1. Goal: To understand how the sun works Objectives: 1)Journey to the center of the sun!

2. Spaceship Sol Scheduled departure time: 5 min. Please fasten seatbelts. What color is The sun? a)Yellow b)Orange c)Blue d)White e)Red

3. Spaceship Sol Scheduled departure time: 4 min. Prepare for departure. Is the sun a “star”? a)Yes b)No

4. Liftoff! Travel distance: 93 million miles

6. Heliosphere: Solar Wind speed: 390.0 km/s density: 7 protons/cm 3 Outside temp: 292K 68 F Density outside: Almost 0.

7. Outside temp: 400K 262 F Density outside: 10 protons/cm 3

8. Outside temp: 450K 352 F Density outside: 28 protons/cm 3

9. Outside temp: 604K 618 F Distance to sun: 20 million miles Density outside: 140 protons/cm 3

10. Outer area of the corona - the start of the solar wind Outside temp: 1208K 1705 F Distance to sun: 5 million miles Density outside: 2200 protons/cm 3

11. Corona: millions of degrees! Outside temp: 2415K 3879 F Distance to sun: 1.25 million miles (0.8 million from the surface) Density outside: 35000 protons/cm 3

12. Corona Outside temp: 1 million K! 100k miles from the surface

13. Chromosphere Outside temp: 10000K 1k miles from the surface CORONAL MASS EJECTION!!!

14. Rotation of the sun. The sun rotates every 26-28 days, depending on where on the sun you are. Why could this be important?

15. Photosphere Outside temp: 5800K Surface! Density: 1% of air. All of the sun’s light that we see comes from here. Question: If we fly in onto that sunspot, will it be dark or light?

16. Photosphere Outside temp 5800K Surface (400 km deep)! Sunspots are light! They are 1-2k cooler, so compared to the rest of the sun, they appear to be darker. Granules: Convection cells. Kind of like in a pot of boiling water.

17. Welcome to the sun! http://www.nasa.gov/mpg/118091main_other_loop_sm.mpg http://www.nasa.gov/mpg/118091main_other_loop_sm.mpg

18. Warning: breathing apparatus will be required as the sun is made of 74% Hydrogen, 25% Helium, and only 1% other stuff. Question: where on or in the sun is there a solid surface to land on?

19. How dense is the sun? A) About the density of air B) About the density of water C) About the density of lead D) more dense than any material on earth

20. How dense is the sun? B) About the density of water The average density of the sun is only 40% more than the density of water. Density of the sun is 1.4 g/cm 3, vs. 1.0 for water.

21. Convective zone: Starts at the bottom of the photosphere and goes down for about 200k km. Temperature: 6k on the top 2 million on the bottom! Density gets up to 1/10 th the density of water. Energy is transported through convective cells.

22. Radiative Zone Average density is water. This is a stable region, kind of like the Stratosphere on the earth. Starts 200k km below the photosphere, and ends 200k km above the center of the sun. That is 50% of the radius of the sun! Energy is transferred by radiation. Temperature ranges from 2 to 7 million degrees Kelvin! How long do you think it takes light to pass through the Radiative Zone?

23. Time for light to pass through the Radiative Zone: Light will be scattered from 1 particle to the next (sort of like light scattered by water, but even worse, and imagine a pool of water about 400k km deep!). Even though light travels at the speed of light, it STILL takes 1 MILLION years for a photon of light to get through this layer!

24. The Core! The core is the engine of the sun and is the bottom 100-200k km of the sun. In the core, the force of gravity is pretty intense. Temperature: up to 15 million degrees Kelvin! Density: up to 150 times the density of water!

25. Hydrostatic Equalibrium Here there is a tug of war. Gravity is pulling down Gas pressure and radiative (light) pressure are pushing up. The sun has to produce lots of energy just to keep itself from collapsing under its own weight! This is called Hydrostatic Equilibrium. Very special and important things happen when this equilibrium are broken, but more on that later in the course

26. Conclusion The sun is a wild, crazy, and often violent place. It has weather that puts any weather the earth has to same. Coronal mass ejections, if pointed right at the earth, can do serious damage to satellites, and possibly even our electric grid!