1. The Sun Chapter 28

2. Basic Properties Composition of sun 0.8% 70% 28% 0.3% 0.2%

3. Basic Properties 332,000x mass then earth 695,000 km at equator 6,000°C average temp. Rotates 1 about every 30 days Age= ~5.0 billion years old

4. Structure of the Sun 3 Regions –Core –Inner Zone –Atmosphere

5. The Core ~10% of the sun 15,000,000° C Made up of gas Because of gravity the core is 10x denser than iron

6. The Core Heat in the core causes electrons of the atoms to roam free Exposed nuclei is then changed by nuclear reactions Give a hydrogen fusion reaction

7. Hydrogen Fusion Step 1 –2 hydrogen nuclei collide and fuse Step 2 –One of these protons changes into a neutron Step 3 –Another proton combines with the proton-neutron pair, producing a nucleus of 2 protons and 1 neutron Step 4 –2 of these nuclei collide and fuse Step 5 –Resulting cluster throws off 2 protons, leaving behind a nuclei of 2 protons and 2 neutrons

8. Hydrogen Fusion Energy is given off in every step Changes more then 600,000,000 of H into He every sec.

9. Mass into Energy 1905-Albert Einstein proposes the Theory of Relativity Proposed this before nuclear physics E=mc² E represents energy produced, m represents mass, and c represents the speed of light

10. The Inner Zones 2 regions within this zone –Radiative Zone –Convective Zone

11. Radiative Zone Zone that surrounds core 2,500,000°C Energy moves from atom to atom in the form of electromagnetic waves, or radiation

12. Convective Zone Zone around radiative zone About 1,000,000°C Energy moves by convection Hot gases rise, and cool gases sink

13. Sun’s Atmosphere Uppermost region of solar gases Photosphere Chromosphere Corona

14. Photosphere Innermost layer of atmosphere Surface of the sun-what we see ~6,000°C Grainy appearance-Granulation –Caused by the rising and sinking of gases from the Convective zone

15. Chromosphere Chromosphere = Color sphere Thin layer of gases that glows reddish light Temp. ranges from 4,000- 50,000°C Gases move away and towards the photosphere May form narrow jets of gas that shoot outward

16. Corona Crown of the sun-Outermost layer Huge cloud of gas heated by sun’s magnetic field ~2,000,000°C Prevents most of the atomic particles from sun escaping into space Atomic particles that escape cause solar wind

17. Solar Activity Parts of the sun rotate at different speeds Equator rotates faster than the poles –Equator ~25 days –Poles ~33 days Average rotation is 27 days Gases in sun are in constant motion Energy and gravity are main reason Sun also rotates on its axis

18. Sunspots Magnetic fields slow down activity in convective zone Slower convection means less gas transfers heat This causes cooler areas on the surface called sunspots Sunspots run in a 11 year cycle

19. Prominences As a result of sunspots, prominences may form Huge arches that reach above the surface Each one follows a magnetic field path

20. Solar Flares One of the most violent solar disturbances Sudden outward eruption of electrically charged atomic particles Cause magnetic storms on earth Solar Flare Movie

21. Auroras As a result of these magnetic storms, the Aurora Borealis occurs Solar particles are attracted to the poles by the magnetosphere These particles come in contact with gas molecules in the upper atmosphere and produce the northern lights

26. Formation of the Solar System Each solar system that forms has four basic properties –Patterns of motion among large bodies –Two major types of planets –Asteroids and Comets –Exceptions to the Rules

28. Formation of the Solar System Solar Nebular Theory –Theory that describes the formation of the solar system –Accretion of particles began ≈5 bya

29. Formation of the Planets As the sun was spinning, small bodies of matter called planetismals began clumping together Planetsimals smash together and form protoplanets

30. Formation of the Planets These protoplanets gain mass through accretion Different materials in the gas cloud will condense at different temperatures Rock planets versus gas planets

31. Formation of the Planets Frost Line –Determines what type of planets will form –Planets beyond frost line will be gas planets –Inside of frost line will be rock planets

32. Formation of the Earth 3 sources of heat –Collision of planetismals –Increasing weight of the outer layers –Radioactive materials within the earth

33. The Solid Earth Density Stratification –The young earth was a giant ball of molten lava –Heavier elements sink to the middle of planet Caused the earth to separate into about 3 layers –Core –Mantle –Crust

34. The Atmosphere Earth managed to capture some H and He that was in the solar nebula This first atmosphere was lost to space as a result of some cosmic force

35. Formation of the Atmosphere Our present day atmosphere came mostly from outgassing of materials Outgassing is when gas escapes to the surface from inside –Volcanoes

36. Formation of the Oceans Eventually, enough gases escaped and started to condense Some paleoclimatologists have speculated that the earth rained for ≈25 my Water would evaporate instantly back into the atmosphere Eventually the earth cooled and oceans began to form