<em>The moon comes between the Sun and Earth.</em>
Explanation:
<em>A lunar eclipse takes place only when the Moon passes directly at the back of the Earth's shadow.</em>
<em>This can work only when the Moon, Sun, and Earth are closely or exactly closely in place, and the Earth is in between the Sun and Moon. A lunar eclipse can appear only when the moon is full at night.</em>
<em>The length and type of a lunar eclipse depend on the Moon's closeness to either node of its orbit.</em>