Our Star, the Sun

1. Our Star, the Sun

3. The Sun is the Largest Object in the Solar System • The Sun contains more than 99.85% of the total mass of the solar system • If you put all the planets in the solar system, they would not fill up the volume of the Sun • 110 Earths or 10 Jupiters fit across the diameter of the Sun How big is the Sun?

4. An X-ray look at the Sun.http://bcs.whfreeman.com/universe6e/pages/bcs-main.asp?v=category&s=00110&n=01000&i=18110.07&o=|18000|01000|&ns=0

5. The Sun goes through periods of relative activity and inactivity

6. The Sun’s interior has three layers:(1) core(2) radiative zone (3) convective zone Energy generated in the core of the Sun propagates outward through these different layers, and finally, through the atmosphere of the Sun. This process takes tens of thousands of years or more.

7. The Sun’s atmosphere also has three layers… • Photosphere - the layer we see, 5800 K • Chromosphere - the red layer observed using a hydrogen filter, 10,000 K • Corona - the incredibly thin outer atmosphere, 1,000,000 K

8. The photosphere is the visible layer of the Sun Granulation caused by convection http://www.whfreeman.com/universe6e - Seething Granules around a Sun Spot

9. Sunspots are the most well known feature in the photosphere. Monitoring sunspots reveals the Sun’s rotation. http://www.whfreeman.com/universe6e - the motion of a small sun spot

10. The movement of sunspots reveals that the Sun’s rotation takes about … 4 weeks

11. The annual change in numbers of sunspots reveals that the Sun experiences an 11-year Sun Spot cycle Maximum number Minimum number

12. Magnetic field lines connect sunspots on the Sun’s photosphere

13. Above the photosphere, the chromosphere is characterized by its red color – from Ha emission.

14. Solar magnetic fields also create other atmospheric phenomena • prominences

15. Solar magnetic fields also create other atmospheric phenomena • prominences • solar flares

16. The corona, the outermost part of the Sun’s atmosphere, is characterized by its high temperature and low density The Sun also ejects a stream of charged particles into space known as the solar wind

17. Solar magnetic fields also create other atmospheric phenomena • coronal mass ejections (CMEs) • prominences • solar flares

18. http://www.spaceweather.com/http://www.spaceweather.com/images2002/18mar02/cme_c3_big.gifhttp://www.spaceweather.com/http://www.spaceweather.com/images2002/18mar02/cme_c3_big.gif

19. The most powerful solar flare in 14 years, .. erupted from sunspot 486 in late October of 2003. The explosion hurled a coronal mass ejection almost directly toward Earth, which triggered bright auroras when it arrived on Earth.

20. The Earth’s magnetic field is caused by movement of material in Earth’s interior

21. The Earth’s magnetic field produces a magnetosphere that deflects and traps particles from the solar wind protecting Earth

22. Relevance of Earth’s protective magnetosphere • Protects against Solar Flares - violent explosions on the Sun releasing large burst of charged particles into the solar system • Protects against Solar Wind - dangerous stream of charged particles constantly coming from the Sun • Northern Lights (Aurora Borealis)

23. Northern Lights (Aurora Borealis) As the charged particles from the Sun interact with the magnetic field around Earth, the particles collide with the nitrogen and oxygen atoms in the atmosphere and excite those atoms to emit light See Mastering Astro animation

26. Aurora as seen from space