1. Structure of the Sun & Solar Activity

4. Parts of the Sun
Core: enormous pressure & high temperatures cause the fusion of hydrogen into helium (15 million ºC)
Corona: very hot, creates solar wind, only visible during a solar eclipse (1 million ºC)
Photosphere: innermost layer of atmosphere – VISIBLE LIGHT (6 thousand ºC)
Radiation Zone: energy from the core moves through the radiative zone in the form of electromagnetic radiation (2-7 million ºC)
Convective Zone: hot gasses move outward, cool, contract, sink, repeat (2 million ºC)
Chromosphere: gives off redish light from Hydrogen (4-50 thousand ºC)

5. Solar Activity (not part of your notes)
The sun is in constant motion.
Parts of the sun rotate faster than others.
The equator moves the fastest, the poles the slowest.
It takes an average of 27 days for the sun to make one rotation.

6. Sunspots
Dark areas of the photosphere of the sun, that are cooler than the surrounding areas, and have a strong magnetic field.
Caused by magnetic fields created through the movement of gasses (rotation and convection).
The sunspot cycle lasts 11 years.

7. Sunspot Cycle Graph
11 years from low to low

8. 2008 also experienced a 50 year low in solar wind pressure.
SUNSPOTS
Sept 27, 2001
Sept 27, (200+ days with no sunspots)
2008 also experienced a 50 year low in solar wind pressure.

9. Solar Activity (Ejections)
Affected by the sunspot cycle
Solar Ejections are when the sun emits atomic particles:
Prominences
Solar Flares
Coronal Mass Ejections (CME’s)

10. Erupting Prominences
Huge arches of glowing gasses that connect areas (in the sun’s atmosphere) that have positive magnetic energy to areas with negative magnetic energy.
Caused by the same magnetic fields that create sunspots.

11. Prominences

12. Coronal Mass Ejection
Particles (or parts of the corona) are thrown off the sun.
Strike Earth’s magnetosphere creating disturbances called geomagnetic storms.
Geomagnetic storms can disturb radio communication, damage satellites and cause auroras.

13. Earth’s Magnetosphere

14. Earth’s Magnetosphere
A magnetic field surrounding the earth – affected by solar wind and the magnetic fields of other space objects.
Protects the majority of the Earth from the solar wind.
Solar wind is a stream of electrically charged particles (protons & electrons) flowing from the sun.

16. Solar Wind

17. Computer Animation of a CME creating Auroras on Earth – notice Earth’s magnetosphere. (Wait for animation to start )

18. Solar Flares Sudden outward eruption of charged particles
The trigger is unknown.
During a peak , 5-10 can occur in one day
Particles that escape will increase the strength of the solar wind

20. Geomagnetic Storm Effects
Radiation Hazards to humans – especially those in space
Migratory animals less able to navigate (esp. homing pigeons)
Communication Disruptions: ground-to -air, ship-to-shore, shortwave broadcast, and amateur radio.

21. Geomagnetic Storm Effects
GPS & Loran navigation disruptions
Satellite hardware damage
Power Grid Outages – 1989 Quebec & NE US was out for 9 hours (affecting 6 million people)

22. Examples for Foldable