Copyright © 2010 Pearson Education, Inc. Lecture Outline Chapter 5 Earth and Its Moon

Copyright © 2010 Pearson Education, Inc.

Lecture Outline

Chapter 5 Earth and Its

Moon


An amazing fact

• We are here, after 13.7 billion years, as the first century of any object or being (check this) able to contemplate and reflect and be self aware.

• We are just stuff from the universe, dust and ice, that assembled in a strange way, and is now able to think.

• We are the universe looking at itself.


Chapter 5Earth and Its Moon

Start with what we know best

The only two bodies in the universe that humans have touched!

Alien abductions not included.


Units of Chapter 5

Earth and the Moon in Bulk

The Tides

Atmospheres

Interiors

Surface Activity on Earth

The Surface of the Moon

Magnetospheres

History of the Earth–Moon System

Summary of Chapter 5


First, let’s explore gravity• Look at Moons of Jupiter Lab in folder

• Understand how data from a telescope can tell us about moons

• And can even tell us about mass of the planet

• P:\Rod on P\school files\physics\Astronomy\moons of jupiter lab from jim lund\Moons of Jupiter lab.pptx

• P:\Rod on P\school files\physics\Astronomy\moons of jupiter lab from jim lund\Moons of Jupiter Lab 2 up.pdf


5.1 Earth and the Moon in Bulk

Density of liquid water = 1000kg/m3

Density of iron: 7.9 Density of granite: 2.8


Tides are due to gravitational force on Earth from Moon – force on near side of Earth is greater than force on far side. Water can flow freely in response.

5.2 The Tides

Can we see the swing in solar system simulator?


The Sun has less effect, but it does modify the lunar tides.

5.2 The Tides

Have you heard of high-high and low-high etc?


Tides tend to exert a “drag” force on Earth, slowing its rotation.

This will continue until Earth rotates synchronously with the Moon, so that the same side of Earth always points toward the Moon.

5.2 The Tides


5.2 The Tides

This has already happened with the Moon, whose near side is always toward Earth.


Quiz for friday• For each phase, name it and describe what time of night you’d

see it (early evening, all night, or before sunrise).

• 1. 2. 3.

• 4. 5. 6.


Liz found this

http://www.youtube.com/watch?v=qGwRp38-gzE


Influence of atmospheres on a planet or a moon

1. Erosion

2. Protection from solar radiation and ions

3. Temperature

4. Chemistry

5. Life

6. Others?____albedo, asthetics______


• The blue curve shows the temperature at each altitude.

• Troposphere is where convection takes place – responsible for weather.

5.3 Atmospheres, major influence on a planet


Convection depends on warming of ground by the Sun.

5.3 Atmospheres


Ionosphere is ionized by solar radiation, and is good conductor.

Reflects radio waves in the AM range, but transparent to FM and TV.

Ozone layer is located in the Stratosphere; absorbs ultraviolet radiation.

5.3 Atmospheres


Chlorofluorocarbons (CFCs) have been damaging the ozone layer, resulting in ozone hole.

Discovery 5-1: Earth’s Growing Ozone Hole


Surface heating:

• Sunlight that is not reflected is absorbed by Earth’s surface, warming it.

• Surface re-radiates as infrared thermal radiation.

• Atmosphere absorbs some infrared, causing further heating.

5.3 Atmospheres


This is known as the greenhouse effect. We like it, otherwise the water would all be frozen!

5.3 Atmospheres

The atmosphere is transparent to visible light (DUH!).Visible hits the ground, is absorbed, and warms the ground. Energy radiates away from the ground in the infrared.But the atmosphere is only partially transparent to infrared. So heat is trapped in the atmosphere, and warms it. Why is the

balance changing?


Dec 5: Discovery 5-2: The Greenhouse Effect and Global Warming

There is scientific agreement that Earth is getting warmer. The cause of this warming is a subject of intense debate; it is related to the corresponding increase in atmospheric carbon dioxide.


Moon’s atmosphere

• Where is it?

• So what is different about the moon?– Wide night-day temperature range: below

freezing to above boiling – No erosion– No kite flying

• So why is water ice under the moon’s surface at the poles?


A quiz question…

1. In what ways are atmospheres …change agents? stabilizing agents?

2. Identify and describe the 3 effects that give rise to tides at the coast.



To be in my class:1. Have your text open

2. Have your notebook open

3. Have a pen in your hand

4. Write some notes

5. Ask at least one question

6. If you don’t care, act as if you care


Seismic waves: our only (?) tool to probe into the interior (tapping on the wall of earth)

• Earthquakes produce both pressure and shear waves.

• Pressure waves will travel through both liquids and solids.

• Shear waves will not travel through liquids, as liquids do not resist shear forces.

• Wave speed depends on density of material.

Name 1 other way we learn about interiors.It comes up to the surface: volcano, sea vents

5.4 Interiors, the structure of the earth or moon


5.4 Interiors

The pressure wave is a longitudinal wave, whereas the shear wave is a transverse wave. A shear wave cannot propagate within a liquid.


Can use pattern of reflections during earthquakes to deduce interior structure of Earth.

5.4 Interiors

How do they measure these waves?


Currently accepted model

5.4 Interiors


Mantle is much less dense than core.

Mantle is rocky; core is metallic, consisting of iron and nickel.

Outer core is liquid; inner core is solid, due to pressure.

Volcanic lava comes from mantle, allows analysis of composition.

5.4 Interiors


The moon’s interior is like the earth’s

Whe

re d

id th

e

moo

n co

me

from

?

