Here's why:

* Lunar Eclipse: A lunar eclipse occurs when the Earth is positioned directly between the Sun and the Moon, casting its shadow onto the Moon. But for this to happen, the Moon needs to be at a specific point in its orbit – at or very near the intersection of its orbital plane with the Earth's orbital plane (called the "nodes"). If the Moon is above or below these nodes during a full moon, the Earth's shadow will miss it.

* Solar Eclipse: A solar eclipse occurs when the Moon is positioned directly between the Sun and the Earth, casting its shadow onto the Earth. Again, the Moon must be at or very near the nodes of its orbit for this to happen. If the Moon is above or below these nodes during a new moon, it will pass above or below the Sun, and no eclipse will occur.

Since the Moon's orbit is tilted, it doesn't align with the Sun and Earth perfectly at every new or full moon. This means that the Moon typically passes above or below the Sun's shadow during a new moon and above or below the Earth's shadow during a full moon.