A half moon, also known as a quarter moon, occurs because we only see half of the moon's illuminated surface from our perspective on Earth.
Understanding Lunar Phases
The moon doesn't produce its own light; it reflects sunlight. As the moon orbits Earth, the amount of sunlight reflecting towards us changes, creating the lunar phases we observe. According to the YouTube video "What causes the phases of the Moon?", when the moon is on the same side as the sun, we see the "new moon" phase where the moon appears dark because the side facing us is in shadow.
How a Half Moon Forms
A half moon occurs when the moon is at a 90-degree angle relative to the Earth and Sun.
- First Quarter: This phase happens about a week after the new moon, when the moon is a quarter of the way through its orbit. We see the right half of the moon illuminated.
- Third Quarter: About two weeks after the full moon, the moon reaches the third quarter phase. This time, the left half of the moon appears illuminated.
In both cases, we are only viewing half of the sunlit portion of the Moon.
Key Factors Influencing Lunar Phases
Here are some key factors that contribute to the moon's phases:
- Moon's Orbit: As the moon orbits Earth, different amounts of its sunlit surface become visible to us.
- Sunlight Reflection: The moon reflects sunlight, and the angle at which sunlight hits the moon determines the appearance from Earth.
- Earth's Perspective: Our view from Earth changes as the moon moves along its orbit, leading to various phases.
