1. Chapter 28 Minor Bodies of the Solar System
The Moon

2. The moon is a natural satellite
A satellite is a natural or artificial body that revolves around a celestial object
Sputnik, was launched by the Soviet Union the month I was born!
It was the first artificial satellite

3. Apollo program
6 spacecraft to the moon

4. July 20, 1969 Neil Armstrong set foot on the moon.
Do you know what he said?
That’s one small step for man, one giant leap for mankind.

5. Moon gravity The moon has much less mass so has much less gravity
A person weighs 1/6th the amount he weighs on Earth

6. Lunar surface Lunar comes from the Latin word luna moon
Light and dark patches visible
Light—anorthosites
Dark—maria—seas of solidified lava formed from massive meteoroid bombardment

7. Regolith
The surface of the moon is covered with a fine dust called regolith
2 causes:
Meteor bombardment
Thermal shock—expansion and contraction caused by lack of an atmosphere

8. One side of the moon always faces Earth
The pull of the Earth’s gravity during formation caused the crust on the far side to become thicker
Near side lunar crust is 60km thick
Far side up to 100 km thick

9. One Side of the Moon There is no DARK SIDE
We always see the same side because the Moon’s rotational rate matches the rate at which it revolves around the Earth.
Rotates (and revolves) once every 27.3 days.
Gravity lock between the Earth and the Moon
There is no DARK SIDE

10. So why is a lunar cycle 29.5 days?
While the moon is revolving around the Earth, Earth and the Moon are also revolving around the sun
It takes time to catch up to Earth’s movement

11. Barycenter The Earth and the moon actually revolve around each other.
Their common center of mass is called the barycenter
It is located within the Earth

12. READ PGS 725 & 732

13. Layered Crust Mantle Maybe a small iron core (layered)
No magnetic field

14. Tides
Because of the pull from the moon’s gravity on Earth's water, the water forms a bulge on the moon-ward side. This is high tide.

15. The position of the moon determines the type of tide

16. Formation of the Moon The Giant Impact Hypothesis
Formerly several main hypotheses
Now . . .
The Giant Impact Hypothesis
A Mars-sized body hit the Earth while it was still quite hot
The collision ejected chucks of mantle into orbit around Earth
This came together to form the moon

17. Other Theories of the Moon’s formation
Simultaneous creation
Fission
Capture
Collision

18. Simultaneous creation
Formed at the same time from same stuff
Problem: Earth has 3 X's more iron

19. Fission George Darwin, son of Charles,
hypothesized that the Moon and Earth were originally one body.
As it revolved and rotated it cooled and began to rotate faster
A giant bubble of still molten material pulled away and escaped

20. Capture
Formed elsewhere in the solar system and was caught as it traveled by the Earth

21. Collision
Young Earth was hit by an asteroid that knocked off a chunk and then the asteroid and chunk were caught in the gravitational field.

22. One Side of the Moon There is no DARK SIDE
We always see the same side because the Moon’s rotational rate matches the rate at which it revolves around the Earth.
Rotates (and revolves) once every 27 days.
Gravity lock between the Earth and the Moon
There is no DARK SIDE

23. Misc Factoids
Diameter about the size from San Francisco to New York City
1996 discovered ice deposits at the poles

24. Phases of the Moon
At any given moment rays of sunlight illuminate one half of the Moon's surface.
Because the moon rotates and revolves around earth we see phases--changes in shape that occur every month.

25. Study this picture page730!!!!!!!

27. Imagine you are on Earth
What do you see?
Imagine you are on Earth

28. New moon-- occurs when the Sun, moon and Earth are lined up
The new moon is the side we cannot see

29. Full moon--
we see the side that is lit up

30. Waxing--
getting bigger
right side lit up

31. Waning--
getting smaller
left side lit up

32. Crescent--
Crescent roll shape
Crescent roll shape

33. Half moon—1st quarter

34. Gibbous--
More than half is lit up
Funny name for a funny shape

35. We put these words together to describe the moon.
Full moon
New moon
Waxing gibbous
Waning crescent

36. Phase Game SUNLIGHT Dusk Midnight Noon Dawn Earth Full Moon 1st QTR
Waxing Gibbous
Waxing Crescent
New Moon
Waning Gibbous
3rd QTR
Waning Crescent
Earth
Dusk
Midnight
Noon
Dawn

37. Eclipses
The Sun is 400 times larger than the Moon in diameter, it is also 400 times farther away. So, the sun and Moon appear the same size in the sky.
This allows us to have eclipses.

38. Moon is between the sun and earth
Solar Eclipse
Only seen by a small area of Earth

39. Solar eclipse
Moon's shadow falls on the Earth

40. Only a few people under the path
Who gets to see them???
Only a few people under the path

41. The shadow has two parts, the umbra and penumbra
Umbra--darker, inner shadow
Penumbra– lighter, outer shadow

42. Lunar eclipse
Earth's shadow falls on the moon

43. Why are eclipses so rare?
5.2 tilt of the moon orbital plane The Earth and Moon have different orbital planes