Penumbra

usgb/pəˈnʌmbrə/
noun

The partly dark area around the shadow of an object where the light is only partially blocked.

During the solar eclipse, we were in the penumbra, not the full shadow, so it wasn't completely dark.
Visual representation of "penumbra" - The partly dark area around the shadow of an object where the light is only partially blocked

Often appears as...

  • lunar penumbra
  • solar penumbra
Definition 1 of 3
Visual representation of "penumbra"
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Shadow Clarity

Penumbra refers to a shadow's blurry part, not the darkest area.

Illustration for Shadow Clarity
The garden was cast in a soft penumbra by the tall trees.
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Light Gradients

Penumbra indicates a gradual change from light to darker shadow.

Illustration for Light Gradients
The penumbra created a gentle transition from sunlight to shade.
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Eclipse Understanding

During eclipses, 'penumbra' is often mentioned to describe partial shadowing.

Illustration for Eclipse Understanding
Observers outside the umbra will experience the eclipse in the penumbra.
Visual representation of the word "Penumbra"

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