Here's why:

* Lunar Eclipse: A lunar eclipse occurs when the Earth passes directly between the Sun and the Moon, casting a shadow on the Moon. This can only happen during a full moon when the Sun, Earth, and Moon are aligned.

* New Moon: A new moon occurs when the Moon is positioned between the Sun and Earth, and its illuminated side faces away from Earth. The Moon is not visible during a new moon.

Therefore, a lunar eclipse can only happen during a full moon, while a new moon is when the Moon is completely hidden from our view.