penumbra

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penumbra

(pĭnŭm`brə): see eclipseeclipse
[Gr.,=failing], in astronomy, partial or total obscuring of one celestial body by the shadow of another. Best known are the lunar eclipses, which occur when the earth blocks the sun's light from the moon, and solar eclipses, occurring when the moon blocks the sun's light
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; sunspotssunspots,
dark, usually irregularly shaped spots on the sun's surface that are actually solar magnetic storms. The spots are darker because the temperature of the spots is lower than that of the surrounding photosphere (the visible surface of the sun).
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.

penumbra

(pi-num -bră)
1. See umbra.
2. See sunspots.

Penumbra

 

the space between regions of total shadow and total light formed behind an opaque body illuminated by a light source whose dimensions are comparable both with the dimensions

Figure 1

of the body and with the distance from the light source to the body (see Figure 1). Only part of the light source is visible in the penumbra; the light source is not visible in the umbra and is completely visible in the region of total light. The point of observation of a partial solar eclipse is within the penumbra formed by the moon as illuminated by the sun.

penumbra

[pə′nəm·brə]
(astronomy)
The outer, relatively light part of a sunspot.
(optics)
That portion of a shadow illuminated by only part of a radiating source.

penumbra

1. a fringe region of half shadow resulting from the partial obstruction of light by an opaque object
2. Astronomy the lighter and outer region of a sunspot
3. Painting the point or area in which light and shade blend
References in periodicals archive ?
This penumbral eclipse is something beautiful to see.
of a penumbral constitution "[b]ecomes just a restatement of the
When all of the Moon escapes the umbra, only the last, penumbral shading is left for stage five.
By Aug 20 the group was type Dao consisting of several small penumbral sunspots but by Aug 22 had started to fade.
Specifically, in the transient MCAO model, collateral circulation is significantly reduced by transient occlusion of both CCAs, possibly preventing activation of neuroinflammatory cascade in penumbral areas.
A penumbral eclipse occurs when the Moon passes through the Earth's penumbra.
Chapters address specific questions such as the role of glutamate/NMDA, the mechanisms of penumbral cells, the importance of intermittent hypoxia, and gene regulation under stressful conditions.
Given the penumbral riches, both historical and invented, that dance around the core narrative of the film, the college debates themselves barely register: the positions are repeatedly stacked in favor of Wiley, the interactions of the team are merely sketched, and deeper pedagogical questions of lasting importance remain buried.
A partial eclipse will be seen within the much broader path of the moon's penumbral shadow, which includes northeastern North America, and most of Europe and Asia," it added.
The survey is accompanied by a handsome artist's book, Frances Stark: Collected Works (Walther Konig, 2007), whose cover reproduces a collage containing a drawing of an apple emblazoned with the text, "Agonizing yet blissful little orgies of soul probing" (the apple stalk is rendered photographically, with a chrysalis of a penumbral butterfly attached to it).
The photographs in themselves provide a rich resource for study of these monuments, which are located in penumbral interiors, are elevated, and thus difficult to see with the naked eye.