What is the difference between combustion and the acronychal phase?

Combustion means the planet's elongation from the Sun has fallen below its own visibility threshold, so it is lost in the glare. The acronychal phase means the elongation exceeds 170°, putting the planet opposite the Sun and visible all night. One is total concealment and the other total display; they are not two ends of the same passage.

How long does combustion or an acronychal phase last?

It is measured from the planet's actual entry into and exit from the state, and the reading window can extend to a maximum of 1,100 days. Slower planets hold both states longer, so check the specific start and end dates.

Is this the same as heliacal rising and setting?

No. A heliacal rise or set is the moment a planet crosses the boundary of visibility. This entry judges the state the planet is already in, either combust or acronychal, and a planet that is merely visible produces no entry at all.

Combustion & Acronychal Phase

Your chart · time-limitedSteady♄︎Classical AstrologySelf

This matter is either fully out in the open or entirely under wraps, with nothing in between. Sort out which one applies before acting on related plans or messages: push ahead on what is clearly visible, and park what is not rather than guessing.

In detail

This entry judges two states only and says nothing about the range between them. A planet is combust when its elongation from the Sun falls below its own arcus visionis, meaning it is lost in solar glare and invisible to the eye; the thresholds for the five classical planets are Mercury 13°, Venus 5°, Mars 17°, Jupiter 11°, and Saturn 15°. A planet is acronychal when its elongation exceeds 170°, standing opposite the Sun and visible for the whole night. The two are not the rising and setting ends of one passage but the two extremes of concealment and full display; a planet that is merely visible produces no entry. Mercury and Venus never reach 170° of elongation, so they can only ever be combust. Classical judgment treats visibility as a planet's capacity to act openly, so combustion reads as suppression and withdrawal, and the acronychal phase as full manifestation.

FAQ

What is the difference between combustion and the acronychal phase?: Combustion means the planet's elongation from the Sun has fallen below its own visibility threshold, so it is lost in the glare. The acronychal phase means the elongation exceeds 170°, putting the planet opposite the Sun and visible all night. One is total concealment and the other total display; they are not two ends of the same passage.
How long does combustion or an acronychal phase last?: It is measured from the planet's actual entry into and exit from the state, and the reading window can extend to a maximum of 1,100 days. Slower planets hold both states longer, so check the specific start and end dates.
Is this the same as heliacal rising and setting?: No. A heliacal rise or set is the moment a planet crosses the boundary of visibility. This entry judges the state the planet is already in, either combust or acronychal, and a planet that is merely visible produces no entry at all.

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