Diagram of a large light source and a smaller occulting body, showing the relationships between the umbra, the region that receives no light from the source, so that it is fully shaded, the penumbra that receives light from only one part of the rim of the source, so that it is partly shaded, and the antumbra, that is so far from the occulting body that it receives light from the rim all the way around the source, though not from the full area of the light source.
