Rays of light from the moon; shafts of moonlight, often used poetically.
Compound word: 'moon' + 'beam' (ray of light). Poetic term used in English literature since at least the 1600s.
Moonbeams are romantic precisely because they're scientifically less real than sunbeams—the moon just reflects sunlight, so 'moonbeams' are sunshine with an imposter syndrome.
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