Something related to, connected to, and implied by, the existence of something else that is necessary for the second thing to be full and complete in its essential aspects
The foregoing cases suggest that specific guarantees in the Bill of Rights have penumbras, formed by emanations from those guarantees that help give them life and substance.
The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra, or perfect shadow, on all sides, and the full light
paena = [Latin] almost; umbra = [Latin] shadow A penumbra is an annulus (thick ring) around the umbra of a sunspot The penumbra is less dark than the umbra, but is darker than granulation The penumbra appears to be built up of many fibers that point away from the center of the sunspot The high-resolution continuum image shows a big sunspot with a penumbra
The sunspot area that may surround the darker umbra or umbrae In its mature form it consists of linear bright and dark elements radial from the sunspot umbra
The portion of a shadow that is only partially shaded We would see part of the sun peeking around Earth's edge In the penumbra, the sunlight is dimmed but not extinguished
That part of a shadow due to a light source which receives partial illumination from the source By definition the source will be an extended light source and the penumbra always surrounds the umbra
Means, literally, "dim light" It most often refers to the outer shadow cast during eclipses, and defines the region of shadow which gives rise to a partial eclipse It is also the lighter area surrounding the central region of a sunspot
the region close to the radiation field edge The penumbral width is typically defined by the distance between the points where 20% and 80% of the dose at central axis is delivered A small penumbra means a good beam definition which allows to give maximum dose to a target volume with a rapid dose fall off next to it towards the surrounding normal tissue