Zodiac tuning fork — 172.06 Hz

172.06 Hz is the tone of precession, the slow wobble of the Earth's axis that takes about 25 920 years to complete one full circle. This cycle is called the “Platonic Year”, and the fork is called “Zodiac” because over that time the point of the spring equinox travels all the way around the zodiac.

Frequency (middle octave)	172.06 Hz
Note	F · −26 cents from standard tuning A = 440 Hz
Tuning in which this is an exact note	A = 433.55 Hz
Cycle	precession of Earth's axis, the “Platonic Year”25 920 years
Doublings from the cycle's frequency	47
Color (the same frequency as light)	violet · 396 nm
Paint on the Acutonics tuning fork	blue-violetshade measured from photos in the school's catalog — this is NOT the computed colorcolor name “Purple” — school page · Acutonics Canada
What can be checked	Reproducible

It is the longest cycle in the set, and it needs the most doublings: forty-seven. Yet the frequency it produces is just as ordinary as all the others, because the law of the octave does not care where a period came from.

Tradition assigns this tone to the crown chakra and to questions of destiny, things larger than a single life. The logic is symbolic and quite transparent: the slowest of the cycles is linked to the most “transpersonal” of the levels.

⚠ Watch out for a neighboring number: Chiron is 172.86 Hz. The difference is less than one hertz, almost impossible to tell apart by ear, and easy to mix up in a table.

How this number is obtained

The axis is logarithmic: each doubling raises the sound by exactly one octave. The pitch goes up, the note stays the same.

Given: the period of the Platonic Year (Zodiac)

25 920 years = 817 972 992 000 seconds

1The frequency of the cycle itself: how many times it repeats per second

1 ÷ 817 972 992 000 = 0.000 000 000 001 222 5the same in short form: 1.22 × 10⁻¹² Hz

A tiny number that cannot be heard: human hearing starts at about 20 Hz. But it is a real frequency, and we can keep working with it.

2Raising it into the audible range: each doubling is one octave up

0.000 000 000 001 222 5 × 2 = 0.000 000 000 002 445 11st doubling

0.000 000 000 002 445 1 × 2 = 0.000 000 000 004 890 12nd doubling

0.000 000 000 004 890 1 × 2 = 0.000 000 000 009 780 33rd doubling

⋮43 more doublings just like these

86.03 × 2 = 172.0647th doubling: now it is in the middle fork band

Or, in a single line:

0.000 000 000 001 222 5 × 2⁴⁷ = 172.06 Hz

where 2⁴⁷ = 140 737 488 355 328, the number of times the frequency has grown

The value Cousto published is 172.06 Hz. It matches.

3Which note it is

12 × log₂(172.06 ÷ 440) = −16.26semitones from A

nearest whole number: −16 = Fand that is the note

remainder: −0.26 of a semitone = −26 centshow far the tone is from the note

One hundred cents make one semitone. Planetary frequencies almost never land exactly on a note: orbits know nothing about musical tuning.

4In which tuning it would be an exact note

172.06 ÷ 2^(−16 ÷ 12) = 433.55 Hz

An ordinary piano is tuned to A = 440 Hz. Here the tone gets a tuning of its own, and for the Om tone it is exactly the much-discussed 432 Hz.

5Color: the same frequency raised all the way to light

172.06 × 2⁴² = 756 712 050 026 574 Hzthat is 7.57 × 10¹⁴ Hz, already visible light

299 792 458 ÷ 756 712 050 026 574 = 396 nmwavelength → violet

Divide the speed of light by the frequency and you get the wavelength. This is a model, not the measured color of a planet, but the arithmetic is exactly the same as for sound.

Octave ladder

Octave	Frequency	How it is used
2^44	21.51 Hz	below or at the edge of hearing
2^45	43.01 Hz	below or at the edge of hearing
2^46	86.03 Hz	low: stronger vibration on the body
2^47	172.06 Hz	the main tuning fork
2^48	344.11 Hz	high: work in the field above the body
2^49	688.23 Hz	high: work in the field above the body

What tradition ascribes

Tradition

The crown, meaning, the direction of a life. A meditative tone.

This is a system of correspondences, not the result of a measurement: controlled studies of planetary frequencies do not exist. We present the tradition because it exists and the practice is built on it — but we call it tradition.

Intervals with this tone

Interval	Pair	Ratio	Difference
Zodiac 3	Om + Zodiac	1.264	35.96 Hz

All frequencies in one chart · how the calculation works · what has been proven