The most accepted model of the Sun is called the Standard Solar Model .

2. The most accepted model of the Sun is called the Standard Solar Model.

3. It was discovered in the 1960’s that the surface of the Sun vibrates complexly.These vibrations are the result of internal pressure waves that reflect off the photosphere and repeatedly cross the solar interior.

4. The study of these waves is as close as we can get to studying the solar interior. The study of these solar surface patterns is called helioseismology.

5. Image to the right in the H-alpha region of the spectrum

6. Sun tsunami

7. Solar Shock Wavevideo playback

9. One of the most recent studies is GONG (global oscillations network group).

10. Studying these “sunquakes” allows scientists to find the density of different layers of the sun.

11. The density variance throughout the Sun is great: • Core 150 g/cm3 (20 x Fe) • Intermediate 1 g/cm3 (H2O) • Photosphere 10-7 g/cm3 (10,000 x less than Earth surface air) • Far Corona 10-26 g/cm3 (as thin as the best vacuum physicists can create)

13. The temperature change is not as rapid:15,000,000 K at core6,000 K at photosphere

14. In and near the core, the high temperature ionizes all gas molecules. Therefore, the solar interior is very transparent to radiation, so nuclear energy travels outward very easily.

15. This region through which radiation travels easily is the radiative zone. At the outer edge of the radiation zone, the numerous electrons orbiting the nuclei make the gases totally opaque to radiation.

17. Therefore, no photons can escape, but what happens to the energy? It must be released or the Sun would explode. Convection is the method that releases the energy.

19. Gases physically move upward from the radiation zone to the surface through this convection zone. (There are actually many stacks of convection cells which become progressively smaller the further they are from the core.)

21. Actually, only the top cell can be seen, those below are inferred.At the area of the photosphere the gas is too thin to be convected. At this point, the energy leaves by radiation.

22. Convection does not occur past the photosphere into the solar atmosphere because the gases are too thin to be convected.

23. Nextsolar convection simulationsolar convection currentsorange sun oozing

27. Let’s trace a “packet” of energy from its formation in the solar core to its arrival at Earth:1. Nuclear fusion produces a gamma-ray photon.

28. 2. This photon is continually scattered by electrons as it moves out through lower and lower temperatures. This scattering causes the photon to lose energy.

29. 3. The photon reaches the base of the convection zone as an x-ray photon (lower in energy than the gamma-ray photon).(steps 1,2, and 3 take 10,000’s of years)

30. 4. The photons are absorbed at the convection zone, and the energy is carried up by convection. It arrives in the photosphere a few 100,000 years later.

31. 5. Above the convection zone, the energy leaves as visible light radiation and reaches Earth in about 8 minutes. The sunlight we see starts at the photosphere.

32. The solar interior takes lethal high-energy radiation and converts it to lower-energy light.