The notions of the penumbra and umbra are important in considering eclipses (q.v.).
The umbra in the former case becomes the fully illuminated portion, and vice versa.
Each spot shows with more or less completeness a ring-shaped penumbra enclosing a darker umbra; the umbra, which looks black beside' the photosphere, is actually about as brilliant as limelight.
In a partial lunar eclipse, it partly enters the umbra and only part of its surface is darkened.
Readers of Dante know the idea that the dead have no shadows; this was no invention of the poet's but a piece of traditionary lore; at the present day among the Basutos it is held that a man walking by the brink of a river may lose his life if his shadow falls on the water, for a crocodile may seize it and draw him in; in Tasmania, North and South America and classical Europe is found the conception that the soul - o-tab., umbra - is somehow identical with the shadow of a man.