Earth and the Moon


How does a solar eclipse occur?

A solar eclipse happens when the Moon is directly in line between Earth and the Sun. The Moon’s shadow sweeps across Earth’s surface; at those places where the shadow lands, an eclipse is seen. Like Earth’s shadow, the Moon’s shadow consists of two parts: a dark, central region called the umbra, and a lighter region called the penumbra that surrounds the umbra. Under the penumbra, a partial solar eclipse occurs. Under the umbra, a total eclipse or an annular eclipse is seen.


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