scorecard reading comes from, and it produces bad readings.

Take the two halves separately. A square is two bodies moving at the same tempo toward aims that do not fit together. The tradition reads that friction as the thing in a chart most likely to prompt action, on the plain grounds that a mismatch which cannot be ignored is a standing invitation to do something about it. That is a description of how the convention works, not a promise about anybody's life.

A trine is the reverse case: two bodies that want compatible things generate no prompt at all. The traditional observation is that what comes easily tends to get used rather than examined. It is why experienced astrologers describe grand trines — three bodies each 120° from the next — as closed rather than lucky: a self-sufficient loop with nothing pressing on it.

The useful reframe is that hard aspects describe where energy is spent and soft aspects describe where it flows without being spent. Neither is better, and there is no such thing as a better chart. A page that told you otherwise would be scoring people, which is not what this is for.

How many aspects will you find? Do the arithmetic first

This is worth computing before you go looking, because it explains why long aspect lists say so little. Ten bodies — the Sun, the Moon and the eight planets from Mercury to Pluto — make 45 distinct pairs. Every pair has a separation somewhere in the 0°–180° range, and every aspect claims a slice of that range: twice its orb for an angle in the middle, once its orb for one at either end, since a separation cannot run past 0° or 180°.

Take one ordinary orb set and add the slices: 8° for the conjunction, 8° for the opposition, 7° for the trine, 7° for the square, 5° for the sextile. The conjunction and opposition each claim 8° of the range because they sit at its ends; the trine and square claim 14° each and the sextile 10°. That is 54° out of 180, or 30 percent. Spread evenly, you would expect a major aspect on about 13 or 14 of the 45 pairs.

Now switch on the six minor aspects at 2° apiece. Each sits in the middle of the range, so each adds 4°: another 24°, taking the total to 78° of 180, or 43 percent. You would now expect an aspect on roughly 19 or 20 of the 45 pairs — and a chart where two pairings in five are aspected is a chart where being aspected carries almost no information.

That estimate assumes separations are uniformly distributed, which real charts are not: Mercury never appears more than about 28° from the Sun and Venus never more than about 48°, so those pairs are permanently locked into a narrow band of possible aspects. The direction of the conclusion holds anyway. Widening orbs and adding minor aspects does not find you more truth, it finds you more entries. Tighten instead.

Orbs: the part of an aspect list that is a settings choice

An orb is the tolerance around an exact angle. Exact aspects, to the arcsecond, essentially never occur in a real chart, so every aspect you have ever been told about was inside somebody's orb allowance.

The rule everyone agrees on is that tighter is stronger. A square 0°20' from exact is a defining structural feature of a chart; the same square at 6°30' is background texture, and many astrologers would not list it at all. If you read only one number next to an aspect, read the orb.

The rule nobody agrees on is how wide the allowance should be. There is no experiment behind an 8° conjunction orb. It is inherited practice, and it varies: textbooks differ, astrologers differ, and chart software ships different defaults. Two competent astrologers can produce two different aspect lists for the same birth data and both be working correctly. Any aspect list is therefore partly a settings choice, which is why the honest question when someone tells you your chart has a certain aspect is: at what orb?

Where two bodies with different allowances meet, one common method is to average the two — the moiety approach — rather than take the wider of the pair. Again, a convention, and one Zodiux does not implement: its orbs are set per aspect and applied identically to every pair.

One more distinction worth knowing. An aspect is applying when the faster body is still moving toward exact, and separating when it has passed it. Traditional practice reads applying aspects as the stronger of the two. Deciding which is which needs each body's daily motion, not just its position, and a retrograde body reverses the answer — see what retrograde means.

How to find your own tightest aspects by hand

Zodiux runs this arithmetic for you in the browser, so nobody has to do it to use the chart. Do it once anyway. It is what makes any aspect list legible, it is the only way to work a chart computed somewhere else that publishes degrees but no aspects, and it is how you check a list you were simply handed. It needs nothing but subtraction.

