Which phase of the moon is visible from Earth when the moon, earth, and sun are aligned?

When the moon, Earth, and sun are aligned in a straight line, the phase of the moon that is visible from Earth is the new moon. During this phase, the moon is positioned between the Earth and the sun, which means the side of the moon that is illuminated by the sun is facing away from the Earth. As a result, the moon is not visible from our perspective, leading to the new moon phase.

It is important to note that the alignment of the three celestial bodies also influences the occurrence of solar eclipses, which can happen during a new moon. In contrast, a full moon occurs when the Earth is positioned between the sun and the moon, allowing the fully illuminated side of the moon to be visible. The first quarter and last quarter phases are neither aligned nor fully illuminated, leading to their characteristic half-lit appearance.