The Sun

1
The Sun
2
The Sun

• One of 20 billion stars in the Milky Way
• Primary energy source for Earth
• Only star suitable for surface studies

3
The Sun

• Four areas for research
• Interior sun
• Visible surface (photosphere)
• Atmosphere
• Chromosphere
• Corona

4
Diagram of the Sun
5
The Photosphere

• Radiates most of visible sunlight
• Layer of incandescent gas
• lt 500 km thick
• lt 1/100 of Earths atmospheric pressure
• Granules

6
The Photosphere contd

• Granules
• Bright markings
• About the size of Texas
• Spread laterally
• Life span of about 10 to 20 minutes
• This cycle is called convection
• Transfer of energy in uppermost part of Suns
  interior

7
The Photosphere contd

• The suns absorption spectrum reveals
• 90 hydrogen
• 10 helium
• lt1 other elements (same as found on Earth)

8
Diagram of the Sun
9
The Chromosphere
10
The Chromosphere contd

• Lies outside the photosphere
• Only a few thousand km thick
• Hot incandescent gas
• Best seen during solar eclipse
• Study of chromospheric spektrum in 1868
• New element found helium
• Helios greek word for sun
• Corona

11
Corona (well not quite)
12
Corona
13
Corona contd
14
UV Corona
15
Corona

• Corona (lat.) sun
• Only visible when photosphere is covered
• Extends up to one million km from sun
• Ionized gas
• Sufficient escape velocity
• 250 800 km/s
• Solar wind
• Protons and electrons
• Earth is shielded by magnetic field
• 6000 K to one million K

16
Solar Eclipse

• http//www.chromosphere.co.uk/gallery/astronomy/so
  lar/eclipses/denia-spain---2005/

17
Features of the Sun

• Sunspots
• Dark spots on surface
• Equator rotates faster then poles
• Prominences
• Chromospheric gas
• Solar flares
• Intense solar wind
• Causes auroras

18
Sunspots
19
Features of the Sun

• Sunspots
• Dark spots on surface
• Equator rotates faster then poles
• Prominences
• Chromospheric gas
• Solar flares
• Intense solar wind
• Causes auroras

20
Prominences
21
Promineces
22
Features of the Sun

• Sunspots
• Dark spots on surface
• Equator rotates faster then poles
• Prominences
• Chromospheric gas
• Solar flares
• Intense solar wind
• Causes auroras

23
Solar Flare
24
Features of the Sun

• Sunspots
• Dark spots on surface
• Equator rotates faster then poles
• Prominences
• Chromospheric gas
• Solar flares
• Intense solar wind
• Causes auroras

25
Aurora
26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)