...It is bordered onboth sides by the spectrum of the penumbra, which is much brighterthan that of the umbra, but fainter than that of the adjoining regionsof the sun... 
Robert Stawell Ball 「The Story of the Heavens」
...The penumbra of a spot was formed by the thinner parts of theatmosphere about the vacancy which surrounded the nucleus...
Edward Singleton Holden 「Sir William Herschel: His Life and Works」
... The time occupied by the Moon in passing throughthe penumbra, before and after a lunar eclipse, will generallyrun to about an hour for each passage...
George Chambers 「The Story of Eclipses」
...Wherever the penumbra falls there will be a solareclipse of some kind, and the nearer the place is to the axisof the penumbra, the more nearly total will be the eclipse...
George C. Comstock 「A Text-Book of Astronomy」
...The darkest portion of the penumbra is its external edge, whichstands out conspicuously against the adjoining bright surface of theSun...
Thomas Orchard 「The Astronomy of Milton's 'Paradise Lost'」
...The shadow of the fourth, for instance, isnearly all penumbra, the really black part being quite minute bycomparison...
Richard A. Proctor 「Half-hours with the Telescope」
...The penumbra attending the earth's shadow is usually supposed to render this observation uncertain to two or three minutes of time, or more than half a degree of longitude...
Matthew Flinders 「A Voyage to Terra Australis」
ランダム例文：
便利！手書き漢字入力検索
この漢字は何でしょう？？
時事ニュース漢字 📺