what is darkest place of a shadow and lightest place of a shadow

The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. For a point source only the umbra is cast. The umbra (Latin for "shadow") is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. The penumbra (from the Latin paene "almost, nearly") is the region in which only a portion of the light source is obscured by the occluding body. An observer in the penumbra experiences a partial eclipse. An alternative definition is that the penumbra is the region where some or all of the light source is obscured. The antumbra (from Latin ante, "before") is the region from which the occluding body appears entirely contained within the disc of the light source.

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