1. The solar system and a lot of science-y words Astronomy 115, Spring 2013

2. Comparing the Sun and Earth

3. size: 1)The radius of the Earth is r = 6371 km 2)The radius of the Sun is R = 7x10 5 km R

4. Comparing the Sun and Earth mass: 1)The mass of the Sun is m = 2 x 10 30 kg 2)The mass of the Earth is m = 6 x 10 24 kg 3)The ratio of Sun to Earth masses = 3.3 x 10 5 If the Sun weighed as much as the aircraft carrier Independence……… The Earth would only weigh as much as two members of its crew….

5. What is the densest round object in the solar system? 1.Jupiter 2.Earth 3.Sun 4.Venus

6. 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

7. Comparing the Sun and Earth Composition: 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%methane Sun 92.1%hydrogen 7.8%helium 0.1%carbon or oxygen 0.001%iron

8. 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.

9. Comparing the Sun and Earth Time and Evolution: The Earth 10 2 -10 4 slightning, storms 10 4 -10 5 stides, diurnal cycle 10 7 sseasons 10 11 - 10 12 sice ages, climate changes 10 15 - 10 16 splate tectonics, magnetic polarity reversals, evolution 10 17 sage 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.

10. 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/ CO 2 from volcanic activity  CO 2 dissolved in oceans  3.5 – 0.5 by The Living Earth (0.5 by to Present)  nitrogen dominates as CO 2 is lost/modern atmospheric density  plants evolve (photosynthesis begins) - oxygen concentration increases - feedback with sun’s evolution.  animals adapt to O 2 metabolism - move to land  O 2 in atmosphere: life’s smoking gun/impossible without

11. Comparing the Sun and Earth Time and Evolution: The Sun 10 4 sConvection at visible surface 10 5 - 10 6 sFlares – solar events – Oscillations 2x10 6 sSolar rotation 10 7 - 10 8 sMagnetic cycle 10 15 - 10 16 s Energy transport – Changes in core 10 17 sAge of Sun (4.5 billion years) 2x10 17 sSun becomes a red giant/stellar death

12. Temperature Scales K = 273 + (°F - 32)/1.8

13. Comparing the Sun and Earth Temperature: Sun Surface5000 – 10000 K (visible) Atmosphere2 million K (Corona) Core15 million K Earth Surface 300 K (average ground) Atmosphere300 – 1000 K (ground to top) Interior3000 – 7700 K K = 273 + (°F - 32)/1.8 273 K = 32°F, 373 K=212 ° F, and 273 K = 0°C

14. Put the following regions of the Sun in order from hottest to coldest 1.Core, atmosphere, surface 2.Core, surface, atmosphere 3.Surface, atmosphere, core 4.Surface, core, atmosphere 5.Atmosphere, core, surface 6.Atmosphere, surface, core

15. 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?

16. 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]

17. Energy and Power Power is energy per time, or watt (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 10 6 J

18. 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 10 8 people = 1.44 x 10 12 kW h How does that compare with the Sun?