1. A look at our nearest neighbor in Space!
The Moon
A look at our nearest neighbor in Space!
Free powerpoints at

2. What is the Moon? A natural satellite
One of more than 96 moons in our Solar System
The only moon of the planet Earth

3. Location, location, location!
About 384,000 km (240,000 miles) from Earth
3,468 km (2,155 miles) in diameter (about ¼ the size of Earth)

4. Theories for Origin of Moon
Fission: originally part of Earth but torn free
Problem: would have fallen back or been flung into space, not into orbit.
Fails to explain why lunar chemistry differs from Earth's
Co-Creation: formed in its present orbit
can not explain why lunar chemistry differs from Earth's
Capture: formed as a separate planet but captured by Earth
Conditions for successful capture very stringent
Impact: formed from Mega-Impact of Mars-sized planet
Computer modeling suggests SS forms 100 or so small planets, then collide to make larger objects
can explain differences in chemistry:
impact occurred after chemical differentiation in Earth; therefore, not as much iron was part of the Moon
high temperatures during impact would have vaporized the volatile and water vapor in rocks
Currently favored model

5. Birth of the Moon “Born” 4-5 billion years ago
Formed from impact of Mars-sized “planetesimal” on Earth
Debris from both objects melted together to form the Moon

6. Computer Simulation of Formation of Moon
Moon may have
formed by a
Mars-sized object
impact on Earth
Some of the material
does not fall back
onto the Earth, but
forms a satellite
of Earth

7. Cut to the Core 3 major divisions of the Lunar interior
Crust - average thickness of about 70 kilometers
Mantle
Core - radius is between 300 and 425 kilometers

8. Moon’s interior structure
crust is thicker on
non-Earth facing side
iron-rich core like Earth
asthenosphere layer: somewhat pliable “plastic” layer
solid layer just below surface – no plate tectonics
smaller planet than Earth – less internal energy, less geological activity!
moon probably had a weak magnetic field early in history
- core is now solid, so no current is generated

9. Moonquakes: Studying the Moon’s Interior
~ 3000 quakes/year
much lower intensity
than Earth: Richter
indicate that Moon’s
interior is more rigid than
Earth’s (some ‘plasticity’)
Seismometer placed on Moon by lunar astronauts

10. The Moon’s Surface No atmosphere No liquid water Extreme temperatures
Daytime = 130C (265°F)
Nighttime = -190C (-310 F)
1/6 Earth’s gravity

11. Lunar Features - Highlands
Mountains up to 7500 m (25,000 ft) tall
Rilles (trenchlike valleys)

12. Lunar Features - Craters
Up to 2500 km (1,553 miles) across
Most formed by meteorite impact on the Moon
Some formed by volcanic action inside the Moon

13. Lunar Geological Features
Craters
~30,000 visible with small telescopes from Earth
millions visible from lunar orbiting satellites
origin: interplanetary debris
sizes: largest 100’s km
across a result of fast
moving impact rocks
of only a few km’s across!
large craters often
produce “central peak”
craters
Clavius Crater
diameter = 232 km
depth of 16,000 feet

14. Lunar Features - Maria
Originally thought to be “seas” by early astronomers
Darkest parts of lunar landscape
Filled by lava after crash of huge meteorites on lunar surface 3-4 billion years ago
Mostly basalt rock

15. Limb
Terminator

16. Craters
Can you see the rays?
Maria
Does this photo show us a limb or terminator line?

17. Color-coded images illustrate surface geography
Galileo data – flyby in 1989
blue – lowland marias
red - highlands

18. Movements of the Moon
Revolution – Moon orbits the Earth every 271/3 days
The moon rises in the east and sets in the west
The moon rises and sets 50 minutes later each day
Rotation – Moon turns on its axis every 27 days
Same side of Moon always faces Earth

19. Moon Rocks: Sampling the Surface of the Moon
surface material: “regolith” –
pulverized by constant impacts
~2500 samples brought back
by astronauts; ~850 lbs total!!
all rocks are IGNEOUS (i.e.,
from molten processes)
totally dry rocks (no water)
all rocks older than 3 Byr

20. Far Side of the Moon First seen by Luna 3 Russian space probe in 1959
Surface features different from near side
More craters
Very few maria
Thicker crust

21. It’s Just a Phase Moonlight is reflected sunlight
Half the moon’s surface is always reflecting light
From Earth we see different amounts of the Moon’s lit surface
The amount seen is called a “phase”

22. Waxing and Waning New moon Waxing Crescent moon First Quarter moon
Waxing Gibbous moon
Full moon
Waning Gibbous moon
Third Quarter moon
Waning Crescent moon

23. FOUR MAIN SHAPES
FULL
Four Basic Shapes
CRESCENT
GIBBOUS
QUARTER

25. Rising/Meridian/Setting Times
Phase
Rising
Meridian
Setting
New
6 am
Noon
6 pm
Waxing Crescent
9 am
3 pm
9 pm
First Quarter
Midnight
3 am
Full
Waning Gibbous
Third Quarter
Waning Crescent
*Assuming the moon is always on the celestial equator and above the horizon 12 hours per day.

26. Earth
Plane of earth’s orbit
Moon
Plane of lunar orbit
Moon

27. Lunar Eclipses
Moon moves into Earth’s shadow – this shadow darkens the Moon
Umbra
Penumbra
About 2-3 per year
Last up to 4 hours

28. Solar Eclipses Moon moves between Earth and Sun
Moon casts a shadow on part of the Earth
Total eclipses rare – only once every 360 years from one location!

29. The Tides Tides caused by pull of Moon’s gravity on Earth High tide –
Side facing Moon and side away from Moon
Every 12 hours, 25 ½ minutes
Low tide –
On sides of Earth

30. Exploring the Moon 1950s to 1960s - probes
Neil Armstrong First man on the Moon – July 20, 1969
Six Apollo missions ( )
382 kg (842 lbs) rocks
12 Americans have walked on the moon

40. When will we return?

41. Ice on the Moon?
1994 – Clementine probe
1998 – Lunar Prospector

42. Moon base of the future?
What would you need to live there?

45. The Lunar Challenge!

46. Name this phase!
Full Moon
What time does this phase rise and set?

47. Name these features.
Craters
Maria
Name these features.

48. Does this image show us the near side or far side of the moon?
How can you tell?

49. Is this line the limb or terminator?

50. Name this phase!
First Quarter

51. Name this phase!
Waxing Crescent

52. Does this image show the near side or the far side of the moon?

53. Name this phase!
Waning Gibbous

54. Name this phase!
Third Quarter

55. From what direction does the moon rise?
The East

56. Name this phase!
Waxing Gibbous

57. Name this phase!
Waning Crescent

58. What might be happening in this image?
Lunar Eclipse

59. Is this line the limb or the terminator?

60. Name this phase!
Look closely!
Waxing Gibbous

61. The Far Side and the Dark Side of the moon are the same thing.
True or False:
The Far Side and the Dark Side of the moon are the same thing.
False!

62. Name this phase!
Full Moon

63. Name this phase!
New Moon

64. Does the moon rise or set in the west?
It sets in the west.

65. Name this phase!
Waning Gibbous

66. Name this phase!
Waning Crescent

67. Name this phase!
Waning Gibbous