WorldAugust 12, 2026
penumbra
peh-NUM-bruh
Definition
The partially shaded outer region of a shadow cast by an opaque object, specifically where the light source is only partially blocked.
Etymology
Derived from the Latin 'paene' meaning 'almost' and 'umbra' meaning 'shadow', the term was coined in the 17th century to describe the lighter part of a shadow.
In the news
The article uses the term to distinguish between the area of total darkness (the umbra) and the lighter, outer shadow (the penumbra) created during a solar eclipse. Understanding this difference helps viewers determine whether they will see a total or partial eclipse.
Europe’s total solar eclipse: the best place to see it and how to view it safely
Read the full article ↗The Guardian