Half is always illuminated by the Sun
Except during a lunar eclipse, sunlight illuminates one hemisphere of the Moon.
Our viewing angle changes
The visible fraction of the sunlit side changes through the orbit.
Phases are not Earth's shadow
Earth's shadow causes lunar eclipses, which are separate events.
The cycle is predictable
The sequence from new Moon through full Moon and back repeats regularly.
This page explains scientific concepts for general learning. It does not replace laboratory safety procedures, professional engineering guidance, or individualized medical advice.