if the earth is in between the sun and the moon, then the earth can block the light on the moon & the full moon is when the earth is in between the sun and the moon -> the part sun is when the space can unblock the sound on the sun the full moon is when the earth can block the light on the moon  the full moon is when the earth can block the light on the moon & an object blocking light causes a shadow -> the part sun is when the space can effect a shadown on the sun the full moon is when the earth can cause a shadown on the moon  the part sun is when the space can effect a shadown on the sun & a lunar eclipse is formed by earth 's shadow falling on the moon -> the full moon is when a lunar eclipase can happen