6. Why does the moon
appear to change
shape?
The moon orbits the earth.
It takes 28 days for the moon
to go around the earth once
The only reason we can see
the moon is because it reflects
the light from the sun
Only one half of the moon is
ever lit
As the moon travels around
the earth we see different
amounts of the lit side of the
moon
7. Day 1 - New
moon
The dark side of the moon is
facing the earth
23. Day 28 - New
moon
The dark side of the moon is
facing the earth again
25. The Phases of the Moon
The dotted lines represent our line of sight from Earth
26. New Moon
The New Moon occurs when the moon is positioned between
the earth and sun. The three objects are in approximate
alignment. The entire illuminated portion of the moon is on
the back side of the moon, the half that we cannot see.
27. After the new moon, the sunlit portion is
increasing, but less than half, so it is a
WAXING CRESCENT
31. Half Moon Waxing
The first quarter and third quarter moons (both often called a "half moon"), happen when the
moon is at a 90 degree angle with respect to the earth and sun. So we are seeing exactly half of
the moon illuminated and half in shadow.
32. Waxing Gibbous
After the first quarter, the sunlit portion is still
increasing, but now it is more than half, so it is waxing
gibbous
36. Full Moon
At a full moon, the earth, moon, and sun are in approximate
alignment, just as the new moon, but the moon is on the opposite
side of the earth, so the entire sunlit part of the moon is facing us.
The shadowed portion is entirely hidden from view.
37. Half Moon Waning
The first quarter and third quarter moons (both often called a "half moon"), happen when the
moon is at a 90 degree angle with respect to the earth and sun. So we are seeing exactly half of
the moon illuminated and half in shadow.
47. New Moon
the new moon occurs when the moon is
positioned between the earth and sun. The
three objects are in approximate alignment. The
entire illuminated portion of the moon is on the
back side of the moon, the half that we cannot
see.
48. Modelling the phases of the moon
You will need:
polystyrene ball, lamp and a retort stand
Working in groups of 3 –
1. One person acts as the earth and the other holds the ball
(moon) and the other holds the lamp (sun).
2. Darken the room and aim the lamp (sun) at the ball
(moon). The student holding the moon walks around the
earth in an anticlockwise direction, holding the same side
towards the earth.
3. Try to identify each of the 8 phases of the moon as they
are seen by the person representing the earth.
4. Stop rotating briefly when each of the phases is identified
so that the positions of the sun, earth an moon can be
recorded on your worksheet.
50. Review
1. How many phases does the moon have?
2. What side of the moon do we see first?
3. What is it called when the moon appears to grow?
4. What is it called when the moon appears to get smaller?
5. How many days does it take the moon to complete a cycle?
6. Name the eight phases of the moon?
7. What is it called when you see more light in the moon (greater than
semicircle and less than a circle)?
8. What is it called when you see less light in the moon
9. What is a natural body that revolves around a planet
10. One of the shapes the moon seems to have as it orbits Earth.
11. How long does it take the earth to make one full turn on it's axis?
12. How long does the Earth's orbit take?
51. Answers
1. eight
2. dark side
3. waxing
4. wane
5. 29 1/2 days or 1 month
6. new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning
gibbous, last quarter, waning crescent
7. gibbous
8. Crescent
9. Moon
10. Phase
11. 24 Hours
12. 365 days