1. Earth’s Moon

2. Earth’s Moon
Origin and Properties of the Moon
The Moon’s Motions

3. The Moon Facts about the Moon…
We see the moon changes its appearances and position in the sky with approximately 30-day cycle.
Unlike the stars, Moon can also be seen during the day.
We also see that the Moon is always involved in eclipses, and
Its position seems to be well correlated with the tide of the ocean.
Understanding the motion of the Moon with respect to the Sun and the Earth will explain these phenomena.
The moon revolves around the earth with a period of about 29 ½ days ~ one month!

4. Origin and Properties of the Moon
Earth’s Moon
Origin and Properties of the Moon
VOCABULARY
Scientists think the moon formed after a large object, about the size of a planet, hit Earth.
crater
micrometeoroid
1. Earth is hit off-center by a planet-sized object.
2. The impact heats and deforms both bodies. Some rocky debris remains in orbit around Earth.
3. The debris ring, made of rock from the outer layer of both objects, gradually coalesces, forming the moon.
maria
mascons
rille
ray
regolith

5. Much of the material broken away from the earth goes into orbit.
The moon reassembles in this orbit - it takes about a month of violent collisions. 
Earth is speeded up in rotation as a result of the collision.
This theory is consistent with:
1.) composition of lunar rocks, which is similar to the composition of the crust of the earth;
2.) evidence that the moon had a molten surface for 200 million years; and
3.) the lack of magnetic field for the moon, which together with its low density implies it has very little iron in its core.
Impact theory

6. Earth’s Moon
The same side of the moon always faces Earth. Dark areas called maria are great basins and level plains on the moon. They are younger than the lighter lunar highlands. Lunar highland rocks are older than mare rocks.
Mare
Highland
Maria: Extensive dark areas on the moon that represent great basins and level plains.

7. Earth’s Moon
Most lunar craters were caused by the impact of meteoroids; rays of shattered rock and dust were splashed out by the impacts.
Regolith is the loose rock material covering the moon’s surface. It is formed as micrometeoroids smash into and erode the moon’s surface.
Crater: A bowl-shaped depression on the surface of a moon or a planet, usually caused by the impact of a meteorite.
Micrometeoroid: Tiny rock fragment no larger than sand grains that travels through space.
Lunar rocks have textures similar to Earth rocks but differ in composition.

11. Earth’s Moon
Rille: A trenchlike valley running through the bedrock of lunar maria, believed to have formed after the cave-in of the roof of a tunnel that had transported lava.
Ray: A bright streak of shattered rock and dust that radiates from a lunar crater.

12. The Moon’s Motions Earth’s Moon
The moon’s orbit is tilted 5 degrees relative to the plane of Earth’s orbit. The moon’s movement around Earth causes it to rise later each day and to go through phases.
VOCABULARY
phases
waxing
waning
gibbous
Light from the Sun
Waning Crescent
Waxing Crescent
New Moon
Full Moon
Waning Gibbous
Waxing Gibbous
Last Quarter
First Quarter
Phases of the Moon
umbra
penumbra
lunar eclipse
solar eclipse

13. Lunar Phases Sunlight illuminates half of the Moon
it’s a ball and the Sun is shining on it from one direction
This causes the “phases” of the Moon
Waxing Moon – increasing from day to day
Waning Moon – decreasing from day to day

14. Lunar Phases (cont) New Moon Full Moon
Waxing Crescent Moon
Waxing Half Moon
Waxing Gibbous Moon
Full Moon
Waning Gibbous Moon
Waning Half Moon
Waning Crescent Moon …
New Moon
The Moon is on the same part of the sky as the Sun and rises and sets with the Sun
Full Moon
The Moon is in the opposite side of the sky as the Sun and rises when the Sun sets and sets when the Sun rises

15. The Phase of the Moon
The phase of the Moon depends on the relative position between the Sun, the Earth, and the Moon…

16. The time the Moon rises and sets is correlated to its phase
Moonrise/Moonset
The time the Moon rises and sets is correlated to its phase
Phase of the Moon
Rise
Zenith
Set
New Moon
6 am
6 pm
Waxing Half Moon
Full Moon
Waning Half Moon
Noon
Noon
Noon
Midnight
Midnight
Midnight
6 pm

17. Why do we Always See the Same Side of the Moon?
The rotation period of the Moon with respect to the universe is exactly the same as the rotation period of the Moon around the Earth.
Is this a coincidence?
No!  It’s due to Tidal Locking

18. Tidal Locking
A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body.
The Moons orbital period is 27.3 days. It also rotates once on its axis in 27.3 days (synchronous rotation) resulting in Tidal Locking.

