1. CH. 29.2 – Solar Activity CH. 29 - MARQUES

2. Terms to know…  Sunspot  Prominence  Granules  solar flare  coronal mass ejection  aurora

3. Solar Activity  Sun rotates on its own axis  once per 27 days  Gases are in constant motion  Granules are just the grainy appearance of the sun and result from small temp/density differences.

4. Sunspots  Sunspots : areas of slower convection (high magnetism)  Vary in size...up to >7x the size of Earth! …showed scientists that the sun does rotate.

5. Sun Spot Cycle 1. Low # of sunspots (groups) begins to increase 2. Appear in groups halfway between equator and poles. 3. Higher latitude sunspots begin to disappear and new ones appear at/near the equator. 4. At approx. 11 years, the number of groups begins to increase again.

6. Solar Eruptions  Prominences: glowing HOT gas from chromosphere form arches with curved magnetic field lines. (lasts weeks or hours)  Solar Flares: sudden/violent/HOT/eruption of ions (e-, p+)  lasts minutes or an hour...  releases E stored in the magnetic fields from sunspots…  can form coronal loops.  Can reach temp of 20 mil o C!

7. Solar Eruptions Cont…  Coronal Mass Ejections: parts of the corona that get thrown off!  particles can strike and disturb Earth’s magnetosphere (geomagnetic storm)  can knock out power grids.

8. Solar Eruptions Cont…  Auroras: interaction of solar wind and the magnetosphere.  Mostly seen @ poles b/c that’s where magnetism is greatest.  Ions strike gas particles in our atmosphere, causing sheets of light.  Peak at the height of sunspot cycle, especially after flares. Why?  Northern lights (aurora borealis)  Southern lights (aurora australis)