1. Moon Phases & Eclipses
What patterns, motions, and events do we notice in the sky?
What theories can we create to explain them?
How can these theories be tested?

2. The last LUNAR eclipse YOU might have seen…
September 28, 2015

3. The next LUNAR eclipse YOU can see…
March 23, 2016

4. The last TOTAL SOLAR eclipse YOU could have seen…
Monday morning,
21 August 2017

5. The “nearby” TOTAL SOLAR eclipse YOU might have seen…
August

7. The next TOTAL SOLAR eclipse YOU hopefully will see!…
August

8. A really “nearby” TOTAL SOLAR eclipse YOU might see…
August
Chabot College

9. Observations of the Moon
Sequence of phases every “moonth”
We always see the same “face”

10. Observations of the Moon
Occasionally turns dark gray & even red!
Can seem bigger next to the horizon!

11. Phases repeat ~30 days A “moonth” of time
Tied to religious calendars around the globe
Ramadan
Chinese New Year
Easter
Rosh Hashanah
Gudi Padwa & Vasant Panchami

12. Observations of the Moon
Sequence of repeated phases over ~ “moonth”
Sunlight reflecting off Moon that is visible to us
NOT Earth’s shadow!!

13. Observations of the Moon
IS the phase the same on the same day around the world?
Do people in London see the same phase as we do in Hayward?

14. Observations of the Moon
IS the phase the same on the same day around the world?
Most people would say…… NO!
They are wrong!
Compare times
For Earth to rotate: hours
For the Moon to move & change phase: days

15. Observations of the Moon
Do people in both hemispheres see the same view?
Does an observer at Chabot see the same thing as someone in Santiago, Chile?
Most people would say…… er…YES?
They are wrong!

16. Phases are “reversed” in Southern Hemisphere!
Same side of moon is still lit by the sun
Observation from “down under” reverses view.

17. Northern Hemisphere Phases!
Southern Hemisphere Phases!

18. Seeing the moon from different places on Earth!

19. Seeing the moon from different places on Earth!
Northern Hemisphere
Southern Hemisphere

20. The Moon Illusion!

21. The Moon Illusion!

22. What theories can we develop?
WHY does the moon seem larger?
Because it IS larger?
Because it is an illusion
We see horizon different than zenith?
We don’t have a “reference” for Moon when it’s higher in the sky?
How can you TEST these hypotheses?

23. The Moon DOES vary in distance….
The Moon Illusion!
The Moon DOES vary in distance….

24. ….but not over a few hours!
The Moon Illusion!
….but not over a few hours!

25. The Moon Illusion!
Perhaps… we don’t see the sky as symmetric – the horizon is farther away than the sky above us?

26. Solar Eclipses Occur at NEW moon phase
While partial, a “bite” out of the Sun
Last 1+ hours
IF total…
Sky goes dark for a few minutes
See planets and stars near the sun
See Sun’s corona and chromosphere

27. Shadow of
the moon
covers small
oval on Earth

28. FIGURE 1-26 A Total Eclipse of the Sun
During a total solar eclipse, the Moon completely covers the
Sun’s disk, and the solar corona can be photographed.
This halo of hot gases extends for millions
of kilometers into space. This gorgeous image is a composite
of several taken in Chisamba, Zambia, during the June 21,
2001, solar eclipse. (F. Espenak)

29. Corona
Chromosphere

31. Annual Solar Eclipse Time-lapse series of photos What time of day?
How long did this take?
Hint: Northern Hemisphere!

32. Lunar Eclipses Occur at FULL moon phase The Moon looks full, but dim
The Earth’s curved shadow falls across the moon
Last 2+ hours
IF total…
Moon can look red for an hour

33. At the start of a lunar eclipse, you can see the Earth’s Shape through its shadow…

35. Lunar Eclipse Time-Lapse
Note the curved shadow of the Earth across the moon.

36. Predicting Eclipses Eclipse “seasons” About twice a year
Always at least (2) eclipses
One of each (lunar + solar)
About 2 weeks apart
Pattern repeats about 18 years for location and type

37. Eclipse “Seasons”

38. The next total LUNAR eclipse YOU can see…
Monday night,
21 January 2019

39. The next total LUNAR eclipse