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. Ch. 10 HW has been assigned and is due next Monday March 28

3. I. Solar Spectrum: Composition and Surface Temperature

4. 76 22

5. I. Solar Spectrum: How do we know the composition of the Sun? How do we measure the composition of stars?

6. I. Solar Spectrum: How do we know the composition of the Sun? What type of Spectrum is this?

7. How do we know this? Name two methods to determine the temperature of stars? Surface Temperature: approximately 5,800 K

8. Solar Spectrum: Composition and Surface Temperature

9. 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)

10. 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

11. Is it on FIRE?

12. Luminosity ~ 10,000 years Chemical Energy Content

13. How old is the Sun?

14. How old is the Sun? about 4.6x10 9 years

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

16. Is it CONTRACTING?

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

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

19. E = mc 2 - Einstein, 1905

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

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

22. How old is the Sun? about 4.6 billion years About how many more years of fuel does the Sun have?

23. 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

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

25. 4 protons  one Helium nucleus + Energy Hydrogen Fusion into Helium in the Sun’s Core

26. 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

27. 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

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

29. Sun’s interior

30. Core: Energy generated by nuclear fusion

31. Radiation Zone: Energy transported upward by photons

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

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

34. What if Lucius Malfoy wanted to freeze the Earth by decreasing the energy from the Sun?

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

36. What if Lucius Malfoy wanted to burn the Earth by increasing the energy from the Sun?

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

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

39. 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.

40. 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

41. 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)

42. Photosphere: Visible surface of Sun T ~ 5,800 K

43. Chromosphere: Middle layer of solar atmosphere

44. Corona: Outermost layer of solar atmosphere

45. Solar Granulation in the Photosphere

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

47. Cloud tops on Earth

48. Sunspots

50. Sunspots and Solar Rotation

51. 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

52. 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

53. Loops trace magnetic field lines

54. 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

55. Sunspots

56. Visible during a total solar eclipse Solar Chromosphere

58. Visible during a total solar eclipse Solar Corona

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

60. 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)

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

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

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

64. 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

65. Sunspot numbers and temperature on Earth: During the mid-to-late 1600s records indicate a very cold period on Earth This corresponded to a period with very few or no sunspots on the Sun