Penumbra

Umbra & penumbra

The penumbra is that part of the shadow where the light source is only partially blocked. Part of the light passes through the edges of the object causing a partial shadow. The penumbra (Latin for almost-shadow) is the portion of a shadow that results from the source of illumination being only partially blocked. Penumbras occur only when the source of light is not a point-source. As the sun is a visible disc, solar shadows have penumbras. The penumbra part of a shadow is contrasted with the umbra part of the shadow in which the light source is completely blocked.

The part of the penumbra where an annular eclipse is visible is called the antumbra.

Also, the penumbra is the lighter, fuzzier outer edge of a shadow. The shadow is darkest at the umbra, near the object, and weakest at the penumbra, at the edge.

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Other meanings

The penumbra is also the ring-shaped semi-bright region of a sunspot that surrounds the darker umbra.
The Penumbra is also a region in the Umbra, the spirit world of the World of Darkness line of role-playing games.
"Penumbra" is an episode of .
An area in which something exists to a lesser or uncertain degree: "The first nine amendments to the Bill of Rights have a penumbra where privacy is protected from governmental intrusion.” - Griswold v. Connecticut, U.S. Supreme Court
There is a cycle of cards in the game that creates a shadow-like token of itself upon death.
Penumbra is a free horror adventure game by Frictional Games.
The ischemic penumbra is the zone around an ischemic brain infarct which receives some degree of collateral circulation.
Penumbra or Umbra was probably the start of the names "Umbris" and "Panumbris" in the MMORPG Asheron's Call.
"Penumbra" is the title of the first chapter in The Longest Journey.

Penumbra

Other meanings

See also