An eclipse occurs when one astronomical object, such as a moon or planet, moves into the shadow of another one. As the Moon orbits around the Earth, sometimes the Moon lands between the Sun and Earth. When this happens, the Moon blocks the light of the Sun from reaching Earth, causing a solar eclipse. During a solar eclipse, the Moon casts a shadow onto Earth.
For a total eclipse to occur, the Sun, Moon, and Earth must be in a direct line. During a total eclipse, the Moon lines up perfectly to fully obscure the Sun, resulting in "totality." A total solar eclipse is only visible from a small area on Earth. The sky becomes very dark, as if it were night.