Breadcrumb Home > Word of the Day Quiz Cite What Does It Mean? penumbra During an eclipse, the earth's penumbra darkens the sky. How is this possible? The earth casts a partial shadow across the moon. The earth emits a gaseous cloud that blocks the moon's illumination. The earth deviates from orbit, blocking the moon for several minutes. Fact Monster Word Quiz for Kids Infoplease Daily Almanac
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