1During the solar eclipse, the penumbra was visible as a lighter shadow around the darker inner shadow of the moon on the earth's surface.
2The concept of the penumbra has been used in philosophy to describe the limits of human knowledge, where our understanding is always partial and incomplete.
3The artist's use of chiaroscuro created a sense of depth and volume, with the penumbra adding a sense of mystery to the composition.
4The penumbra of doubt surrounding the company's financial dealings led to a decline in investor confidence.
5The novel explores the penumbra of human emotions, where characters' feelings are often ambiguous and open to interpretation.