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Penumbra
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Diagram showing a lunar eclipse with the Sun on the left, Earth in the center casting a shadow, and the Moon passing through Earth's umbra (total shadow) and penumbra (partial shadow). Diagram showing a solar eclipse, with the Sun, Moon, and Earth aligned. The Moon casts a dark umbra shadow on Earth for a total eclipse and a lighter penumbra for a partial eclipse.
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Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.
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Penumbra

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Penumbra, (from Latin paene, “almost”; umbra, “shadow”), in astronomy, the outer part of a conical shadow cast by a celestial body, in which the light from the source is partially blocked—as compared to the umbra (q.v.), the shadow’s darkest, central part, where the light is totally excluded. During an eclipse of the Sun, an observer in the penumbra sees the Sun partially obscured. The term also is used for the outer annulus of a sunspot. See also eclipse; solar eclipse; lunar eclipse.