1. Chapter 29-2 Solar Activity

2. Solar Activity • Gases in constant motion (rising and sinking) • Sun rotates on axis

3. Not a solid • Ball of hot gases • Close to equator – 25.3 Earth days to rotate once • Poles – 33 days • Average – 27 days

4. Sunspots • Gases in convection zone + Sun’s rotation = Magnetic Field • Cause convection currents to slow in areas • Cooler areas

5. Sunspots • Shine bright but less than surrounding areas • Appear darker • Located in Photosphere

6. Granulation – grainy appearance of Photosphere

7. Sunspot Cycle • Observation of sunspots show Sun’s rotation • 11 year cycle • Start with few • Increases to 100 • Then start to diminish

9. Solar Ejections • Caused by change in magnetic field • Sun atomic particles • Prominences • Solar flares • Coronal mass ejections

10. Prominences • Clouds of glowing gases • Arch above surface • Follow curve of magnetic forces • Lasts hours to weeks

11. Solar Flares • Most violent • Outward eruption of charged particles • Release of energy from sunspots • Thousands of meters

12. Coronal Mass Ejection • Parts of the corona that are thrown off the sun • Particles can strike Earth’s magnetosphere • Cause geomagnetic storms

14. Interfere with radio communication • Damage satellites • Blackouts

15. Auroras • Interaction between solar winds and Earth’s magnetic field • Bands of light

16. Charged particles from sun hit atoms of gas in upper atmosphere • Produce sheets of light

17. Northern Lights – Aurora Borealis

18. Southern Lights – Aurora Australis

19. 100 – 1,000 km above surface • Visible in US – 4 to 5 times a year • Alaska – much more frequent • Seen from space • Jupiter and Saturn