Chapter 14 Section 6 What are the phases of the Moon? Objective Identify the different phases of the Moon

Phases of the Moon From Earth, the Moon sometimes looks round. Other times, it looks like a thin sliver. The Moon appears to change shape because of the way it reflects light from the Sun. The changing shapes of the Moon are called phases. These phases depend on the positions of the Sun, the Moon, and Earth.

IDENTIFY Why does the Moon appear to change shape?

Waxing Phases When the side of the Moon facing Earth is dark, it appears as if there is no Moon at all. This is called a new Moon. As the Moon revolves around Earth, a small part of it becomes visible. As the visible part of the it increases, the Moon is said to be waxing.

Waxing Phases The first phase is called the crescent phase. During the crescent phase, less than half of the Moon is visible. When the Moon has moved one-quarter of the way around Earth, it enters the first quarter phase. This means that half of the side of the Moon facing Earth is visible.

Waxing Phases As the Moon continues in its orbit, more and more of the side facing Earth becomes visible. This is called the waxing gibbous phase. During the gibbous phase, more than half of the Moon is visible.

Waxing Phases Finally, the Moon completes half of its trip around Earth. The whole side facing Earth is visible. This is the full Moon.

2. DEFINE What is the Moon’s gibbous phase?

Waning Phases As the Moon continues to move around Earth, less and less of the surface becomes visible. The Moon is waning. After the full Moon, the Moon enters the waning gibbous phase. At the last quarter phase, only half of the Moon’s surface facing Earth is visible. The last phase of the Moon is waning crescent phase.

Waning Phases The Moon take 29 ½ days to go through all of its phases. This is a little longer than the time for one revolution of the Moon around Earth. The reason for this is that as the Moon orbits Earth, the two bodies are also moving around the Sun. The Moon must travel a little further to get directly between Earth and the Sun.

3. COMPARE When does the waxing and waning crescent phases of the Moon take place?

Classwork CHECKING CONCEPTS The moon reflects light from the ___. The phases of the Moon depend on the positions of Earth, ___, and the Sun. During the ___ phase of the Moon, half of the side of the Moon facing Earth is visible. When the Moon has finished half of its revolution around Earth, the Moon is called a ___ Moon. The Moon goes through all of its phases in ___ days.

Classwork THINKING CRITICALLY 6. CONTRAST: How do the crescent phase and the quarter phase of the Moon differ? 7. PREDICT: What would the Moon look like if it did not reflect light from the Sun? 8. SEQUENCE: List the eight phases of the Moon in order, beginning with the new Moon.