Here's a breakdown:
1. The Sun: The sun is the light source that illuminates the moon.
2. The Moon: The moon itself doesn't produce light, it reflects sunlight.
3. The Earth: We observe the moon from Earth.
Lunar Phases:
The moon orbits the Earth, and as it does, the angle between the sun, Earth, and moon changes. This changing angle causes the illuminated portion of the moon we see to change, resulting in different lunar phases.
Half Moon:
* First Quarter Moon: During the first quarter phase, the sun, Earth, and moon form a roughly 90-degree angle. This means we see exactly half of the moon illuminated, and the other half in shadow. This occurs about a week after a new moon.
* Last Quarter Moon: This phase is essentially a mirror image of the first quarter. The sun, Earth, and moon are again at a 90-degree angle, but from the other side. We see the other half of the moon illuminated. This occurs about a week after a full moon.
In summary: The half moon appears when the sun, Earth, and moon are positioned at a 90-degree angle, resulting in us seeing exactly half of the moon illuminated.
