Post on 12-Jan-2016
The solar system and a lot of science-y words
Astronomy 115, Spring 2013
Comparing the Sun and Earth
Comparing the Sun and Earth
size:
1) The radius of the Earth is r = 6371 km
2) The radius of the Sun is R = 7x105 km
R
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 to Earth masses = 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….
What is the densest round object in the solar system?
1. Jupiter2. Earth3. Sun4. Venus
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 paper clip 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 lead is 10.8 g cm-3
Comparing the Sun and EarthComposition:
Earth (rocks)
34.6% iron
29.5% oxygen
15.2% silicon
12.7% magnesium
2.4% nickel
1.9% sulfur
Earth (air)
78% nitrogen
21% oxygen
0-4% water
1% argon
0.035% carbon dioxide
0.0017% methaneSun
92.1% hydrogen
7.8% helium
0.1% carbon or oxygen
0.001% iron
Comparing the Composition of the Earth and Planets:
Earth
34.6% iron
29.5% oxygen
15.2% silicon
12.7% magnesium
2.4% nickel
1.9% sulfur
Jupiter
92.1% hydrogen
7.8% helium
0.1% carbon &
oxygen
0.001% iron
Neptune
(Atmosphere)
83% hydrogen
15% helium
2% methane
(Interior)
?? water ice
?? silicon
?? iron
?? oxygen
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 s lightning, storms
104 -105 s tides, diurnal cycle
107 s seasons
1011 - 1012 s ice ages, climate changes
1015 - 1016 s plate tectonics, magnetic polarity reversals, evolution
1017 s age of Earth (4.5 billion years)
The most significant changes to surface conditions on the Earth were brought about by loss of some atmospheric gases and the
emergence of life.
Changes in the Earth’s atmosphere
Time and Evolution:The Early Earth
atmosphere similar to solar composition
100x thicker than today
hydrogen-helium
4.5-3.5 billion years (by) ago
The Young Earth
hydrogen/helium lost
oceans form/ CO2 from volcanic activity
CO2 dissolved in oceans
3.5 – 0.5 by
The Living Earth (0.5 by to Present)
nitrogen dominates as CO2 is lost/modern atmospheric density
plants evolve (photosynthesis begins) - oxygen concentration increases - feedback with sun’s evolution.
animals adapt to O2 metabolism - move to land
O2 in atmosphere: life’s smoking gun/impossible without
Comparing the Sun and Earth
Time and Evolution:
The Sun
104 s Convection at visible surface
105 - 106 s Flares – solar events – Oscillations
2x106 s Solar rotation
107 - 108 s Magnetic cycle
1015 - 1016 s Energy transport – Changes in core
1017 s Age of Sun (4.5 billion years)
2x1017 s Sun becomes a red giant/stellar death
Temperature Scales
K = 273 + (°F - 32)/1.8
Comparing the Sun and Earth
Temperature:
SunSurface 5000 – 10000 K (visible)
Atmosphere 2 million K (Corona)
Core 15 million K
EarthSurface 300 K (average ground)
Atmosphere 300 – 1000 K (ground to top)
Interior 3000 – 7700 K
K = 273 + (°F - 32)/1.8
273 K = 32°F, 373 K=212° F, and 273 K = 0°C
Put the following regions of the Sun in order from hottest to coldest
1. Core, atmosphere, surface2. Core, surface, atmosphere3. Surface, atmosphere, core4. Surface, core, atmosphere5. Atmosphere, core, surface6. Atmosphere, surface, core
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
– Kinetic energy (energy of motion)– Thermal energy (energy of heat)– Electromagnetic energy– Gravitational 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 time, orwatt (W) = joules (J) /seconds (s)
• Power Companies use kilowatt-hours as unit of energy or 1000 x (J/s) x hr
1 kWh = 3.6 x 106 J
How much energy do we use?
A typical power bill in the Seattle area will be for about 1200 kilowatt hours (kWh) in one month, or about 400 kWH per person.
The USA as a whole uses
400 kWh x 12 month x 3.0 x 108 people = 1.44 x 1012 kW h
How does that compare with the Sun?