Eight steps, in order

1. Write each body's position as an absolute longitude. Number the signs from Aries = 0 to Pisces = 11, multiply by 30, add the degrees within the sign. Sagittarius is index 8, so 12° Sagittarius is 8 × 30 + 12 = 252°.
2. Pick a pair and subtract the smaller longitude from the larger. If the result is more than 180°, subtract it from 360°. You now have a separation between 0° and 180°.
3. Compare that separation with the five classical angles: 0°, 60°, 90°, 120°, 180°. Take the nearest one.
4. Subtract to get the orb. A separation of 116° against a 120° trine is a trine with a 4° orb.
5. Decide whether to keep it. Use the table above: allow the tighter of the two bodies' allowances, or average them, and be consistent across the whole chart rather than generous where you like the result.
6. Repeat for every pair. Ten bodies is 45 pairs, which is a tedious half hour by hand — but doing ten pairs manually once is what makes the rest legible.
7. Sort the survivors by orb, ascending. The tightest three or four are the aspects that characterise the chart; everything past about 5° is context.
8. Re-run the list with a hard 3° ceiling and no minor aspects. What survives that cut is the durable core, and it is usually a much shorter and much more interesting list than the default output of any chart app.

Tightness is a ranking, not a verdict, and it needs one correction before you read the top of the list: check whether both bodies are slow. Two outer planets can sit inside a 1° orb for years, which makes that aspect the least personal thing in the chart despite being the tightest. How to read a birth chart works a real example of exactly that trap.

One input limits the whole exercise. The Moon's daily motion, measured across 2026 with this site's ephemeris, ranges from 11.79° to 15.30°, so a birth time uncertain by two hours puts its longitude in doubt by more than a degree — enough to make or break a tight aspect, and enough that a rounded time should make you distrust the bottom of any lunar list before you distrust the method.

What the Zodiux chart computes, and what it leaves out

The free chart does compute aspects, and it does it in your browser. It takes all 45 pairs among the ten bodies, folds each separation into the 0°–180° range exactly as described above, and keeps any pair that falls inside its orb for one of the five classical angles. Every surviving aspect is drawn as a line across the wheel — hard angles (square, opposition) in red, conjunction, sextile and trine in the cool accent — and the eight tightest are printed underneath as a list, sorted by orb, smallest first. The placement list gives each body's sign, its whole degree inside that sign, and a retrograde marker; the wheel itself is rotated so the Ascendant sits at the left, or 0° Aries if no birth time was given.

The orbs are fixed and flat: conjunction 7°, sextile 5°, square 6°, trine 7°, opposition 7°, applied identically to every pair. There is no per-body allowance and no moiety averaging, which is a deliberate simplification with a real cost — a Neptune–Pluto conjunction is allowed the same 7° as a Sun–Moon one, so a slow-planet pair shared by a whole birth cohort can outrank a genuinely personal contact at the top of the list. That is the single most useful thing to know before reading the output, and the reason step seven above ends with a caveat rather than a ranking.

Four things are deliberately absent. No minor aspects — the six angles in the table above are not computed at all. No house cusps, because Zodiux takes no position on Placidus versus Whole Sign versus Koch and would rather say so than pick one silently. No aspects to the Ascendant or Midheaven, because those depend on the birth minute and a rounded time would contaminate the whole list rather than just one entry. And no bodies beyond the ten: no Chiron, no asteroids, no lunar nodes.

With no birth time, the chart is computed for local noon in the birth city. The planetary aspects still stand up — the Sun and the slow bodies barely move in half a day — but the Moon's longitude can be off by up to about 7°, wider than any orb on this page, so no lunar aspect from a timeless chart means much. The rising sign is omitted rather than guessed, which is also why no aspect to it appears. None of this reaches a server: the arithmetic runs in the page, and the birth details stay out of the address bar unless you press Copy link, which puts them in a URL fragment that browsers never transmit — see saved charts and privacy.

The same ephemeris drives the other surfaces here. The live sky prints every body's current sign, degree and retrograde status, which is what you need to work a transit against a natal degree; transits and retrogrades covers that method and carries the retrograde frequency table this page deliberately does not repeat.