Concept information
Preferred term
penumbra
Definition(s)
- In general optics, a penumbra is the lighter, outer shadow of a double-shadow effect produced by a large, unfocused source of light shining on an interfering opaque object. A penumbral eclipse is one in which the eclipsed object passes through the penumbral shadow. With particular reference to solar features, a penumbra is the lighter area, marked by radial filaments, that may surround the darker, central umbra of a sunspot. Penumbral waves are waves observed in the light of H-alpha that move out from the center of a sunspot across the penumbra. (Encyclopedia of Science, by David Darling, https://www.daviddarling.info/encyclopedia/P/penumbra.html)
Broader concept(s)
Synonym(s)
- penumbrae
In other languages
-
French
URI
http://data.loterre.fr/ark:/67375/MDL-HMMK6VND-0
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