During a full moon, the moon appears as a bright, round disk in the sky. Here's why:

* Sunlight: The moon itself doesn't emit light. The light we see is reflected sunlight.

* Position: During a full moon, the sun, Earth, and moon are aligned in a straight line, with the Earth in the middle. This means the entire sunlit side of the moon is facing Earth.

* Illumination: Because the entire sunlit hemisphere is facing Earth, we see the moon as fully illuminated.

Additional details:

* Color: The moon can appear white, yellowish, or even orangey-red depending on atmospheric conditions.

* Size: The moon appears larger when it's closer to the horizon, but this is an optical illusion. Its actual size remains constant.

* Duration: A full moon phase lasts about 3 days.

Let me know if you'd like to know more about the moon's phases!