Microhertz

Microhertz is a unit of frequency in the International System of Units (SI). It is defined as one millionth of a hertz, or 10⁻⁶ Hz. A hertz is the unit of frequency equal to one cycle per second. Therefore, one microhertz represents one cycle occurring every million seconds.

The prefix "micro" signifies a factor of 10⁻⁶, meaning it is a very small unit of frequency. Consequently, microhertz is used to describe extremely slow oscillations or periodic phenomena. Examples of such phenomena include the very slow variations in the Earth's rotation, geological processes that occur over millennia, or the extremely low-frequency signals detected in some astronomical observations.

While hertz is a commonly used unit for everyday frequencies like radio waves or sound waves, microhertz is reserved for applications where the rate of repetition is exceptionally low. The practical applications are specialized, often found in fields like geophysics, astronomy, and certain areas of precision metrology where the measurement of very long-term cycles is crucial. The inverse of microhertz is the megasecond (Ms), which is one million seconds.