An eclipse occurs when one celestial body passes in front of another and casts a shadow. A solar eclipse happens when the moon passes between the earth and sun, casting its shadow on earth. There are three types of solar eclipses: total, partial, and annular. A total solar eclipse can only be seen within the moon's dark umbral shadow. A lunar eclipse occurs when the earth passes between the sun and moon, casting its shadow on the moon. The three types of lunar eclipses are: total, partial, and penumbral. Eclipses can only occur during a new moon for a solar eclipse or full moon for a lunar eclipse.