Opposition — 180°, voiced as a octave.
The opposition carries a harmonic ratio of 2:1. Applied to Mercury and Venus, the pair holding the angle now, it sounds at 116.0 Hz against 121.0 Hz.
Stereo headphones for the beat.
The carrier is the geometric mean of the two bodies' base frequencies with the aspect's ratio applied — √(f₁ × f₂ × 2) — then folded by octaves into the 110–440 Hz band. Octave equivalence is the only transformation in the chain: doubling preserves every ratio in the set, so the fold moves the register and leaves the relationship untouched. No tempering, no transposition, no key.
The right channel runs 5 Hz above the left. The beat is the output, not the tone; through speakers the two collapse into one centred pulse and no binaural claim is made for that.
At 2:1 the opposition is the only angle in the set carrying the octave. The harmonic holds whether or not the pair is inside the 2° orb — it is a property of two bodies and an angle, not of a moment. Which aspects are actually live is a separate question, and the ranked table answers it.
The six intervals
- Semi-Sextile — 30°minor third
- Sextile — 60°perfect fifth
- Square — 90°perfect fourth
- Trine — 120°perfect fifth
- Quincunx — 150°major sixth
- Opposition — 180°octave
Frequencies are the instrument's own and are stated as fact because you can press play and check them. Horoscorpio states angles, intervals and times; it makes no therapeutic claim and no claim about what an angle causes.