penumbra

penumbra
/pi num"breuh/, n., pl. penumbrae /-bree/, penumbras.
1. Astron.
a. the partial or imperfect shadow outside the complete shadow of an opaque body, as a planet, where the light from the source of illumination is only partly cut off. Cf. umbra (def. 3a).
b. the grayish marginal portion of a sunspot. Cf. umbra (def. 3b).
2. a shadowy, indefinite, or marginal area.
[1660-70; < NL, equiv. to L paen- PEN- + umbra shade]

* * *

      (from Latin paene, “almost”; umbra, “shadow”), in astronomy, the outer part of a conical shadow, cast by a celestial body, where the light from the Sun is partially blocked—as compared to the umbra (q.v.), the shadow's darkest, central part, where the light is totally excluded. The definition of the term may be extended to include the partial shadow of any large source of light or electromagnetic radiation. An observer in the penumbra sees the Sun (or other light source) partially obscured. The term also is used for the outer portion of a sunspot.

* * *


Universalium. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • penumbra — pe·num·bra /pi nəm brə/ n pl bras 1: an area within which distinction or resolution is difficult or uncertain the public private penumbra 2: an extension of protection, reach, application, or consideration; esp: a body of rights held to be… …   Law dictionary

  • Penumbra — Saltar a navegación, búsqueda Para otros usos de este término, véase Penumbra (desambiguación). Umbra, penumbra, y antumbra La umbra (en latín: sombra ) es la parte más oscura de una …   Wikipedia Español

  • penumbră — PENÚMBRĂ, penumbre, s.f. 1. Zonă incomplet luminată, cuprinsă între zona umbrită şi cea luminoasă din spatele unui corp opac; p. gener, zonă slab luminată; semiobscuritate. 2. (pict.) Zonă de trecere între lumină şi umbră. – Din fr. pénombre. cf …   Dicționar Român

  • Penumbra — (lat. „Halbschatten“) bezeichnet: Penumbra (Astronomie), Gebiete innerhalb von Sonnenflecken, die dunkler als die restliche Sonnenoberfläche sind vereinzelt auch den Halbschatten bei einer Mondfinsternis Penumbra (Medizin), die bei einem… …   Deutsch Wikipedia

  • penumbra — sustantivo femenino 1. (no contable) Sombra débil entre la luz y la oscuridad: La habitación estaba en penumbra. Al entrar, en la penumbra del pub no se veía nada. 2. (no contable) Área: astronomía En los eclipses, zona parcialmente iluminada… …   Diccionario Salamanca de la Lengua Española

  • Penumbra — Pe*num bra, n. [NL., fr. L. paene almost + umbra shade.] 1. An incomplete or partial shadow. [1913 Webster] 2. (Astron.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of… …   The Collaborative International Dictionary of English

  • penumbra — Pe*num bra, n. [NL., fr. L. paene almost + umbra shade.] 1. An incomplete or partial shadow. [1913 Webster] 2. (Astron.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of… …   The Collaborative International Dictionary of English

  • penumbra — 1660s, from Mod.L. penumbra partial shadow outside the complete shadow of an eclipse, coined 1604 by Kepler from L. pæne almost + umbra shadow (see UMBRAGE (Cf. umbrage)) …   Etymology dictionary

  • penumbra — s. f. 1.  [Física] Estado de uma superfície incompletamente iluminada por um corpo luminoso cujos raios são em parte interceptados por um corpo opaco. 2.  [Por extensão] Meia luz. 3.  [Belas Artes] Ponto de transição da luz para a sombra.… …   Dicionário da Língua Portuguesa

  • Penumbra — Penumbra, der Halbschatten, der die meisten Sonnenflecke umgibt (s. Sonne) …   Meyers Großes Konversations-Lexikon

  • Penumbra — (lat.), s. Sonnenflecke …   Kleines Konversations-Lexikon

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”