1. Show 1 -- photosphere & sunspots SUN COURSE - SLIDE SHOW 3 Show 2 -- corona & solar cycle Today: SOHO

2. 1. SOHO (Solar & Heliospheric Observatory) Computer animation of trip to orbit 1% of distance to Sun New collaborative ESA/NASA mission - launched Dec 1995 --> 1st comprehensive view of Sun

3. SOHO Orbit Orbiting Sun at L1 point in phase with Earth Observing Sun continuously for first time Results breathtaking MANY NEW SURPRISES --> only three

4. Suite 11 Instrument Packages Solar wind - SWAN, CELIAS, CEPAC Atmosphere: * LASCO - Visible Light Coronagraph - UVCS - Ultraviolet Coronagraph - * EIT - Extreme UV telescope - global images- CDS - Spectrum EUV -> n, T, v + raster SUMER - Spectrum EUV -> n, T, v + raster Interior * MDI - Oscillations Imager + B GOLF - Global Velocity Oscillations * VIRGO - Irradiance Variations

5. E.G. from CDS

6. The SUN Last Week The photo sphere (Big Bear)

7. The SUN TODAY The photo sphere (SOHO- MDI)

8. Magnetic field (SOHO- MDI)

9. Chromo sphere (Ha - Big Bear)

10. Chromo sphere (CaK - Big Bear)

11. Chromo sphere (SOHO- EIT)

12. Corona at 1.3 MK (EIT)

13. Corona at 1.6 MK (EIT)

14. Corona at 2.3 MK (EIT)

15. 2. QNs. (i) -- ? Earth Influenced by S Variability Number of Sunspots Oscillates w. 11-year Cycle

16. SURPRISE (1976) "Maunder Minimum" -- Little Ice Age So B on Sun affects climate of Earth !! How ?? Realised NO sunspots in most of 17th cent y

17. SOHO --> Total Emission (t) 1996-2000 Emission varies by 0.2% -- passage sunspots Increase by 0.1% from sunspot min to max ? Contribution to global warming

18. SURPRISE (2001) Discovered that Global B of Sun doubled since 1900 Observed increase in T (blue) Best estimate of increase caused by Sun (yellow) Only 1/3 global warming (1970 to 2000) caused by Sun ? Mechanism couple Sun/climate ? Effect on Global T of Earth

19. QN. (ii) -- ? Structure of Solar Interior Guitar string can oscillate in different normal modes Sun too Recently discovered several million

20. SOHO Measures velocity of Sun's surface at million pts/min Deduces frequencies: Deduced T(r) -- agrees with model to < 1%

21. Deduce Internal Rotation Observe: * Faster at equator -- Expect: * const. on cylinders * B generated throughout conv. zone Surprise: -- const on radial lines -- intense shear layer ? site dynamo

22. QN(iii)-? How Do Mass Ejections Occur SOHO Coronagraph -- Artificial eclipse Can reach Earth - communications / satellites Discovered huge ejections of plasma

23. Comet + Comet

24. Next

25. TODAY - SOHO LASCO Corona- graph

26. Further Out (LASCO C3)

27. ? Effect on the Earth -- Space Weather

28. Other Consequences Damage to satellites, astronauts Disruption to radio/phone communications, power grids

29. Cause of Eruption Magnetic Catastrophe (2D)

30. 3D Model Magnetic Catastro phe