ocr: Lunar Eclipses During certain times, conditions permit a lunar eclipse to occur. An eclipse of the moon happens when the moon passes either entirely or partially into the shadow of the Earth. Inat total lunar eclipse, the full moon disappears slowly, only to reappear as it exits the Earth's shadow. Astronomers from long ago used lunar eclipses to show that the Earth was round. During lunar eclipses, the Earth's shadow is cast upon the surface of the moon, and the edges of the shadow are always curved. If the Earth was flat, the shadow would appear differently.
