The Sun is a dynamic object with complex internal structure and outer atmosphere. It has a core reaching temperatures over 27 million degrees Fahrenheit where nuclear fusion occurs. Energy radiates outward through the radiative zone and flows in convection currents in the convection zone before emerging in the photosphere. Above the photosphere lies the chromosphere and transition region where temperatures rise into the million degrees before reaching the super-hot corona extending far into space. The solar wind and coronal mass ejections influence space weather throughout the solar system.

1. Our Dynamic Sun
You should never look directly at
the sun.

2. The Sun is Large
• How
• Large
• is
• It?

3. http://space-facts.com/how-big-
is-the-sun-million-earths/
• 1.3 million Earths will fit in the sun.
• https://www.youtube.com/watch?v=qLB
5ma2Yz1I
• What is happening up there?

4. Interior
• Interior:
http://solarscience.msfc.nasa.gov/interior.
shtml
• 1. Core: The Sun's core
• is the central region
• where nuclear reactions
• consume hydrogen to
• form helium.
• Temp: 27,000,000 O
F

5. Here is how fusion works:
• (3) step process called proton-proton
chain. (fusion)

6. step one summary
• Proton + Proton
• H + H = deuterium + neutrino
• and a positron

7. Gamma Ray
• When a positron collides with its
• antiparticle (electron) they annihilate
• to form a gamma ray.
• These gamma rays eventually make their
way into space in the form of sunlight.
• neutrinos just come out and can eventually
• make it to earth.

8. Step Two summary:
deuterium + proton = Helium-3 nucleus
and a gamma ray.

9. Step Three Summary
Two Helium-3
collide to form
a Helium 4
nucleus and
2 extra protons

10. Radiative Zone
Characterized by the fact
that the energy from the
core is carried by photons
through the radiative zone.
Because of the density, it
takes a photon about a
million years to finally reach
the interface layer.

11. Radiative Zone
• Temperature falls to about 2,000,000
0
C progressively through this zone.

12. Tachocline (Interface Layer)
• This is an area that lies between the
Radiative zone and the Convective Zone.
• This is where the suns magnetic field is
generated.
• Thin layer with border behaviors to match
each border.
• This change in fluid flow velocities gives
its alternative name: Tachocline Layer.

13. Convection Zone
• Outer most layer. This is the begining
• of the visible surface.
• Material is more opaque here because
• heavier ions hold onto some of their
• electrons.
• Radiation has a harder time getting
through.

14. Convection Zone
• So heat is trapped and the fluids start to
boil. Then material starts to move
• higher and since this material is warmer
• it will rise higher until it reaches the
surface.
At the visible surface the temp is about
• 5426 0
C. Density is .0000002 g/cm3
.
• Convective motion is visible at the surface.

15. Interior Summary

16. Photosphere
• Photosphere: The
• visible surface of the
• sun that we are most
• familiar with.
• Has sunspots, prominences,
• and granules.
• http://solarscience.msfc.nasa.gov/surface.shtml

17. Chromosphere
• http://solarscience.msfc.nasa.gov/chro
mos.shtml
An irregular layer above the photosphere
where the temperature rises from 6000°C
to about 20,000°C.
At these temps Hydrogen emits red light
which is seen as prominences during a
solar eclipse.

18. Transition Region
• The Transition Region:
http://solarscience.msfc.nasa.gov/t_reg
ion.shtml
The transition region is a thin and
very irregular layer of the Sun's
atmosphere that separates the
hot corona from the much
cooler chromosphere.

19. The Transition Region
Instead of hydrogen, the light emitted by
the transition region is dominated by such
ions as C IV, O IV, and Si IV (carbon,
oxygen, and silicon each with three
electrons stripped off)

20. Corona
• 1. Sun’s Outer Atmosphere
• Features: Streamers, Plumes, Loops
White Light
Corona – visible
during eclipse.

21. Corona
Emission line Corona: Hydrogen and Helium
are super heated to temps > 1,800,000°F. They are
stripped of their electrons. Other elements like
N, C, and O are stripped down to nuclei. These ionized
elements produce odd emission lines in a spectrum.

22. Corona
X Ray Corona: The corona shines brightly in x-
rays because of its high temperature. On the other
hand, the "cool" solar photosphere emits very few x-
rays.

23. Space Weather
• The solar wind streams off of the Sun in all
directions at speeds of about 400 km/s (about
• 1 million miles per hour).
• The source of the
• solar wind is the
• Sun's hot corona.
• The temperature of
• the corona is so high
• that the Sun's gravity
• cannot hold on to it.

24. Coronal Mass Ejections
• CMEs: http://www.space.com/12581-
stunning-photos-solar-storms-flares-sun-
weather.html
• Coronal Mass Ejections: are huge bubbles
of gas threaded with magnetic field lines
that are ejected from the Sun over the
course of several hours
• These can cause interference with
• electronics.

25. More Space Weather
• Solar Wind:
http://solarscience.msfc.nasa.gov/Solar
Wind.shtml
• Heliosphere:
http://solarscience.msfc.nasa.gov/Helio
sphere.shtml

26. Heliosphere
• The heliosphere is a bubble in space
produced by the solar wind.

27. Some Interesting features
• http://www.nasa.gov/mission_pages/sdo/n
ews/first-light.html
• The above is for SD Observatory facts
from NASA and a solar prominence video.
• Solar Flare:
• http://www.nasa.gov/mission_pages/sunear
th/multimedia/Solar-
Events.html#.VMp13i4sCDk

28. Montage

29. More Montage

30. And even more Montage