The moon has

“earth”quakes, or

moonquakes, or

quakes.


Models of the sky:identify a few……

1. Globe

2. Celestial sphere clear plastic

3. Sun-earth-moon orrery

4. Stellarium

5. Solar walk

6. Star walk• Individually, prepare a 3 minute demo that

teaches us something relevant


Continental drift: Earth’s entire surface is covered with crustal plates, which can move independently.At plate boundaries, earthquakes and volcanoes can occur.

5.5 Surface Activity on Earth


Plates moving away from each other create rifts.

5.5 Surface Activity on Earth

If we follow the continental drift backward, the continents merge into one, called Pangaea.

Land of enchantment


5.5 Surface Activity on the Moon

Outer crust is too thick, mantle is too solid.So where do moonquakes come from?

noneTidal forces, morning heating of cold crust, meteorites, and slumping of younger crater walls


The Moon has large dark flat areas, due to lava flow, called maria (early observers thought they were oceans).

6 dec: 5.6 The Surface of the Moon


The far side of the Moon has few maria.

5.6 The Surface of the Moon


Crater formation: Meteoroid strikes the Moon, ejecting material; explosion ejects more material, leaving a crater.



• Craters are typically about 10 times as wide as the meteoroid creating them, and twice as deep.

• Rock is pulverized to a much greater depth.

• Most lunar craters date to at least 3.9 billion years ago; much less bombardment since then.



Very large and very small lunar craters




Regolith: Thick layer of dust left by meteorite impacts

The Moon is still being bombarded, especially by very small “micrometeoroids”; softens features.

Do we have earthquake data of the moon?


5.7 Magnetospheres

The magnetosphere is the region around Earth where charged particles from the solar wind are trapped.


5.7 Magnetospheres

These charged particles are trapped in areas called the Van Allen belts, where they spiral around the magnetic field lines.


5.7 Magnetospheres

Near the poles, the Van Allen belts intersect the atmosphere. The charged particles can escape; when they do, they create glowing light called an aurora.



Northern lights from ISS:http://www.youtube.com/watch?v=pNhei4BPf-YAnd from the groundhttp://www.youtube.com/watch?v=FcfWsj9OnsI


How to explain with sketch


Current theory of the Moon’s origin: glancing impact of Mars-sized body on the still-liquid Earth caused enough material, mostly from the mantle, to be ejected to form the Moon.Computer model

5.8 History of the Earth–Moon System


5.8 History of the Earth–Moon System

Four billion years ago, the Moon had many craters but no maria. By three billion years ago, the maria had formed. Now, they also are covered with craters.



Summary of Chapter 5

• Earth’s structure, from inside out: Core, mantle, crust, hydrosphere, atmosphere, magnetosphere

•Tides are caused by gravitational effects of Moon and Sun.

• Atmosphere is mostly nitrogen and oxygen; thins rapidly with increasing altitude.

• Greenhouse effect keeps Earth warmer than it would otherwise be.


Summary of Chapter 5, cont.

• Can study interior by studying seismic waves.

• Crust is made of plates that move independently.

• Movement at plate boundaries can cause earthquakes, volcanic activity, mountain ranges, and rifts.

• New crust formed at rifts shows evidence of magnetic field reversals.

• Earth’s magnetic field traps charged particles from solar wind.



• Main surface features on Moon: maria, highlands

• Heavily cratered

• No atmosphere and large day–night temperature excursions

• Tidal interactions responsible for synchronicity of Moon’s orbit; tidal locking

•Moon phases



• The Moon’s surface has both rocky and dusty material.

• There is evidence for volcanic activity.

• The Moon apparently formed as a result of a large object colliding with Earth.


Videos of solar windhttp://dsc.discovery.com/videos/how-the-universe-works-solar-winds.html

http://www.bbc.co.uk/science/space/solarsystem/solar_system_highlights/aurora_(astronomy)#p005xg9b


Dec 7.It was on this day in 1972 that astronauts on the Apollo 17 spacecraft took a famous photograph of Earth, a photo that came to be known as "The Blue Marble." Photographs of Earth from space were relatively new. The photograph captured on this day thirty-nine years ago was the first clear image of the Earth, because the sun was at the astronauts' back, and so the planet appears lit up and you can distinctly see blue, white, brown, even green. It was taken 2 hours after the craft left earth orbit on it’s way to the moon. It became a symbol of the environmental movement of the 1970s, and it's the image that gets put on flags, T-shirts, bumper stickers, and posters. The crew of Apollo 17 was about 28,000 miles away from Earth when they took the Blue Marble photo. It was the last time that astronauts, not robots, were on a lunar mission — since then, no people have gotten far enough away from Earth to take a photo like it.



Earthrise. The most famous photo of earth, taken by Apollo 8 crew on Christmas Eve, 1968


The Apollo Program• http://www.youtube.com/watch?v=89GUtdnyEA0• https://www.youtube.com/watch?v=awyuMF9rYhQ and

https://www.youtube.com/watch?v=CdQFZRJhkCk 9 min from Mercury through Apollo, pretty good.

• Apollo 1: accident and 3 deaths on ground• Apollo 8: lunar orbit, pics of earth• Apollo 11: first landing on moon• Apollo 13: accident in transit• Apollo 17: last mission to the moon


We do have the ISS

• http://www.youtube.com/embed/doN4t5NKW-k

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Copyright © 2010 Pearson Education, Inc. Lecture Outline Chapter 5 Earth and Its Moon