An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : umbra
antumbra
  پادسایه   
pâdsâyé

Fr.: anti-ombre   

That part of the Moon's shadow that extends beyond the → umbra. It is similar to the → penumbra in that the Sun is only partially blocked by the Moon. From within the antumbra, the Sun appears larger than the Moon which is seen in complete silhouette. An → annular eclipse is seen when an observer passes through the antumbra (F. Espenak, NASA).

anti- + → umbra.

penumbra
  نیمسایه   
nimsâyé (#)

Fr.: pénombre   

1) The portion of a shadow in which light from an extended source is partially but not completely cut off by an intervening body; the area of partial shadow surrounding the umbra.
2) The lighter part of a shadow during an eclipse. An observer standing in the penumbra of a Solar eclipse will see a partial eclipse.
3) The lighter zone surrounding the dark area (→ umbra) of a → sunspot. It consists of fine, light filaments which are approximately radial for sunspots with circular outline, but irregular for complex spots.

N.L., from L. pæne "almost" + → umbra "shadow."

Nimsâyé, from nim "mid-, half" (Mid.Pers. nêm, nêmag "half;" Av. naēma- "half;" cf. Skt. néma- "half") + sâyé, → shadow; →umbra.

penumbral
  نیمسایه‌ای   
nimsâye-yi (#)

Fr.: pénombral   

Of or relating to a → penumbra.

penumbra; → -al.

penumbral lunar eclipse
  ماه‌گرفت ِ نیمسایه‌ای   
mâhgereft-e nimsâye-yi

Fr.: éclipse de lune pénombrale   

A lunar eclipse that occurs when the Moon passes through the Earth's → penumbra, but misses the darker umbral shadow. Because the Moon is only partially dimmed, a penumbral eclipse is not impressive. Total penumbral eclipses are rare, and when these occur, that portion of the Moon which is closest to the umbra can appear somewhat darker than the rest of the Moon.

penumbral; → eclipse.

umbra
  سایه   
sâyé (#)

Fr.:ombre   

1) Optics: A dark area, especially the blackest part of a shadow from which all light is cut off. → penumbra.
2) Sun: The central darkest part of a → sunspot, which is also the coolest part (~ 4,200 K).

From L. umbra "shade, shadow."

Sâyé "shadow," from Mid.Pers. sâyak "shadow;" Av. a-saya- "throwing no shadow;" Skt. chāya- "shadow;" Gk. skia "shade;" Rus. sijat' "to shine;" M.H.G. schinen, O.H.G. skinan, Ger. Schein "glow, shine;" PIE base *skai- "bright."