![Page 1: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/1.jpg)
Shadows on the SunThe story of sunspots
Dr. Lyndsay Fletcher, University of Glasgow
![Page 2: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/2.jpg)
Image: Bill Leslie, Forres
![Page 3: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/3.jpg)
The first recorded observation
Photocredit: Michael Myers
364 BC – Chinese astronomer Gan-De records a darkening on the face of the Sun.
Sunspots recorded regularly by ~ 30 BC.
Observing through thin cloud or smoke?
Photocredit: Ed Sanders
![Page 4: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/4.jpg)
A Perfect Body?300-250 BC - The Aristotelian view of the Universe
The Earth is at the centre of a set of revolving spheres,each carrying a perfect andimmutable celestial body
The Sun is one such perfect body and should therefore be free of flaws
But Theophrastus (374-287 B.C.) claims to observe flaws on the Sun
![Page 5: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/5.jpg)
The first known drawing of sunspots?by John of Worcester, 8th December 1128
The first sunspot drawing
![Page 6: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/6.jpg)
The Copernican Revolution
1543 - the Sun at the centre of the ‘Universe’Sunspot observations have a bearing on the 16th C. cosmology,
demonstrating that heavenly bodies are not perfect and unchanging.
![Page 7: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/7.jpg)
The first telescopic observationsGalileo is usually credited with first turning a telescope to look at the Sun. This might not be correct!
Galileo Scheiner Fabricius Harriot
The four contenders are:
![Page 8: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/8.jpg)
Galileo claimed tohave been observingsunspots since theAutumn of 1610.
However, his first public demonstration was in 1611.
![Page 9: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/9.jpg)
The first known record of a telescopic sunspot observation
This was drawn by the English mathematicianThomas Harriot….
..on 8th December 1610
![Page 10: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/10.jpg)
‘..the greatest mathematician thatOxford has produced.’
Thomas Harriot
1560 -1621
![Page 11: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/11.jpg)
1613, Italy 2001, Hawai’i
![Page 12: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/12.jpg)
![Page 13: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/13.jpg)
Heinrich Schwabe
The 11-year cycle
![Page 14: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/14.jpg)
Image: NASA/ISAS/LMSAL Yohkoh
1992
1996
2001
![Page 15: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/15.jpg)
Movie: NASA Sun-Earth Connections
![Page 16: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/16.jpg)
Close-up of an active region (TRACE satellite)
![Page 17: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/17.jpg)
Iron filings around a bar magnet line up according to magnetic force field.
Coronal plasma is also tied to magnetic force field
![Page 18: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/18.jpg)
Solar magnetic fieldWhite = ‘north’ Black = ‘south’
![Page 19: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/19.jpg)
umbra
penumbra
A Simple Sunspot
![Page 20: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/20.jpg)
Images: Swedish Solar Telescope
![Page 21: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/21.jpg)
Why are sunspots dark?Because they are cooler than their surroundings, and so produce less radiation:
![Page 22: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/22.jpg)
Why are sunspots cool?
Because they are so strongly magnetised
Magnetic field ‘resists’ convection, so heat from the rest of the photosphere can’t be fed into the sunspot
![Page 23: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/23.jpg)
![Page 24: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/24.jpg)
![Page 25: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/25.jpg)
Image: NASA/ISAS/LMSAL Yohkoh
1992
1996
2001
![Page 26: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/26.jpg)
![Page 27: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/27.jpg)
A topical question – the effect of solar activity on climate
Clear historical association of periods of low sunspot number and the Earth’s climate. Is this still important?
![Page 28: Shadows on the Sun The story of sunspots Dr. Lyndsay Fletcher, University of Glasgow](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649e225503460f94b0fea0/html5/thumbnails/28.jpg)
http://solarb.msfc.nasa.gov/index.html
http://sdo.gsfc.nasa.gov/
http://trace.lmsal.com/
http://sohowww.nascom.nasa.gov/
More images and movies at: