Umbra

An umbra is the darkest part of a shadow cast by an object blocking light, such as during a solar or lunar eclipse. It occurs where the light source is completely obscured behind the object, creating a region of full shadow. In a lunar eclipse, the Earth’s umbra darkens the Moon, while in a solar eclipse, the Moon’s umbra creates a path of total darkness on Earth. The umbra is contrasted with the penumbra, where only part of the light is blocked, producing a lighter shadow. It helps explain the varying darkness and visibility observed during eclipses.