Answer:
For us to see the full Moon lit up, the positions of the Sun, the Moon, and Earth must be in a specific alignment known as the "syzygy." This occurs when the Earth is located between the Sun and the Moon, with the Moon on the opposite side of the Earth from the Sun.
During this alignment, the Sun's light shines directly onto the entire face of the Moon that is visible from Earth, illuminating it fully and making it appear as a bright, circular disk. This is because the Moon does not produce its own light but reflects the Sun's light back to us on Earth.
It's important to note that the full Moon is visible from Earth for only one night, but it can appear almost full for several nights before and after the actual full Moon due to the angles between the Sun, the Moon, and the Earth changing over time.
Step-by-step explanation: