# Dictionary:Hour angle

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{{#category_index:H|hour angle}}
Angular distance of a body west of the projection of a meridian onto the celestial sphere. **Local hour angle** is the angle between a body and the projection of the observer’s meridian onto the celestial sphere. **Greenwich hour angle** is with respect to the projection of the Greenwich meridian. **Sidereal hour angle** is angular distance west (unlike the others that are measured east) of the vernal equinox; it is thus the supplement of right ascension.