1. The moon

2. Good morning 
1. Get your notebook and label Assignment 5: The Moon in your table of contents.
2. Go to the next available page behind Assignment 4, and label it with Assignment 5: The Moon.
3. Find a partner and discuss the following questions, and be ready to answer them when class begins.
We have modeled the motion of the Earth-Sun-Moon. How do we know that those motions exist?
What are some patterns we can observe that indicate the motions of the Earth-Sun-Moon?

3. Satellites – natural or artificial bodies that revolve around larger bodies such as planets.

4. Except for Mercury and Venus, all of the planets have natural satellites called moons.
Earth’s moon is a satellite called Luna.

5. The lunar rocks brought back during the Apollo missions were found to be about 4.6 billion years old.
Because these rocks have hardly changed since they formed, scientists know the solar system itself is about 4.6 billion years old.

6. Before scientists had rock samples from the moon, there were three popular explanations for the moon’s formation:

7. 1. The moon was a separate body captured by Earth’s gravity.

8. 2. The moon formed at the same time and from the same materials as Earth.

9. 3. The newly formed Earth was spinning so fast that a piece flew of and became the moon.

10. When rocks brought back from the moon were studied, scientists found that the composition of the moon was similar to that of Earth’s mantle.
This evidence from the lunar rock samples supported the third explanation for the moon’s formation.

11. The current theory of the formation of the moon is that a large, Mars-sized object collided with Earth while Earth was still forming.
The collision was so violent that part of Earth’s mantle was blasted into orbit around Earth to form the moon.

12. From Earth, one of the most noticeable aspects of the moon is its continually changing appearance.

13. These different appearances of the moon result from its changing position relative to Earth and the Sun.
The different appearances of the moon due to its changing position are called phases.

14. Waxing and Waning
When the moon is waxing, the sunlit fraction that we can see from Earth is getting larger.

15. When the moon is waning, the sunlit fraction is getting smaller.

16. Even as the phases of the moon change, the total amount of sunlight that the moon gets remains the same.
The positions of the moon, sun, and Earth determine which phase the moon is in.

17. Half the moon is always in sunlight, just as half the Earth is always in sunlight.
Because the moon’s period of rotation is the same as the period of revolution, on Earth you always see the same side of the moon.

18. New moon – The moon’s disk facing us is dark because the moon is between the sun and the Earth.

19. Waxing crescent moon – A little part of the moon’s right side is in sunlight.

20. First quarter moon – the right half of the moon’s disk is in sunlight.

21. Waxing gibbous moon – About ¾ of the right side of the moon’s disk is in sunlight.

22. Full moon – The moon’s entire disk is in sunlight because the Earth is between the sun and the moon.

23. Waning gibbous moon – About ¾ of the left side of the moon’s disk is in sunlight.

24. Last quarter moon – The left half of the moon’s disk is in sunlight.

25. Waning crescent moon – A little part of the moon’s left side is in sunlight.

26. Moon Phases Activity

27. Write and Answer the following questions in your notebook:
1. What is the first phase of the moon called?
2. What is the shape of a crescent moon?
3. Which phase is larger, the crescent or the gibbous?
4. Why can’t we see a new moon?
5. How does the pattern of the lunar phases help us understand the movement of the stars in the Milky Way galaxy?