What celestial event occurs when Earth passes between the Sun and the Moon?

The correct answer is a lunar eclipse, which occurs when the Earth is positioned directly between the Sun and the Moon. During this alignment, the Earth's shadow is cast onto the Moon, causing it to darken somewhat. Depending on the alignment and the relative distances, the Moon can take on a reddish hue, a phenomenon often referred to as a "blood moon."

This event can only take place during a full moon phase when the Sun, Earth, and Moon are aligned in a straight line. The Earth's shadow has two parts: the umbra, where a total eclipse can occur, and the penumbra, where a partial eclipse might be observed. This distinctive alignment distinguishes lunar eclipses from other celestial events.

In contrast, a solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun's light. The transit of Venus is a distinct event wherein Venus passes directly between the Earth and the Sun, appearing as a small dot moving across the solar disk. Planetary alignment refers to the arrangement of multiple planets in a straight line or near position in the sky, which is unrelated to the positioning of the Earth, Moon, and Sun that causes a lunar eclipse.