1. Warmup 1/7/12 Put the following in the correct order:
Air expands due to lower pressure
Warm air rises
Condensation occurs and a cloud forms
Air cools until it reaches the dewpoint
Imagine you have decided to build a house on the Outerbanks of NC. Considering that your house is likely to experience a hurricane, what could you do to prevent damage from storm surge?

2. Earth’s Moon
1.1.2 a Describe daily changes due to rotation, seasonal changes due to the tilt and revolution of the Earth, and tidal impact due to the gravitational interaction between the Earth and moon.
1.1.2b Develop a cause and effect model for the shape of the Earth explaining why the circumference around the equator is larger than that around the poles.

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
Scientists think the moon formed after a large object, about the size of a planet, hit Earth.
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.

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. 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.
Light from the Sun
Waning Crescent
Waxing Crescent
New Moon
Full Moon
Waning Gibbous
Waxing Gibbous
Last Quarter
First Quarter
Phases of the Moon

7. 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

8. 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

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

10. 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
Skip for today
Midnight
Midnight
6 pm

11. 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

12. 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.

13. “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

14. 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

15. 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

16. 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.

17. 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.

18. 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.
Uniform water level
Moon
Moon’s orbit
Low tide
Direct high tide
Indirect high tide

19. 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.
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.

20. 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

21. 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

22. Tides Perigee: The point closest to Earth in the moon’s orbit.
Apogee: The point farthest to Earth in the moon’s orbit.
Same gravitational force makes the Earth wider in the middle than at it’s poles (aka sphere)

24. 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.