Solar System Characteris0cs and Light Waves Homework on Moodle •  Quiz Zero Due Tuesday (10/2/12) •  Wri;en Assignment (EVERYONE – due Tues 10/9/12) •  Moodle Assignments (Due 5 AM Tues 10/9/12) –  Wri0ng Assignment –  Lecture Assignment 1 –  Demo Lab Assignment 1 •  Look at it before demo lab •  Answer it a.er demo lab •  Reading More on Moodle You MUST click this to receive credit. You CANNOT make changes aTer you click this bu;on. Sun-Earth Comparison
Comparing the Sun and Earth
Size:
1)  The radius of the Earth is R = 6.371x103 km.
R
2) The radius of the Sun is R = 7x105 km.
Comparing the Sun and Earth
Mass:
1)  The mass of the Sun is M = 2 x 1030 kg
2) The mass of the Earth is M = 6 x 1024 kg
3) The ratio of Sun’s mass to Earth’s mass = 3.3 x 105
If the Sun weighed as much as the
aircraft carrier Independence………
The Earth would only
weigh as much as two
members of its crew….
Comparing the Sun and Earth
Density:
1)  The density of the Sun is d = 1.4 g cm-3
2) The density of the Earth is d = 5.5 g cm-3
1 paperclip weighs about 1 gram (g)
1 cubic centimeter (cm-3) is about the size of a sugar cube
Water has a density of 1 g cm-3
while iron is 7.874 g cm-3
Comparing the Sun and Earth
Composition by Mass:
Earth (Full)
Earth (Air)
34.6%
Iron
78%
Nitrogen
29.5%
Oxygen
21%
Oxygen
15.2%
Silicon
0-4%
Water
12.7%
Magnesium
1%
2.4%
Nickel
0.035%
CO2
1.9%
Sulfur
0.0017%
Methane
Sun
92.1%
Hydrogen
7.8%
Helium
0.1%
Carbon/oxygen
0.001% Iron
Argon
Comparing the Composition of the
Earth and Planets:
Earth
Jupiter
Neptune
34.6%
Iron
92.1%
Hydrogen
83%
Hydrogen
29.5%
Oxygen
7.8%
Helium
15%
Helium
15.2%
Silicon
0.1%
Carbon &
2%
Methane
12.7%
Magnesium
Oxygen
(Atmosphere)
2.4%
Nickel
1.9%
Sulfur
0.001% Iron
??
Water Ice
??
Silicon
??
Iron
??
Oxygen
(Interior)
Jupiter is almost exactly like the Sun, while the Earth, and to a lesser
degree, Neptune are different.
Comparing the Sun and Earth
Time and Evolution:
The Earth
102 -104 sec.
Electrical Disturbances/Storms
104 -105 sec.
Day-Night cycle - Tides
107 sec.
Seasons
1011 - 1012 sec. Ice Ages/Climate Shifts
1015 - 1016 sec. Continent Drift/Magnetic Field/Life
1017 sec.
Age of Earth (4.5 billion years)
The most significant changes to surface conditions on the Earth were
brought about by loss of atmospheric constituents and the emergence of
life.
Changes in the Earth’s Atmosphere
Time and Evolution:
The Early Earth
Ø  Atmosphere similar to Solar
Composition
The Young Earth
Ø  Hydrogen/Helium Lost
Ø  100x thicker than today
Ø  Oceans form/ CO2 from Volcanic
Activity
Ø  Hydrogen-Helium
Ø  CO2 dissolved in Oceans
Ø  4.5-3.5 billion years
Ø  3.5-0.5 billion years ago
The Living Earth (0.5 byr-Present)
Ø  Nitrogen Dominates as CO2 is lost/Modern density
Ø  Plants evolve photosynthesis-Oxygen Balloons-Feedback with
Sun’s evolution.
Ø  Animals adapt to O2 metabolism-move to land
Ø  O2 in atmosphere: life’s smoking gun/Impossible without
Comparing the Sun and Earth
Time and Evolution:
The Sun
104 sec.
105 - 106 sec.
2x106 sec.
Convection at visible surface
storms Flares-Solar Events-Oscillations
*des Solar Rotation
seasons 107 - 108 sec.
Magnetic Cycle
1015 - 1016 sec.
Energy Transport- Changes in Core
1017 sec.
Age of Sun (4.5 billion years)
2x1017 sec.
Sun a Red Giant/Stellar Death
Temperature Scales °C = (°F -­‐ 32)/1.8
K = °C + 273
Temperature Scales
K = 273 + (°F - 32)/1.8
Comparing the Sun and Earth
Temperature:
Surface
(visible)
Sun
5000-6000 K
Atmosphere 2 million K
Core
15 million K
(Corona)
Earth
Surface
300K
(average ground)
Atmosphere 300-1000K (ground
to top)
Interior
3000-5000K
Energy Production from the Sun:
The Sun dominates the energy ‘budget’ of the
solar system
•  How much energy does the Sun produce?
•  How does the energy reach us?
•  How does it produce that energy?
Energy •  Types of energy – 
– 
– 
– 
– 
– 
Kine0c energy (energy of mo0on) Thermal energy (energy of heat) Electromagne0c energy Gravita0onal energy Chemical energy Nuclear energy •  For big energies: joule (J) •  For small energies: electron-­‐volt (eV) [Note: 1 eV = 1.6x10-­‐19 J] Energy and Power •  Power is energy per 0me, or wa# = joules/seconds •  Power Companies use kilowa;-­‐hours as unit of energy or 1 kWh = 1000 Watt-hours 1000 x (joules/sec) x hours 1 kWh = 3.6 x 106 joules How much energy do we use?
A typical electric bill in the
Seattle area will be for about
1200 kilowatt hours (kWh) in
one month (Mn), or about 400
kWH per person.
In one year, the
USA as a whole uses
400 kWh x 12 Mn x 3.0 x 108 people = 1.44 x 1012 kW h
How does that compare with the Sun?
The Sun’s Energy Output
The Sun outputs 4 x 1026 Watts !!!
or 3 x 1026 kW h/month
or 5 x 1016 kWh/person/month on Earth
versus 400 kWh/person/month for household usage
Power Yard stick: Typical Power Plant – 109 W ( or 1 GW)
Solu0on How many gigawa; power sta0ons would it take to equal the sun’s total power of 4 x 1026 wa;s? gigawa; = 109 wa;s s Power = (Power from one plant)× (number of plants)
Sun'
Sun' s Power
number of plants =
Power from one plant
26
4 ×10 W
26 −9
17
= 4 ×10
= 4 ×10
9
10 W
Intensity Intensity is power density. Units: W/m2 = W m-­‐2 Power
Intensity =
Area
A Solar Intensity
The solar power output is 4 x 1026 Watts.
How much of that hits us?
When the Sun is directly over head, it delivers the equivalent of
22 × 60 Watt light bulbs over each square meter (m2) of
ground!!!
This amount, 1340 W m-2, is known as the Solar Constant
How is solar energy delivered from the Sun to
the Earth?
As Light!!!!