Phases of the Moon

1. Phases of the Moon

2. The moon goes through phases because a. the Earth's shadow falls on different parts of the moon at different times. b. the moon is somewhat flattened and disk-like, and appears more or less round depending on the precise angle from which we see it. c. sunlight reflected from the Earth lights up the full moon but is less effective when the moon is lower in the sky, at which time we see crescents. d. we see only part of the lit-up face of the moon depending on its position relative to us and the Sun.

3. The moon goes through phases because a. the Earth's shadow falls on different parts of the moon at different times. b. the moon is somewhat flattened and disk-like, and appears more or less round depending on the precise angle from which we see it. c. sunlight reflected from the Earth lights up the full moon but is less effective when the moon is lower in the sky, at which time we see crescents. d. we see only part of the lit-up face of the moon depending on its position relative to us and the Sun.

4. It’s the geometry that determines phases: • Half of the moon is always lit. • As you view the moon from different directions (relative to the Sun) its appearance changes.

5. Crescent Moon

6. 1st Quarter Moon

7. Gibbous Moon

8. FULL MOON

9. QUESTION: • What time does the moon rise in the evening?

10. Lunar Cycle • If the moon is just rising tonight at 6 pm, in how many days will it again be just rising at 6 pm? • 29.5 days (lunar month) • Will it rise earlier or later tomorrow night? • later • At about what time will it be just rising tomorrow night? • about 6:50 pm

11. View looking down from Polaris(observer on the equator) Which way does the Earth spin? If the moon is just rising, where is it? Where will the observer be in 6 hours?

12. Midnight Where is the moon? When will the moon set?

13. 6 am What happens in another 12 hours?

14. 6 pm But the moon shouldn’t rise for another hour!! Where will the observer be at 7?

15. 7 pm But the moon shouldn’t rise for another hour!! Where will the observer be at 7? So where is the moon at 7?

16. 1 day 7 pm But the moon shouldn’t rise for another hour!! Where will the observer be at 7? So where is the moon at 7? WAIT A MINUTE! How long for the moon to go around once? 27 1/4 days(sidereal month)

17. Where will Earth be in 27 1/4 days? new moon

18. Where will Earth be in 27 1/4 days? new moon takes an extra 2 1/4 days (total of 29.5 days)

20. Solar Eclipse • Solar Eclipse – occurs when the Moon passes between the Earth and Sun and the Moon obscures Earth's view of the Sun totally or partially. This configuration can only occur during a new moon.

22. Lunar Eclipse • When the Moon passes through the Earth's shadow. Can happen during a full moon.