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umbra

 
Dictionary: um·bra   (ŭm'brə) pronunciation
n., pl., -bras, or -brae (-brē).
  1. A dark area, especially the blackest part of a shadow from which all light is cut off. See synonyms at shade.
  2. Astronomy.
    1. The completely dark portion of the shadow cast by the earth, moon, or other body during an eclipse.
    2. The darkest region of a sunspot.

[Latin, shadow.]

umbral um'bral adj.

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Thesaurus: umbra
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noun

    Comparative darkness that results from the blocking of light rays: penumbra, shade, shadow, umbrage. See light/darkness.

WordNet: umbra
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: a region of complete shadow resulting from total obstruction of light


Wikipedia: Umbra
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Umbra, penumbra and antumbra.
Example of umbra, penumbra and antumbra outside astronomy.

The umbra, penumbra and antumbra are the names given to three distinct parts of a shadow, created by any light source. For a point source only the umbra is cast.

These names are usually used when referring to the shadows cast by celestial bodies.

Contents

Umbra

The umbra (Latin for "shadow") is the darkest part of the shadow. From within the umbra, the source . In astronomy, an observer in the umbra is said to be in the shadows experiencing total eclipse.

Penumbra

The penumbra (from the Latin paenes "almost, nearly" and umbra "shadow") is the region in which only a portion of the occulting body is obscuring the light source. An observer in the penumbra experiences a partial eclipse.

An alternative definition is that the penumbra is the region where some or all of the light source is obscured (i.e., the umbra is a subset of the penumbra). For example, NASA's Navigation and Ancillary Information Facility defines that a body in the umbra is also in the penumbra.[1]

Antumbra

The antumbra is the region from which the occulting body appears entirely contained within the disc of the light source. If an observer in the antumbra moves closer to the light source, the apparent size of the occulting body increases until it causes a full umbra. An observer in this region experiences an annular eclipse.

Earth's shadow, to scale, showing the extent of the umbral cone beyond the Moon's orbit (yellow dot, also to scale).

References

  1. ^ Event Finding Subsystem Preview Navigation and Ancillary Information Facility.

Translations: Umbra
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Dansk (Danish)
n. - umbra

Nederlands (Dutch)
(slag-/kern)schaduw, umbra (schaduwkegel), schim

Français (French)
n. - ombre, (Phys) pénombre, fantôme, spectre

Deutsch (German)
n. - Kernschatten, Umbra

Ελληνική (Greek)
n. - (αστρον., φυσ.) σκιά

Italiano (Italian)
ombra

Português (Portuguese)
n. - sombra (f), cone de sombra (m) (Astron.), núcleo (m) (de mancha solar)

Русский (Russian)
тень, призрак, чья-л. тень, постоянный спутник

Español (Spanish)
n. - cono de sombra, sombra, pichihuén

Svenska (Swedish)
n. - kärnskugga (astron.), umbra

中文(简体)(Chinese (Simplified))
影, 暗影, 本影

中文(繁體)(Chinese (Traditional))
n. - 影, 暗影, 本影

한국어 (Korean)
n. - 그림자, 암영부

日本語 (Japanese)
n. - 影, 影法師, 暗影部, 本影

العربيه (Arabic)
‏(الاسم) ظل, فيء, ضباب‏

עברית (Hebrew)
n. - ‮צל, ערפל, החלק המרכזי הכהה של כתם-שמש, צל כדור הארץ או הירח בעת ליקוי חמה, אורח של אורח‬


 
 

 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Thesaurus. Roget's II: The New Thesaurus, Third Edition by the Editors of the American Heritage® Dictionary Copyright © 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.  Read more
WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Umbra" Read more
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