Chapter 8: Planet Earth Outline

1
Chapter 8 Planet Earth Outline

• Basic Properties (mass, radius, density, age,
  albedo, vis-a-vis other planets)
• Simple lab verification for Earths motions
• Orbital speed aberration of starlight
• Rotation on axis Foucault pendulum
• Atmosphere
• Composition
• Wind patterns convection, Coriolis force
• Greenhouse effect Global warming (CO2)
• Ozone depletion
• Earths Interior
• Crust, mantle, outer/inner core increasing
  density a result of differentiation
• Magnetic field dynamo, field reversal on
  geological timescale
• Drift of magnetic pole
• Aurora
• Surface features Continental drift
• Seismic events P and S waves
• Tectonic plates, rifts and spreading of ocean
  floor
• History of Earths surface
• Evidence of Glaciation, volcanism

2
Course AnnouncementsMonday September 27

• Observing test
• Excellent weather continues dont wait until
  its cold and cloudy!
• Observing sheets available from graduate TA on
  roof
• Observing 8pm -10 pm roof of Van Allen Hall
• Study star chart e.g. skyandtelescope.com, pick
  out 5-10 objects before being tested

3
Observing Focus of the WeekThe Harvest Full Moon

• Next Full Moon is tomorrow (Tuesday Sep 28)
• Called Harvest Moon always the full moon closest
  to the fall equinox
• Two principal types of features
• Craters
• Maria (seas)
• Use binoculars for best views
• In S-SE Sky all week
• Rising times
• Monday 650 pm
• Wed. 732 pm
• Friday 850 pm

4
Moon Map (S up,
Moon Map (N is up) with a few prominent features
Plato
Sea of serenity
Apollo 11 landing site in Sea of Tranquility
Copernicus
Sea of tranqullity
Ocean of Storms
Tycho
5
Energy sources Balloon demonstration

• Fission, fusion, vs. chemical energy
• Chemical All familiar energy sources on Earth
  use chemical reactions (e.g. fossil fuels,
  explosives)
• Fusion Solar energy is (ultimately) derived from
  fusion at center of the Sun
• Fission used in nuclear power plants to make
  heat -gt steam turbine -gt electricity (Palo, IA)
• A gram of fuel produces 107 times as much energy
  in fusion compared with any chemical reaction
• Example of chemical reactions Iginition of
  Helium, Oxygen, Hydrogen, Oxygen/Hydrogen mixture
  balloons

6
(No Transcript)
7
The Earths atmosphere, oceans, and surface are
extraordinarily active

• A Blue Planet
• 70 of Earths surface is covered with water.
• Most of the oceans motions are ultimately
  powered by the Moons gravitational attraction
  and the Earths rotation.

8
The Earths atmosphere, oceans and surface are
extraordinarily active.

• Earths surface is shaped by
• Plate Tectonics
• Volcanism
• Erosion
• Impacts (asteroids)
• Although Earth is 4.6 billion years old, much of
  the surface is less than 100 million years old.

9
Observational verifications of Earths rotation
and orbital motion

• 1 Orbital motion
• Stellar Aberration
• 2. Rotation on axis
• Foucault pendulum
• Coriolis force

Galileo (c.1635) Eppur si muove still it moves
supposedly muttered quietly after conviction in
inquisition
10
Measuring Earths Rotation about the Sun
Aberration of Starlight
Moving observer sees raindrops move downward at a
small angle to vertical

• Starlight arrives at moving Earth (like rain
  above)
• Since Earth is moving in its orbit , apparent
  direction of starlight is shifted
• Angle shift is /-20 arc.
• Shift is annual (/- 20 over 12 months)
• Discovered by Bradley (1720)

11
Stellar Aberration

• Position of all star shift annually as Earth
  rotates in its orbit
• Maximum magnitude of shift is

12
Measuring the Rotation of the Earth on its
axis Foucault Pendulum (1851)
Pantheon (Paris) Tombs of Rousseau, Victor Hugo
in basement
13
Pendulum motion

• Pendulum oscillates in a plane fixed w.r.t stars
• Rotation period P 24 hours/sin(latitude)
• Period is infinite (no effect) at equator
• At Iowa City, period would be 36.6 hr

14
Another effect of Earths rotation The Oblate
Earth
Equatorial diameter is 40 km larger than polar
diameter
A person weighs 150 lb at the North pole. How
much would he weigh at the equator?
Answer 148lb (2 lb lighter)
15
AtmosphereWind Patterns, Coriolis Force
16
The Earths atmosphere, oceans and surface are
extraordinarily active.

• Atmosphere is 80 nitrogen and 20 oxygen.
• Atmospheric motions are ultimately powered by the
  Suns energy.
• Earths reflects about 39 of Suns energy back
  into space (albedo).

17
Major Atmospheric Flows 3 in each
hemisphere Consequence of solar heating and
Coriolis force
18
Earths atmospheric layers are defined by
temperature ranges.
70?F
-65?F
Height of jets
19
(No Transcript)
20
(No Transcript)