Definition of penumbra in English:
noun (plural penumbrae /-briː/ or penumbras)
1The partially shaded outer region of the shadow cast by an opaque object.
- In other cases the Moon does not pass through the umbra at all, just going through the penumbra (a region of partial shadow).
- And we would do well to remember that the penumbra is the lighter, outer region of the shadow, the halo, indeed, of the shadow.
- The Moon begins to enter the Earth's outer shadow, or penumbra, at 9: 06 P.M.
1.1 Astronomy The shadow cast by the earth or moon over an area experiencing a partial eclipse.
- On Friday morning, the moon will enter the penumbra of the Earth's shadow at 3: 05 am, and the moonlight will become dimmer.
- So, one will observe either a total eclipse by the umbra (which can be well observed), a partial eclipse by the umbra and penumbra, or a total or partial eclipse by the penumbra only.
- The Moon on April 24th will glide through Earth's penumbra, producing what astronomers call a ‘penumbral lunar eclipse.’
2A peripheral or indeterminate area or group: an immense penumbra of theory surrounds any observation
More example sentences
- Like many words in everyday use, it carries with it, as it were, a penumbra of different shades of meaning.
- Others tell different jokes that are incoherent except in the penumbra cast by the joke.
- He had a sound belief in astrology, the stars being the twinkling penumbra of his incandescent belief in the ‘free market,’ with whose motions it was blasphemous to tamper.
- Example sentences
- I think it's important that we recognize the existence of this problematic, penumbral group, but that doesn't mean that there aren't people who do take responsibility.
- Rick would howl, and then rapidly half-wade, half-swim down the penumbral corridor and stumble up onto the next sandbank, laughing.
- The nearly flat trail was bordered on one side by precipitous slopes, where penumbral snowfields fell into the crater 100 feet below.
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