Definition of umbra in English:

umbra

Syllabification: um·bra
Pronunciation: /ˈəmbrə
 
/

noun (plural umbras or umbrae /-ˌbrē, -ˌbrī/)

  • 1The fully shaded inner region of a shadow cast by an opaque object, especially the area on the earth or moon experiencing the total phase of an eclipse. Compare with penumbra.
    More example sentences
    • When the Moon is fully immersed in the umbra a total lunar eclipse occurs.
    • If the Moon completely enters the umbra, a total lunar eclipse occurs.
    • The Moon can then pass through a part of the umbra (region of total shadow) and then there is a partial eclipse.
  • 1.1 Astronomy The dark central part of a sunspot.
    More example sentences
    • Each sunspot consists of a dark central umbra, which is estimated to have a temperature in the region of 4000°C, and a surrounding penumbra, at a temperature in the region 5000°C.
    • The darkest, central region of a sunspot, called the umbra, features tightly bundled magnetic field lines.
    • When viewed through a telescope, sunspots have a dark central region known as the umbra, surrounded by a somewhat lighter region called the penumbra.
  • 1.2chiefly • literary Shadow or darkness.
    More example sentences
    • Outlined against the setting sun, the silhouette took on a strangely surreal beauty, as if a shadow's penumbra and umbra were fused together.
    • Not once did she ask if he knew where they were going; and now, with a nettle laced gully yawning out past any shadowed umbra before them, that suddenly appeared very naive.
    • How about cleverly distracting from under-eye umbra with some beauty department illusions?

Derivatives

umbral

adjective
More example sentences
  • Further to the east and the west the observers are a few thousand miles more distant, putting them beyond the vertex of the umbral cone, so that they witness only an annular eclipse.
  • The event is a moderate partial eclipse with the Moon's northern limb dipping 15 arc-minutes into Earth's umbral shadow.
  • The Moon's trajectory takes it deep into the northern umbral shadow resulting in a total eclipse which lasts 1 hour 21 minutes.

Origin

late 16th century (denoting a phantom or ghost): from Latin, literally 'shade'.

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