An Etymological Dictionary of Astronomy and Astrophysics
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A unit of → frequency, equal to 10⁶ Hz.

→ giga-; → hertz.

A zone around a → star where the → temperature would be in the range 0-100 °C to sustain → liquid water on the surface of rocky planets (or sufficiently large moons). Water is thought to be a necessary component to the → formation and evolution of Earth-type life. This zone depends on the parent star's luminosity and distance; it will be farther from hotter stars. A more accurate definition of HZ needs to include other factors, such as orbital → eccentricity, heat sources other than stellar irradiation, and atmospheric properties. Same as → circumstellar habitable zone; → ecosphere.

→ habitable; → zone.

The SI unit of frequency, defined as a frequency of 1 cycle per second.

After Heinrich Rudolf Hertz (1857-1894), the German physicist, who made several important contributions to the study of electromagnetism.

A unit of → frequency, equal to 10³ Hz.

→ kilo-; → hertz.