When does a eclipse occur?
A lunar eclipse occurs when the Earth is between the Sun and the Moon and the Earth’s shadow is cast on the Moon. From Earth is seems as if all or part of the Moon is darkened out. If you were on the moon, you would be experiencing a solar eclipse, as Earth would be blocking the Sun’s light. A Lunar eclipse can only happen when the Moon is full, as that is the only time it is on the complete opposite side of Earth than the Sun is. There is not an eclipse at every full moon.