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umbra
umbra
1. The conical inner region of shadow cast by a planet or satellite, from within which the Sun's disk is completely obscured. Passage of a body through this shadow results in its eclipse as, for example, when the Moon traverses Earth's umbra. The dark umbra is surrounded by a broader penumbra (1) in which the Sun's disk is only partially obscured. 2. The central, darkest part of a sunspot. It is also the coolest part, with a temperature of about 4200 K. Umbrae are not uniformly dark but contain light umbral dots. These are smaller versions of photospheric granules, only about 300 km across, and last somewhat longer than granules, up to 25 min. They seem to be penumbral grains that have just entered the umbra. |
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"umbra." A Dictionary of Astronomy. 1997. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "umbra." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O80-umbra.html "umbra." A Dictionary of Astronomy. 1997. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-umbra.html |
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umbra
um·bra / ˈəmbrə/ • n. (pl. -bras or -brae / -ˌbrē; -ˌbrī/ ) the fully shaded inner region of a shadow cast by an opaque object, esp. the area on the earth or moon experiencing the total phase of an eclipse. Compare with penumbra. ∎ Astron. the dark central part of a sunspot. ∎ chiefly poetic/lit. shadow or darkness. DERIVATIVES: um·bral adj. |
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"umbra." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "umbra." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O999-umbra.html "umbra." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-umbra.html |
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umbra
umbra phantom, ghost XVI; uninvited guest accompanying an invited one; (astron.) shadow XVII. — L. umbra shadow, shade, phantom, etc.
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T. F. HOAD. "umbra." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "umbra." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O27-umbra.html T. F. HOAD. "umbra." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-umbra.html |
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umbra
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"umbra." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "umbra." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1E1-X-umbra.html "umbra." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-umbra.html |
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umbra
umbra
•abhorrer, adorer, Andorra, angora, aura, aurora, bora, Bora-Bora, borer, Camorra, Cora, corer, Dora, Eleonora, Eudora, explorer, fedora, flora, fora, ignorer, Isadora, Kia-Ora, Laura, Leonora, Maura, menorah, Nora, pakora, Pandora, pourer, roarer, scorer, senhora, señora, signora, snorer, soarer, Sonora, sora, storer, Theodora, Torah, Tuscarora, Vlorë
•goalscorer • cobra • okra • Oprah
•Socotra • Moira • Sudra
•chaulmoogra • supra
•Brahmaputra, sutra
•Zarathustra • Louvre • fulcra
•Tripura
•borough, burgh, Burra, curragh, demurrer, thorough
•Rubbra
•penumbra, umbra
•tundra • chakra • ultra • kookaburra
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"umbra." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "umbra." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O233-umbra.html "umbra." Oxford Dictionary of Rhymes. 2007. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-umbra.html |
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