19. “Dark Side” of the Moon The Moon doesn’t have a “dark side”
Everywhere on the Moon, the Sun rises and sets once per month
It has a side which faces away from us
During a New Moon, the far side is completely illuminated

20. The Moon’s Motions
A lunar eclipse occurs when Earth passes between the sun and the moon, and the moon is within Earth’s shadow.
Sun
Earth
Penumbra
Moon
Umbra
lunar eclipse
A solar eclipse occurs when the moon passes between the sun and Earth, and the moon’s shadow falls on Earth.
Total Solar Eclipse
Sun
Earth
Moon
solar eclipse

21. Eclipses
Eclipses occur when the Sun, the Earth and the Moon all lie along a straight line
They must line up in all 3 dimensions + time
the Moon’s orbit is tilted 5o with respect to the ecliptic, so there are only two times a year when the paths overlap

22. Solar and Lunar Eclipses
The total or partial obscuring of one celestial body by another…
The obscuration can be either
One celestial body blocking the view to the other:
Solar eclipse---Moon blocking Earth’s view to the Sun…
One celestial body is in the shadow of another:
Lunar eclipse---Moon is in the shadow of the Earth…
Lunar eclipse image from

23. Lunar Eclipse
Umbra: The darkest part of the shadow cast by the moon or by Earth.
Penumbra: The area of partial shadow surrounding the darkest part of the shadow of the Earth or moon.
Lunar eclipses can only occur during a full moon. The maximum time a lunar eclipse can last is 3 hours and 40 minutes.

24. Solar Eclipse
Solar eclipses can only occur during a new moon. The maximum time for a total solar eclipse is 7 minutes and 40 seconds.
Solar eclipses are visible in a narrow path a maximum of 167 miles wide (269km.)

25. Total Solar Eclipse of 21 June 2001 from Zimbabwe
See Richard Monk’s
webpage on eclipses:
astronomy/IAU_eclipses/
Bailey’s Beads
Solar Corona
“Diamond Ring”

26. Solar Eclipse Forecast
Solar eclipses from 2004 to 2030
Knowing the orbit of the Earth and the Moon, we can now calculate the time and path of solar eclipses with great accuracy.

27. Eclipses: Summary The parties involved: Sun, Moon, and Earth
Motion of the Moon around Earth:
29 ½ day revolution of the Moon around the Sun
Tilt (~5º) of the lunar orbit (around the Earth) w.r.t. the Ecliptic plane (Earth’s orbital plane around the Sun)
The precession of the lunar orbit w.r.t. Earth-Sun direction
Solar eclipse happens when the Moon is between the Earth and the Sun.
The size and distance of the Moon need to be just right for us to see total eclipse.
The changing distance between the Earth and the Moon explains the occurrences of the total and ring solar eclipses.
The changing distance between the Earth and the Sun, and the Earth and the Moon explains the difference in the duration of the solar eclipses.
Lunar eclipse happens when Earth is between the Moon and the Sun.

28. Eclipse facts Lunar eclipses can only occur during a full moon.
Solar eclipses can only occur during a new moon.
A Solar eclipse always occurs two weeks before or after a lunar eclipse.
Eclipses very often occur in threes, alternating lunar, solar and lunar.

29. Eclipse facts
The maximum time a lunar eclipse can last is 3 hours and 40 minutes.
The longest time the Moon can stay in totality is 1 hour 40 minutes.
The maximum time for a total solar eclipse is 7 minutes and 40 seconds.
The maximum time for an annular solar eclipse is 12 minutes 24 seconds.
Lunar eclipses can occur up to 3 times a year.

30. Eclipse facts
Solar eclipses can occur at least 2 and no more than 5 times a year.
Lunar eclipses are visible over an entire hemisphere.
Solar eclipses are visible in a narrow path a maximum of 167 miles wide (269km.)
At any geographic position on the Earth, a total solar eclipse occur an average of once every 360 years.

31. Eclipse facts
The cycle of eclipses repeats every 18.6 years called the saros.
The eclipse shadow moves at 2,000 mph at the Earth's poles and 1,000 mph at the Earth's equator.

