AstraLinkGlossary
Combust, under the beams and cazimi: planets near the Sun
In traditional astrology a planet too close to the Sun loses its light in the glare, the way a star vanishes at noon. That is combustion, and it comes in degrees: under the beams, combust, and — at the very centre — cazimi, where the rule flips. Here is what each term means, the exact orbs, and how to read a planet burned or blessed by the Sun.
When a planet sits very close to the Sun it is combust or under the beams, its light lost in the glare and its meaning weakened or hidden. Combust is within about 8.5°, under the beams within about 15°. Exactly conjunct, within 17 arcminutes, it becomes cazimi and is strengthened instead.
What does combust mean in astrology?
Combustion is a traditional way of describing a planet whose light is overwhelmed by the Sun's. A planet is combust when it sits within about 8.5° (8°30') of the Sun — close enough that, in the sky, it is lost in the glare and cannot be seen. Older astrologers, from Ptolemy through Bonatti to William Lilly, treated combustion as one of the weakest conditions a planet can be in: burned up, hidden, unable to act freely, its significations obscured and, in horary, often "afraid" or in the dark.
The image is a visibility metaphor, and it maps onto three zones around the Sun. Further out, from roughly 15° to about 17°, a planet is under the beams — dimmed and partly obscured, but not as afflicted as combustion. Closer than 8.5°, it is combust. And at the very centre, within just 17 arcminutes (17', about a quarter of a degree) of exact, the rule reverses: the planet is cazimi, "in the heart of the Sun", protected and strengthened rather than burned. So distance from the Sun is everything — the same conjunction can weaken a planet or empower it depending on how tight it is.
The orbs at a glance
Orbs vary a little by author, but the traditional scheme most astrologers use is consistent, and it is the one the app applies:
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Combust, under the beams and cazimi
| Condition | Distance from the Sun | Traditional reading |
|---|---|---|
| Cazimi | Within 17' (some use 1°) | In the heart of the Sun: strengthened, clarified, protected |
| Combust | Within about 8.5° (but not cazimi) | Burned: hidden, weakened, hard to see clearly |
| Under the beams | Within about 15° to 17° | Dimmed: partly obscured, less afflicted than combust |
| Free of the Sun | Beyond about 17° | Visible: operating at normal strength |
Orbs differ by tradition; we use 17' for cazimi, 8.5° for combust and roughly 15° to 17° for under the beams, following the medieval sources.
How to find a combust planet
Combustion is easy to check: look at the gap in degrees between the planet and the Sun in the chart. Inside about 8.5° and it is combust; between roughly 8.5° and 17° it is under the beams; inside 17' it is cazimi. Because a chart wheel plots longitude, any calculator or ephemeris will show you the exact separation — the free birth chart reports each planet's degree so you can measure it, and the app's Extended natal reading flags planets that are combust, under the beams or cazimi.
Some planets are combust far more often than others, purely because of orbits. Mercury never strays more than about 28° from the Sun, so it spends a large share of its time under the beams or combust — a combust Mercury is one of the most common placements there is. Venus stays within about 47° of the Sun, so it is combust less constantly than Mercury but still regularly. The outer planets — Mars, Jupiter and Saturn — are only combust for the stretch each year or two when the Sun catches up to them and passes over. Traditional astrology also cares about direction: a planet moving toward the Sun (about to be combust) reads differently from one moving out of the beams into visibility as a morning or evening star, and a retrograde planet approaching a cazimi is a special, closely watched case.
What a combust planet means in a birth chart
Here is where modern practice softens the old verdict, and helpfully so. In a natal chart a combust planet is not "destroyed". Its energy is fused with the Sun — with your core identity, will and sense of self — which has two faces. On one hand its function can be hard to see objectively: so blended with your ego that you may not recognise it as a separate part of you, or may under-value it because it feels like just "who you are". A combust Mercury, for instance, can make someone brilliant but unable to see their own mental blind spots, because thought and identity are welded together.
On the other hand, that same fusion makes the planet intensely personal and single-minded. What is combust is close to the source. Many astrologers now read combustion less as weakness and more as a planet operating privately, from the inside, powerful but not on display — a light you carry rather than shine. The healthiest reading is not fatalist at all: a combust planet asks you to develop objectivity and outer expression for a function that runs deep and unconsciously, so its intensity becomes a strength you can actually use.
As always, which planet, sign and house decide the story, and this is exactly the kind of structural nuance the app's chart reading walks through. A combust Venus asks you to see your own patterns in love clearly rather than assume everyone loves as you do; a combust Mars asks you to own your drive instead of letting it run the show unseen. For the moving sky — when transiting Mercury or Venus goes combust, or reaches the cazimi at the heart of a retrograde — the Cosmic Simulator and the calendar mark the windows, and an early-access reading names any planets sitting in the Sun's glare in your own chart.
Frequently asked questions
What does it mean when a planet is combust?
It means the planet sits within about 8.5 degrees of the Sun, close enough that its light is lost in the Sun's glare and, in the sky, it cannot be seen. Traditionally this weakens the planet: its significations feel hidden, obscured or hard to act on freely. In a natal chart, a combust planet is fused with your identity and will, so its function runs deep and privately but can be hard to see objectively.
What is the difference between combust and under the beams?
Both describe a planet dimmed by closeness to the Sun, but they differ by distance and severity. Under the beams is the wider zone, roughly 15 to 17 degrees from the Sun, where the planet is partly obscured but still functioning. Combust is the tighter zone, within about 8.5 degrees, where the planet is considered burned and much weaker. Under the beams is a shadow; combustion is being lost in the light.
Is a combust planet always bad?
No. Traditional astrology read combustion as a serious weakness, but modern practice is gentler. A combust planet is fused with the Sun, meaning your core identity and will, so its energy is intensely personal and single-minded rather than simply destroyed. The real challenge is objectivity: the function is so blended with your ego that it is hard to see from the outside. Developed consciously, a combust planet can be a quiet strength.
Why is Mercury combust so often?
Because Mercury never travels more than about 28 degrees from the Sun as seen from Earth, it is frequently within the combustion or under-the-beams orb, making a combust Mercury one of the most common placements in astrology. It often describes a mind so merged with personal will and identity that the person thinks decisively but can struggle to see their own biases. Venus, which stays within about 47 degrees of the Sun, is combust less constantly.
What is the difference between combust and cazimi?
They are opposite conditions at different distances from the same conjunction. Combust is within about 8.5 degrees of the Sun and weakens the planet, hiding it in the glare. Cazimi is within just 17 arcminutes of exact and strengthens the planet, placing it in the heart of the Sun. A planet moving toward an exact conjunction passes through combustion, then, for a few hours, reaches the empowered cazimi at the very centre.
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AstraLink content is written by our editorial team, reviewed for astrological accuracy, and refreshed as the sky moves. Interpretations are for reflection and entertainment; they are not medical, legal or financial advice.