Luma
A birth chart lists about ten planets spread across signs and houses, as covered in the article on astrological houses. But those planets don’t sit in isolation from each other. They form precise angles between them, and those angles, the aspects, describe how they talk to each other: does your Venus support your Sun, or does it pull in a different direction? The answer rarely comes down to a single chart element, it comes down to how the elements respond to each other.
An aspect is an angle, nothing more mysterious than that
Technically, an aspect is measured in degrees around the zodiac circle. Two planets at the exact same degree form a conjunction (0°). Two planets exactly opposite each other form an opposition (180°). Between those two, other angles come up often enough to each carry their own name and meaning: the square (90°), the trine (120°), the sextile (60°).
This calculation leaves no room for loose interpretation: it follows directly from the planetary positions on the day you were born, down to the minute for the tightest aspects.
The five major aspects
| Aspect | Angle | Nature | What it sets up |
|---|---|---|---|
| Conjunction | 0° | Fusion | The two planets act as a single force, for better or worse |
| Opposition | 180° | Polarity | Tension between two real needs, looking for balance rather than a winner |
| Square | 90° | Friction | An active rub that pushes toward action or adjustment to move forward |
| Trine | 120° | Ease | A natural fluency, sometimes so comfortable it goes unnoticed |
| Sextile | 60° | Opportunity | A potential that needs initiative to become real |
None of these five aspects is good or bad on its own. A trine that’s too comfortable can turn into a talent that never gets trained, for lack of resistance to build it up. A square, on the other hand, wears you down as much as it builds you up: it’s often the most uncomfortable friction in the chart that produces the sturdiest skill, once worked through.
Why orb changes how strong an aspect lands
An aspect almost never sits at the exact theoretical angle. The tolerance around that angle is called the orb: the smaller the gap, the tighter the aspect and the more it shows up in the person’s life; the wider it is, the more the aspect fades into the background. A square that’s 1° off carries far more weight in a chart than one that’s 7° off, even though both technically carry the same name.
When several aspects combine
Some configurations come up often enough to have their own name: the T-square (two planets in opposition, both squaring a third), the grand trine (three planets forming mutual trines, tracing a triangle), the stellium (several planets clustered in the same sign or house). These patterns concentrate the chart’s energy on one specific point, tension for the T-square, fluency for the grand trine.
Spotting these patterns helps identify what actually structures a chart, rather than stopping at the first planet that catches the eye. As with why Luma never predicts anything, these configurations describe a recurring dynamic, not an event on the horizon: a T-square doesn’t predict a dated crisis, it points to a friction point the person keeps running into across very different contexts over a lifetime.
How to spot your own aspects
Looking at your calculated chart, start with the tightest aspects (orb under 2-3°) rather than the full list, which is often long and dense. Then, for each tight aspect, ask what the two planets involved represent on their own before looking at how they combine in you.
That’s the full reading, planet, sign, house, and aspects together, that Luma calculates from your exact birth chart, to help you understand how your own strengths talk to each other, day after day in your journal.