What phenomenon occurs at a full moon when Earth is positioned between the moon and the sun?

The phenomenon that occurs at a full moon when Earth is positioned between the moon and the sun is the occurrence of a lunar eclipse, not auroras. During a lunar eclipse, the Earth blocks sunlight from directly reaching the moon, causing the moon to appear red or darkened as it passes through Earth's shadow. This situation specifically happens during a full moon because that is when the moon is on the opposite side of the Earth from the sun, allowing the Earth to cast its shadow onto the moon.

Auroras, on the other hand, are natural light displays predominantly seen in high-latitude regions and are caused by the interaction of solar wind with the Earth's magnetosphere, not related to the positioning of the earth, moon, and sun during a full moon. Other options like solar eclipses, meteor showers, and planetary alignments do not accurately describe the configuration of Earth, moon, and sun during a full moon.