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SUN COURSE - SLIDE SHOW 3. Show 1 -- photosphere & sunspots. Today: SOHO. Show 2 -- corona & solar cycle. 1. SOHO (Solar & Heliospheric Observatory). Computer animation of trip to orbit 1% of distance to Sun New collaborative ESA/NASA mission - launched Dec 1995
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SUN COURSE - SLIDE SHOW 3 Show 1 -- photosphere & sunspots Today: SOHO Show 2 -- corona & solar cycle
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
SOHO Orbit Orbiting Sun at L1 point in phase with Earth Observing Sun continuously for first time Results breathtaking MANY NEW SURPRISES --> only three
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
The SUN Last Week The photo sphere (Big Bear)
The SUN TODAY The photo sphere (SOHO-MDI)
2. QNs. (i) -- ? Earth Influenced by S Variability Number of Sunspots Oscillates w. 11-year Cycle
SURPRISE (1976) Realised NO sunspots in most of 17th centy "Maunder Minimum" -- Little Ice Age So B on Sun affects climate of Earth !! How ??
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
SURPRISE (2001) Discovered that Global B of Sun doubled since 1900 ? Effect on Global T of Earth 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
QN. (ii) -- ? Structure of Solar Interior Guitar string can oscillate in different normal modes Sun too Recently discovered several million
SOHO Measures velocity of Sun's surface at million pts/min Deduces frequencies: Deduced T(r) -- agrees with model to < 1%
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
QN(iii)-? How Do Mass Ejections Occur SOHO Coronagraph -- Artificial eclipse Discovered huge ejections of plasma Can reach Earth - communications / satellites
Other Consequences Damage to satellites, astronauts Disruption to radio/phone communications, power grids
Cause of Eruption Magnetic Catastrophe (2D)
3D Model Magnetic Catastrophe