The
penumbra (
Latin for mid-
shadow) is the portion of a shadow that results from the source of
illumination[?] being only partially blocked. Penumbras only occur when the source of light is not a point-source. As the
sun is a visible disc, solar shadows have penumbras. The penumbra part of a shadow is contrasted with the
umbra part of the shadow in which the light source is completely blocked.
See also: eclipse.