DavePenumbra

Penumbra Introduction What is a penumbra? This is a difficult question to answer since it is not anything concrete: It is more of an absence than a presence.  It is the absence of light, and the absence of complete shadow which forms a penumbra; it is an intermediary realm between complete darkness and complete illumination. The term has its origin in the Latin paene (almost) and umbra (shadow).  It was originally used by the astronomer Johannes Kepler when analysing the refraction and occluding of light which occurs in the orbits of heavenly bodies.  But through time it has acquired a diverse repertoire of uses and meanings;  as something