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Name______Write the Can You Explain question here: ______

Why do we see different shapes of the from ? Period______

Discovery Techbook - Unit: Space Systems / Concept: Phases

****NOTE: Watch ALL embedded video clips and images as you progress through each page of the concept.****

***ENGAGE- Answer all questions in COMPLETE SENTENCES where appropriate. Watch all video clips and images.

Complete PHASES on the Engage page then answer the questions below.

1. Which statements are correct about moon phases? Select all correct answers. a. Full generally occur once a b. Full moons generally occur once a c. A is the name of the phase used when a full circle is seen d. A full moon is the name of the phase used when a full sphere is seen e. A occurs once a week f. A new moon occurs once a month g. A new moon is the name of the phase used when a full circle is seen h. A new moon is the name of the phase used when no part of the moon that we see from Earth is lit

The role of the in moon phases

2. This concept is about the phases of the moon. However, you also will learn about the sun. What is the connection between the sun and the phases of the moon? The moon does not produce its own light. It reflects the light from the sun ______3. Describe the different shapes of the moon you have observed in the . You also may draw the different shapes you have seen.

4. Why do you think we see different shapes of the moon at night? ______

***EXPLORE p1/2- Answer all questions in COMPLETE SENTENCES where appropriate. Watch all video clips and images. How Does the Appearance of the Moon in the Sky Change over Time? / How Does the Moon Move in Space?

The lunar cycle describes the order in which the moon’s phases happen. It is the name given to the pattern of change in the moon’s appearance. It is called a cycle because the pattern repeats itself. A full cycle is completed when the moon goes from one new moon phase to the next new moon phase.

The lunar cycle can be divided into eight phases: 1. New moon: During the new moon, the entire side of the moon facing us is dark. 2. Waxing (increasing) : We see only a sliver of the moon illuminated on the right. 3. First quarter: We see a half-circle. Half of the side of the moon facing us is lit. (We see 1/4th on the right) 4. Waxing gibbous: The moon is more than half illuminated, but is not yet full. on the right 5. Full moon: The side of the moon facing us is fully illuminated by . 6. Waning (decreasing) gibbous: The moon is again more than half illuminated, but not full. On the left 7. Last quarter: Half of the side of the moon facing us is lit. This is the half that is not lit during the first quarter. 8. Waning crescent: The last sliver of the moon is illuminated. On the left

The cycle then repeats with the appearance of another new moon.

Label the moon phases in the diagram below

3. First quarter

4. Waxing 2. Waxing gibbous crescent

5. Full moon

1. New moon

6. Waning gibbous 8. Waning

crescent 7. Last quarter or Third Quarter

The full lunar cycle takes 29.5 days. Although the moon appears to change shape, it is actually always a sphere. In addition, although the apparent shape and location of the moon change from night to night, we always see the same side of the moon. Why? The moon rotates and revolves at the same rate so the same side always faces Earth!

The term “waxing” refers to a moon that is growing in illumination. The term “waning” refers to a moon that is shrinking in illumination. Draw an imaginary line down the center of the moon at night. If the side that is illuminated would fill in the shape of a “p”, think of it as premiering on the way to a full moon or a “b” for beginning its cycle. If it fills in the shape of a lower case “d”, it’s on its way to disappear. This repeating pattern is the basis for a – our month. Moon Time

Imagine you need to track the passing of time (days, , ) just from watching the . What could you determine about time, now that you know the phases and length of the lunar cycle? Match the lengths of time to the description of what you have seen in the night sky.

1. Some time has passed since the full moon. There is no moon visible in the sky. ___ b. about two weeks have passed ______2. The moon had just a sliver of light on its left side. Now it has just a sliver of light on its right side. ___ e. about one week has passed ______3. You have seen a first-quarter moon three times now. ____a. 3 months have passed ______4. The moon was just a sliver of light on its right side. Now it’s just a sliver of light on its left side. ____ d. about 3 weeks have passed ______5. Some time has passed since the waxing gibbous moon. The moon is a waxing gibbous moon again. ____ c. one month has passed ______a. 3 months have passed b. about two weeks have passed c. one month has passed

d. about 3 weeks have passed e. about one week has passed

The moon’s orbital path is not on the same plane as Earth’s orbital path around the sun, it is at an incline. The moon’s orbital path is tilted 5 degrees. This is why we do not have every month. As a result, its position in the sky changes from night to night. Students may think the phases of the moon are caused by Earth’s on the moon or by the rotation of the moon. Actually, the phases occur because from Earth we see different areas illuminated by the sun as the moon revolves around Earth. Half of the moon is always illuminated, we just don’t see it from our viewpoint. What moon phase do we call it when we do see the half that is illuminated? ____A full moon______Explaining the moon phases

Study the image. Using what you have learned about the phases of the moon, write a short paragraph in the space below explaining what the image shows and what causes the phases.

***EXPLORE p3- Answer all questions in COMPLETE SENTENCES where appropriate. Watch all video clips and images.

Why Does the Moon Have Different Phases?

The moon itself does not emit its own light. It shines because it’s highly reflective surface reflects the sun’s light to Earth. Sunlight only reaches the half of the moon’s surface that is facing the sun.

As the moon Earth, the arrangement of the sun, Earth, and moon in space change. For example, sometimes the moon is between the sun and Earth (new moon). A full moon is visible when Earth is between the sun and the moon. Sometimes the Earth, moon, and sun form a triangle. The phase of the moon depends on its position relative to the sun and Earth. The phases change as the moon revolves around Earth, different portions of the moon’s sunlit surface are visible from Earth. Thus, from the perspective of Earth, the appearance of the moon changes from night to night.

Not only does the apparent shape of the moon change, its position in the sky also changes. This is also a result of how it moves in space. The change in position over the course of one night is a result of Earth’s rotation. As Earth rotates from to east, everything in the sky, including the moon, appears to rise in the east and set in the west. However, although the time at which the sun rises and sets varies little from to day, the moon rises and sets at noticeably different times. Since the moon completes one revolution around Earth in 27.3 days, it moves eastward about 13 to 15 degrees along its of Earth each day. As a result, the moon appears to rise about an later each night than the previous night.

The moon takes about 27.3 days to orbit Earth. A full lunar cycle, however, takes 29.5 days. This difference between the moon’s orbiting time and a full cycle of phases is because the moon is orbiting Earth as Earth is orbiting the sun. As a result, the moon must travel a little bit farther around Earth to catch up with its relative starting position.