Total Eclipse of the Sun Dr Steve Barrett 1 15 May 2008 Total Eclipse of the Sun 1 Dr Steve Barrett 15 May 2008 Total Eclipse of the Sun Total Eclipse of the Sun 2 Dr Steve Barrett 15 May 2008 Total Eclipse of the Sun Total Eclipse of the Sun 3 Introduction The Sun Core Surface Atmosphere Eclipses Total Eclipse of 29 Mar 2006 Why? When? Total Eclipse of the Sun 4 000,000,000,000 watts Power ~ 400,000,000,000,000 Solar Vital Statistics Size ~ 100 x Earth ~ 400 x Moon Mass ~ 1,000,000 x Earth Composition ~ 75% hydrogen 25% helium 0.1% other stuff Distance ~ 370 – 410 x Moon Total Eclipse of the Sun 5 Power Source 1871 Hermann von Helmholtz Burning coal, one ton per hour per square foot of the Sun’s surface, would exhaust the fuel in a few million years 1919 Sir Arthur Eddington Conversion of hydrogen to helium could provide enough energy to power the Sun for billions of years Total Eclipse of the Sun 6 Fusion hydrogen → helium + energy
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Total Eclipse of the Sun
Dr Steve Barrett 1 15 May 2008
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Dr Steve Barrett 15 May 2008
TotalEclipse ofthe Sun
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Dr Steve Barrett 15 May 2008
Total Eclipseof the Sun
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3 Introduction
The Sun CoreSurfaceAtmosphere
Eclipses
Total Eclipse of 29 Mar 2006
Why?When?
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4
000,000,000,000 wattsPower ~ 400,000,000,000,000
Solar Vital Statistics
Size ~ 100 x Earth ~ 400 x Moon
Mass ~ 1,000,000 x EarthComposition ~ 75% hydrogen
25% helium0.1% other stuff
Distance ~ 370 – 410 x Moon
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5 Power Source
1871 Hermann von HelmholtzBurning coal, one ton per hour persquare foot of the Sun’s surface, wouldexhaust the fuel in a few million years
1919 Sir Arthur EddingtonConversion of hydrogen to helium couldprovide enough energy to power the Sunfor billions of years
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6 Fusion
hydrogen → helium + energy
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7 Fusion
Mass loss → energy thanks to E = mc 2
600 Mt of H → 596 Mt of He
Sun loses 4 million tons every second
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8 Internal Structure
core
radiationzone
convectionzone
photosphere
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9 Helioseismology (or “Star Quakes” )
Convection zone turbulence can be detected throughthe Doppler shift of the photosphere’s emission lines To
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10 Solar Spectrum
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11 Sunspots
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12 Sunspots
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13 Sunspots
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14 Sunspot Cycle
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15 Sunspot Cycle
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16 Sunspot Cycle
50 years of very low sunspot activity coincidedwith the ‘Little Ice Age’ period of very cold winters
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17 Magnetic Loops
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18 Magnetic Loops
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19 Magnetic Polarity
SN
34 d
30 d
25 d
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20 Flares and Prominences
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21 Corona
Temperature of surface ~ 6,000 K
Temperature of corona ~ 2,000,000 K
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22 Corona
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23 Solar Wind
400 km/s Tota
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24 Aurora Borealis
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25 Aurora Borealis
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26 Eclipses
EclipseThe passage of one object into theshadow cast by another.Thus an Eclipse of the Sun should becalled an Eclipse of the Earth.
OccultationThe passage of one object in front ofanother, hiding the latter from view.
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27 Moon
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28 Eclipses
Total Eclipse ( long )
Total Eclipse ( short )
Annular Eclipse
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29 Transit of Venus 2004
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30 Eclipse Geometry
An eclipse cannot occur at every New Moonbecause the Moon’s orbit is tilted by ~ 5°.
Total Eclipse of the Sun
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31 Eclipse Geometry
The Moon crosses the plane of the Earth’sorbit (the Ecliptic) at a node.
Ecliptic
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32 Eclipse Timing
Synodic MonthNew Moon to New Moon
Draconic MonthNode to Node
Anomalistic MonthPerigee to Perigee
29.53 days
27.21 days
27.55 days
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33 The Saros Cycle
223 Synodic months =
242 Draconic months =
239 Anomalistic months =
6585.32 days
6585.36 days
6585.54 days
Over this time, the saros cycle, the Moon’sorbital periods are back in ‘synch’.
Two eclipses separated by one saros cyclehave similar geometries. To
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34 Saros 139
Date ØM/ØS Length Seen from
1988 Mar 18 1.046 3m 46s Asia
2006 Mar 29 1.052 4m 07s Africa
2024 Apr 08 1.057 4m 28s Americas
2042 Apr 20 1.061 4m 51s Asia
2060 Apr 30 1.066 5m 15s Africa
2078 May 11 1.070 5m 40s Americas
2096 May 22 1.074 6m 06s Asia
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35 Eclipses Coming Soon
Date Saros Length Seen from
2006 Mar 29 139 4m 07s Africa, Turkey
2008 Aug 01 126 2m 27s Greenland, Siberia
2009 Jul 22 136 6m 39s India, China
2010 Jul 11 146 5m 20s S Pacific, S America
2012 Nov 13 133 4m 02s Australia, S Pacific
2013 Nov 03 143 1m 40s Africa
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36 Eclipses
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37 Eclipses
1715
1724
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38 Total Eclipse of 29 Mar 2006
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39 Total Eclipse of 29 Mar 2006
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40 Total Eclipse of 29 Mar 2006
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41 Total Eclipse of 29 Mar 2006
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42 Eclipse Cruise
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Dr Steve Barrett 8 15 May 2008
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43 Libya
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44 Libya
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45 Eclipse Track
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46 Eclipse Site
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47 Eclipse Track
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48 Setting Up in the Desert
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Dr Steve Barrett 9 15 May 2008
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49 The Eclipse Starts…
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50 Totality!
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51 Catching the Corona
1/4000 s
1/1000 s
1/250 s
1/60 s
1/15 s
1/4 s
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52 Total Eclipse of the Sun 2006
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53 Total Eclipse of the Sun 2006
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54 Total Eclipse of the Sun 2006
Total Eclipse of the Sun
Dr Steve Barrett 10 15 May 2008
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55 Viewing Totality
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56 Viewing Totality
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57 Shadow Bands
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58 Green Flash
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59 An African Experience
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60 http://www.liv.ac.uk/~sdb/ Talks
Dr Steve Barrett 15 May 2008
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