1. I.The Solar Spectrum : Sun’s composition and surface temperature II.Sun’s Interior: Energy source, energy transport, structure, helioseismology. III.Sun’s Atmosphere: Photosphere, chromosphere, corona IV.Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares. Outline of The Sun (Ch. 10) (Not exactly like the book)

2. I. Solar Spectrum: Composition and Surface Temperature

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4. I. Solar Spectrum: How do we know the composition of the Sun?

5. What type of Spectrum is this?

6. How do we know this? Surface Temperature: approximately 6,000 K

7. I.The Solar Spectrum : Sun’s composition and surface temperature II.Sun’s Interior: Energy source, energy transport, structure, helioseismology. III.Sun’s Atmosphere: Photosphere, chromosphere, corona IV.Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares. Outline of The Sun (Ch. 10)

8. What is the source of the Sun’s energy? a) Chemical reactions b) Gravitational contraction c) Nuclear fission (like in nuclear power plants) d) Nuclear fusion Question 1

9. Why does the Sun shine?

10. Is it on FIRE? Fuel Rate of burning that fuel

11. Is it on FIRE? Luminosity ~ 10,000 years Chemical Energy Content

12. Is it on FIRE? … NO! Luminosity ~ 10,000 years Chemical Energy Content

13. Is it CONTRACTING?

14. Luminosity Gravitational Potential Energy Is it CONTRACTING? ~ 25 million years

15. Luminosity Gravitational Potential Energy Is it CONTRACTING? … NO! ~ 25 million years

16. E = mc 2 - Einstein, 1905

17. Is it powered by NUCLEAR ENERGY? Luminosity ~ 10 billion years Nuclear Potential Energy (core)

18. Is it powered by NUCLEAR ENERGY? … YES! Luminosity ~ 10 billion years Nuclear Potential Energy (core)

19. What is the source of the Sun’s energy? a) Chemical reactions b) Gravitational contraction c) Nuclear fission (like in nuclear power plants) d) Nuclear fusion Question 1

20. Fission Big nucleus splits into smaller pieces (Nuclear power plants) Fusion Small nuclei stick together to make a bigger one (Sun, stars)

21. 4 protons  one Helium nucleus + Energy Hydrogen Fusion into Helium in the Sun’s Core

22. 4 protons  one helium nucleus + Energy The mass of the four protons is higher than that of the helium nucleus where did the missing mass go? Hydrogen Fusion into Helium in the Sun’s Core

23. 4 protons  one helium nucleus + Energy The mass of the four protons is higher than that of the helium nucleus where did the missing mass go? The mass became energy, and E=mc 2 so a little mass can produce a lot of energy Hydrogen Fusion into Helium in the Sun’s Core

24. Proton-proton chain is how hydrogen fuses into helium in Sun

25. Sun’s interior

26. Core: Energy generated by nuclear fusion

27. Radiation Zone: Energy transported upward by photons

28. Convection Zone: Energy transported upward by rising hot gas

29. In the Sun, gravity is balanced by outward pressure (due to the outflow of energy)

30. Solar Thermostat Temperature Restored Temperature Decreases Fusion Rate Decreases Core compresses

31. Solar Thermostat Temperature Restored Temperature Increases Fusion Rate Increases Core expands

32. Helioseismology By studying the motion of the Sun’s surface we can learn about its interior in a similar way to the study of Earthquakes.

33. What have we learned? How does the solar thermostat work? There is a equilibrium between gravity and energy outflow……. How does the energy from fusion get out of the Sun? Energy is produces in the core by nuclear fusion and it gets radiated outward. The convection zone carries energy the rest of the way to the photosphere, where it is radiated into space as sunlight. How do we know what is happening inside the Sun? Helioseismology and other techniques

34. I.The Solar Spectrum : Sun’s composition and surface temperature II.Sun’s Interior: Energy source, energy transport, structure, helioseismology. III.Sun’s Atmosphere: Photosphere, chromosphere, corona IV.Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares. Outline of The Sun (Ch. 10)

35. Photosphere: Visible surface of Sun T ~ 6,000 K

36. Chromosphere: Middle layer of solar atmosphere

37. Corona: Outermost layer of solar atmosphere

38. Solar Granulation in the Photosphere

39. Convection (rising hot gas) takes energy to surface

40. Cloud tops on Earth produced by convection: warm air rises

41. Sunspots

43. Sunspots and Solar Rotation

44. Why do sunspots look dark? a) They are dark clouds b) They are smoke from the Sun’s interior c) They are cooler than the rest of the Sun’s surface d) None of the above Question

45. Why do sunspots look dark? a) They are dark clouds b) They are smoke from the Sun’s interior c) They are cooler than the rest of the Sun’s surface d) None of the above Question

46. Loops trace magnetic field lines

47. Blackbody radiation: The hotter the brighter The hotter the bluer Why do sunspots look dark? They are cooler than the rest of the Sun’s surface Are they redder? Review from Ch 5

48. Sunspots

49. Visible during a total solar eclipse Solar Chromosphere

51. Visible during a total solar eclipse Solar Corona

52. Coronal mass ejections send bursts of energetic charged particles out through the solar system

53. I.The Solar Spectrum : Sun’s composition and surface temperature II.Sun’s Interior: Energy source, energy transport, structure, helioseismology. III.Sun’s Atmosphere: Photosphere, chromosphere, corona IV.Solar Activity: Sunspots, solar magnetism, solar cycle, prominences and flares. Outline of The Sun (Ch. 10)

54. I.Sunspots: main indicator II.Prominences and flares: also indicators of solar activity III.Solar cycle: 11-year cycle IV. Solar Activity

55. Charged particles streaming from Sun can disrupt electrical power grid and can disable communications satellites

56. Energetic particles high in Earth’s atmosphere cause auroras (aka Northern Lights)

57. How does solar activity affect humans? Bursts of charged particles ejected from the Sun during periods of high solar activity can hamper radio communications,disrupt electrical power generation,and damage orbiting satellites. Solar activity can also have a strong impact on Earth’s weather

58. Sunspot numbers and temperature on Earth: During the mid-to-late 1600s records indicate a very cold period on Earth