32. The Moving Ocean
Tides
The twice-daily rise and fall of Earth’s oceans— known as the tide—is a result of gravitational pulls from the moon and the sun.
VOCABULARY
tides
perigee
Uniform water level
Moon
Moon’s orbit
apogee
Low tide
Direct high tide
Indirect high tide

33. The Moving Ocean
Tides
VOCABULARY
The twice-daily rise and fall of Earth’s oceans— known as the tide—is a result of gravitational pulls from the moon and the sun.
tides
perigee
apogee
Tides reach different levels depending on Earth’s location in relation to the moon and sun.
• High tides are higher and low tides are lower when the moon, sun, and Earth are aligned.
• High tides are not as high and low tides are not as low as usual when the moon and sun are not in line with Earth.

34. Higher high tides and lower low tides
Spring Tides
The gravitational affects of the moon and sun combine to influence the flow of the oceans on Earth.
Moon
Moon
Moon
Earth
Phase of the moon?
Phase of the moon?
Phase of the moon?
New Moon
New Moon
Full Moon
Higher high tides and lower low tides

35. Lowest high tides and highest low tides
Neap Tides
The gravitational affects of the moon and sun fight each other with their influence on the flow of the oceans on Earth.
Moon
Phase of the moon?
Moon
Phase of the moon?
Third Quarter
Third Quarter
Earth
Phase of the moon?
Moon
First Quarter
Lowest high tides and highest low tides

36. Tides Perigee: The point closest to Earth in the moon’s orbit.
Apogee: The point farthest to Earth in the moon’s orbit.

40. We see a permanent "near" and "far side" of the Moon.
Tides & Consequences
This little tidal behavior goes both ways! The Earth rises tides on the Moon.
The Earth "brakes" the Moon's rotation AND the braking is complete! Synchronous Rotation of the Moon and its orbital period! (27.3 days!)
We see a permanent "near" and "far side" of the Moon.
Moon also brakes the Earth's Rotation
The length of the "day" is increasing!
From fossil reef corals of about 4´108 years old - daily growth/annual growth  400 days/year ~ 22 hours a day!
Day is increasing about seconds/century.
Moon's orbit is growing because of all of this interaction.
Therefore, the day is getting longer, Moon looks smaller, and tides are weakening.

41. The Lunar Program and Flagstaff

51. Two members of the prime crew of the Apollo 17 lunar landing mission participate in lunar surface extravehicular activity simulation training at the Kennedy Space Center, Florida.

52. “Genesis Rock" returned by the Apollo 15 lunar mission

53. During the Apollo 12 mission in 1969, commander Pete Conrad retrieves equipment from the Surveyor 3 probe, which landed on the moon three years earlier. This picture, taken by astronaut Alan Bean, shows Apollo 12's lunar module in the far distance.

57. Apollo 17 astronaut Harrison Schmitt standing next to boulder at Taurus-Littrow during third extravehicular activity (EVA-3).

58. This photo was taken by Apollo 17 commander Eugene Cernan
This photo was taken by Apollo 17 commander Eugene Cernan. It is of lunar module pilot Harrison Schmitt standing in front of a large split boulder on the Moon. Apollo 17 was the last of the Apollo Moon landing missions.

60. I. Origin and Properties of the Moon
Earth’s Moon
VOCABULARY
I. Origin and Properties of the Moon
astronomy
A. Origin of the Moon
meteoroid
1. Development of the Moon
crater
2. The Moon Today
micrometeoroid
B. Properties and Features of the Moon
maria
1. Lunar Maria
mascons
2. Lunar Highlands
rille
3. Lunar Craters and Rays
ray
4. Lunar Soil
regolith

61. Earth’s Moon II. The Moon’s Motions A. The Moon’s Orbit
VOCABULARY
II. The Moon’s Motions
phases
A. The Moon’s Orbit
waxing
B. The Moon’s Phases
waning
C. Lunar Eclipses
gibbous
D. Solar Eclipses
umbra
penumbra
lunar eclipse
solar eclipse

62. The Moving Ocean III. Tides A. The Moon and Tides
VOCABULARY
III. Tides
tides
A. The Moon and Tides
perigee
B. The Sun’s Effect on Tides
apogee
C. Tidal Range