Frequency Atlas

Moon Culmination Period (Cosmic Octave)

187.61 Hz

Nearest note: F♯3, 24 cents above standard tuning

A tone calculated from a measured cycle, by doubling its frequency 24 times. It is calculated, not recorded.

How well is this supported?

DerivedOctave of an astronomical cycle

Calculated from a measured value by a stated method. You can check the arithmetic. What the result means is a matter of interpretation.

The cycle is measured. The tone is calculated from it by doubling, so that it can be heard. Nothing in space makes this sound.

What the four labels meanChecked against sources September 27, 2026

The button plays a plain tone. Start with the volume low. Phone and laptop speakers play low notes quietly; headphones or a speaker help.

Where this number comes from

The Moon crosses its highest point in the sky about 50 minutes later each day, so one lunar day lasts about 24 hours 50 minutes. 1 ÷ 89,428 seconds, doubled 24 times, is 187.61 Hz. That is an F♯, about 24 cents above standard tuning.

  1. Step 1. Start with the length of the cycle

    Time between successive lunar culminations: 24 hours, 50 minutes, 28.33 seconds.

  2. Step 2. Turn it into a frequency

    One divided by that many seconds is 1.12 × 10⁻⁵ Hz. That is far too slow to hear.

  3. Step 3. Double it 24 times

    Doubling a frequency raises it by one octave: the same note, higher. After 24 doublings it is 187.61 Hz.

  4. Step 4. Name the note

    187.61 Hz is an F♯, 24 cents above standard tuning. A cent is one hundredth of the step between two neighboring piano keys. To play in tune with this tone, an instrument sets its A to 446.20 Hz instead of 440.

  5. Step 5. Keep doubling and the number lands in the range of light

    41 more doublings give the frequency of light with a wavelength of 727 nm, which is red. This is arithmetic. It pairs a tone with a color; it does not show that the two are connected.

The method is Hans Cousto’s. Planet gongs explained walks through it and says what it does and does not show.

Facts

Frequency
187.61 Hz
One cycle takes
24.84 hours
Wavelength in air (20 °C)
1.83 m
Nearest note
F♯3, 24 cents above standard tuning
Kind of statement
Octave of an astronomical cycle
Filed under
Earth, Moon & Sun

Tuning Data

The row for this tone in Hans Cousto’s tables, with the tempo and pendulum length that follow from it.

Cycle
Time between successive lunar culminations
Length of the cycle
24 hours, 50 minutes, 28.33 seconds
Octaves up
24
Concert pitch (A)
446.20 Hz
Difference from A = 440 Hz
+24.24 cents
Tempo
87.94 beats per minute
Pendulum length
11.6 cm / 4.55 in
Color by octave
Red (727 nm)
Tempo and pendulum length, octave by octave
OctaveFrequencyOne cycleTempoPendulum
17tempo1.47 Hz682.27 ms87.94 BPM11.6 cm
182.93 Hz341.13 ms175.88 BPM2.9 cm
195.86 Hz170.57 msToo fast to countToo short to build
2011.73 Hz85.28 msToo fast to countToo short to build
2123.45 Hz42.64 msToo fast to countToo short to build
2246.90 Hz21.32 msToo fast to countToo short to build
2393.81 Hz10.66 msToo fast to countToo short to build
24tone187.61 Hz5.33 msToo fast to countToo short to build
Intervals built on this tone
RatioIntervalFrequencyNoteConcert ACents from 440
1/1Perfect unison187.61 HzF#3446.21 Hz+24.28
81/80Syntonic comma189.96 HzF#3451.79 Hz+45.79
531441/524288Pythagorean comma190.17 HzF#3452.30 Hz+47.74
128/125Diesis192.11 HzG3431.28 Hz-34.66
648/625Greater diesis194.51 HzG3436.67 Hz-13.16
25/24Chroma195.43 HzG3438.72 Hz-5.05
16/15Diatonic semitone200.12 HzG3449.25 Hz+36.01
10/9Minor whole tone208.46 HzG#3441.70 Hz+6.68
9/8Major whole tone211.06 HzG#3447.22 Hz+28.19
8/7Septimal whole tone214.41 HzA3428.82 Hz-44.55
6/5Minor third225.13 HzA3450.26 Hz+39.92
5/4Major third234.51 HzA#3442.70 Hz+10.59
4/3Perfect fourth250.15 HzB3445.71 Hz+22.32
3/2Perfect fifth281.42 HzC#4446.72 Hz+26.23
8/5Minor sixth300.18 HzD4449.76 Hz+37.97
5/3Major sixth312.68 HzD#4442.20 Hz+8.64
7/4Natural seventh328.32 HzE4438.25 Hz-6.89
16/9Pythagorean minor seventh333.53 HzE4445.21 Hz+20.37
9/5Just minor seventh337.70 HzE4450.77 Hz+41.88
15/8Major seventh351.77 HzF4443.20 Hz+12.55
2/1Octave375.22 HzF#4446.21 Hz+24.28

Source notes

The Moon rises about 50 minutes later each day, making the culmination period longer than the solar day.

Source: Hans Cousto — Tuning Data / Sun Earth Moon Planets. View the source PDF.

License: CC BY-NC-ND 4.0, as stated in Stimmdaten.pdf (German edition), page 2.

Values are reproduced from Cousto’s tables. Tempo, pendulum length and interval tables are calculated by this site from those values.

See every tone in the tables: Open the tuning data reference.

Sources

More about the pitch

The same note in every octave

Each step doubles or halves the frequency. Tap one to hear it.

Entries close in pitch

Within 35 cents of this tone, in any octave. A cent is one hundredth of the step between two neighboring piano keys. Being close in pitch does not mean two things are connected.

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