1. Moon Phases Barbara Gage PSC 1210 Prince George’s Community College
animated GIF created by Antonio Cidadao
Barbara Gage PSC Prince George’s Community College

2. Intro to the moon
The moon does not produce its own light - we see the moon because it is reflecting light from the Sun.

3. Moon Phases Like Earth, the moon moves through space in 2 ways:
The Moon revolves around the Earth in 27.3 days
The Moon also rotates on its own axis in 27.3 days

4. Moon Phases A day and a year on the moon are the same length
For this reason, the same side of the moon always faces earth

5. Moon Phases
As the moon revolves around Earth, the relative positions of the moon, Earth, and sun change
The changing relative positions of the moon, Earth, and sun cause the phases of the moon and eclipses

6. Moon Phases
The different shapes of the moon you see from Earth are called phases
In about 29.5 days, the cycle is completed

7. Moon Phases
The phase of the moon you see depends on how much the sunlit side of the moon faces earth

8. 1) New Moon
The sunlit side faces away from the Earth

9. 2) Waxing Crescent
The portion of the moon you can see is waxing, or growing, into a crescent shape.

10. You can see half of the sunlit side of the moon.
3) First Quarter
You can see half of the sunlit side of the moon.

11. 4) Waxing Gibbous
The moon continues to wax. The visible shape of the moon is called gibbous.

12. 5) Full Moon
The entire sunlit side faces the Earth.

13. 6) Waning Gibbous
The portion of the moon you can see wanes, or shrinks.

14. 7) Third Quarter
You can see half of the moon’s lighted side

15. 8) Waning Crescent
You can see a crescent once again.

16. How do you know if it is a
Waning or Waxing phase?

18. Eclipses

19. Intro to Eclipses
When the Sun or Moon is blocked from the Earth an eclipse occurs.
When the sun is blocked, it is called a solar eclipse
When the moon is blocked, it is called a lunar eclipse

20. Solar Eclipse
The moon (in new moon phase) passes directly between the earth and the sun blocking the sunlight
Remember “SME”
The shadow of the Moon falling on the Earth. Anyone under the shadow will see the solar eclipse.

21. penumbra
umbra
penumbra

22. People within the umbra (or dark shadow region) see the total eclipse
People within the penumbra (or lighter shadow region) see only a partial eclipse
It is not safe to look directly at a solar eclipse (you need special glasses)

23. In a total solar eclipse, the outer layer of the sun’s atmosphere, the solar corona, is visible surrounding the dark disk of the moon
The sky grows dark as night, and an eerie color and you can see the stars

24. Lunar Eclipse
The Earth passes directly between the Moon and the Sun (during the Full Moon phase)
Remember “SEM”
Earth casts a shadow on the Moon
Everyone on Earth (at night) will see the Lunar Eclipse

25. penumbra
umbra
penumbra

26. Lunar Eclipse
When the moon is in the Earth’s umbra, you see a total lunar eclipse
When the moon is not totally in the Earth’s umbra, you see a partial lunar eclipse

27. Lunar Eclipse
During a total lunar eclipse, the moon obtains a reddish tint (also called blood moon) because the Earth’s atmosphere bends the red part of the visible sun light toward the moon
You do not need special glasses to see a lunar eclipse

28. Question?
Shouldn’t there be a lunar eclipse every time we have a full moon? (Once per month)

29. The Earth revolves around the Sun on a flat plane.
Earth’s
Earth’s
The Moon revolves around Earth on a tilted plane. This means that when the moon is full, it may be above or below the shadow of the Earth and no eclipse will occur. Two times a year, the sun, earth, and moon will align, causing an eclipse.

30. The Earth moves through space in 2 major ways: rotation and revolution
Rotation is the spinning of the Earth on its axis
It takes Earth about 24 hours to rotate once. This 24 hour cycle of day and night is called a day

31. Day and Night An Earth’s rotation causes day and night
It is day on the side of the Earth facing the sun.
It is night on the side of the Earth facing away from the sun.

32. Day
Night
sunlight

33. Year Revolution is the movement of one object around another
The earth travels around the sun in one year ( days)
The earth’s path or orbit around the sun is not circular (it is an ellipse or elongated circle)

34. Sun
Earth
Moon Vocab Review

35. Axis
Ellipse
24 hours
365 ¼ days
Day/Night
1 year